Add local cargo registry type

- serve sparse index and config.json for local cargo repos from a cargo_index table
- add Web API publish, yank and unyank under the local repo api root
- drop index lines when the crate file is deleted

.woodpecker/docker.yaml

@@ -4,31 +4,45 @@ when:
 
 steps:
   - name: docker-api
-    image: woodpeckerci/plugin-docker-buildx
+    image: artifactapi.k8s.syd1.au.unkin.net/docker-internal/plugin-docker-buildx:latest
     settings:
-      registry: git.unkin.net
-      repo: git.unkin.net/unkin/artifactapi
+      registry: artifactapi.k8s.syd1.au.unkin.net
+      repo: artifactapi.k8s.syd1.au.unkin.net/docker-internal/artifactapi
       build_args:
         VERSION: ${CI_COMMIT_TAG}
-      username: droneci
-      password:
-        from_secret: DRONECI_PASSWORD
       tags:
         - ${CI_COMMIT_TAG}
         - latest
+    backend_options:
+      kubernetes:
+        serviceAccountName: default
+        resources:
+          requests:
+            memory: 1Gi
+            cpu: 1
+          limits:
+            memory: 4Gi
+            cpu: 2
 
   - name: docker-web
-    image: woodpeckerci/plugin-docker-buildx
+    image: artifactapi.k8s.syd1.au.unkin.net/docker-internal/plugin-docker-buildx:latest
     settings:
-      registry: git.unkin.net
-      repo: git.unkin.net/unkin/artifactapi-ui
+      registry: artifactapi.k8s.syd1.au.unkin.net
+      repo: artifactapi.k8s.syd1.au.unkin.net/docker-internal/artifactapi-ui
       dockerfile: ui/Dockerfile.ui
       context: ui
       build_args:
         BASE_PATH: /ui
-      username: droneci
-      password:
-        from_secret: DRONECI_PASSWORD
       tags:
         - ${CI_COMMIT_TAG}
         - latest
+    backend_options:
+      kubernetes:
+        serviceAccountName: default
+        resources:
+          requests:
+            memory: 1Gi
+            cpu: 1
+          limits:
+            memory: 4Gi
+            cpu: 2

README.md

@@ -279,6 +279,20 @@ content-addressable store (deduplicated by digest, reaped by GC once
 unreferenced); tags are mutable references and re-pushing a tag moves it. Blob
 uploads support both the monolithic and chunked (`POST`/`PATCH`/`PUT`) flows.
 
+### Local cargo registry
+
+A local `cargo` repo is a private crate registry: it serves the sparse index and
+the Web API publish, yank and unyank endpoints, so `cargo publish` works against
+it directly.
+
+```toml
+[registries.<repo>]
+index = "sparse+https://artifactapi.k8s.syd1.au.unkin.net/api/v1/local/<repo>/"
+```
+
+cargo requires a token for publish/yank (`CARGO_REGISTRIES_<REPO>_TOKEN`); like
+other local repos, artifactapi does not check it.
+
 ## Access Control
 
 | Field | Default | Behaviour |
@@ -371,6 +385,8 @@ additive and idempotent for the same reason; a test enforces it.
 | `GITHUB_APP_INSTALLATION_ID` | | GitHub App installation id |
 | `GITHUB_APP_PRIVATE_KEY` | | GitHub App private key, inline PEM |
 | `GITHUB_APP_PRIVATE_KEY_PATH` | | GitHub App private key, file path (alternative to inline PEM) |
+| `ARTIFACTAPI_OIDC_ISSUER` | | OIDC issuer URL (e.g. Vault `https://vault.service.consul:8200/v1/identity/oidc`). When set, `POST /api/v2/remotes`, `POST /api/v2/virtuals` and `PUT`/`DELETE` on `/api/v2/{remotes,virtuals}/{name}` require `Authorization: Bearer <jwt>` verified against the issuer's JWKS. Uploads, object/file deletes, probe, reads and `/v2` stay open. Unset = no auth |
+| `ARTIFACTAPI_OIDC_AUDIENCE` | | Comma-separated allowed `aud` values (e.g. the Vault OIDC role's client_id). Required when `ARTIFACTAPI_OIDC_ISSUER` is set |
 
 ## Development
 

e2e-docker/README.md

@@ -27,7 +27,8 @@ already-running stack.
   mock upstream: first fetch `X-Artifact-Source: remote`, second `cache`, bytes
   verified against the origin fixture.
 - **Local uploads** — generic (upload/download), pypi (wheel + generated `simple/`
-  index), rpm (real package + **automatic repodata** generation).
+  index), rpm (real package + **automatic repodata** generation), cargo (publish,
+  sparse index, download, yank).
 - **Virtual repositories** — pypi simple-index merge and helm `index.yaml` merge
   across two members.
 - **Mirrorlist** — an rpm remote with a `mirrorlist` of extra upstream mirrors

e2e-docker/cargo_local_test.go

@@ -0,0 +1,56 @@
+//go:build dockere2e
+
+package e2edocker
+
+import (
+	"bytes"
+	"encoding/binary"
+	"net/http"
+	"strings"
+	"testing"
+)
+
+// TestLocalCargoRegistry publishes through the cargo Web API, then reads the
+// sparse index, downloads the crate and yanks it.
+func TestLocalCargoRegistry(t *testing.T) {
+	createRepo(t, `{"name":"local-cargo","package_type":"cargo","repo_type":"local"}`)
+	defer deleteRepo(t, "local-cargo")
+	base := api("/api/v1/local/local-cargo")
+
+	meta := `{"name":"e2e-crate","vers":"0.1.0","deps":[],"features":{}}`
+	crate := []byte("e2e crate bytes")
+	var body []byte
+	body = binary.LittleEndian.AppendUint32(body, uint32(len(meta)))
+	body = append(body, meta...)
+	body = binary.LittleEndian.AppendUint32(body, uint32(len(crate)))
+	body = append(body, crate...)
+
+	if resp, b := doRequest(t, http.MethodPut, base+"/api/v1/crates/new", body, "application/octet-stream"); resp.StatusCode != http.StatusOK {
+		t.Fatalf("publish: status %d: %s", resp.StatusCode, b)
+	}
+	if resp, _ := doRequest(t, http.MethodPut, base+"/api/v1/crates/new", body, "application/octet-stream"); resp.StatusCode != http.StatusConflict {
+		t.Fatalf("republish: status %d, want 409", resp.StatusCode)
+	}
+
+	resp, b := doRequest(t, http.MethodGet, base+"/config.json", nil, "")
+	if resp.StatusCode != http.StatusOK || !strings.Contains(string(b), `"api":"`) {
+		t.Fatalf("config.json: status %d: %s", resp.StatusCode, b)
+	}
+
+	resp, b = doRequest(t, http.MethodGet, base+"/e2/e-/e2e-crate", nil, "")
+	if resp.StatusCode != http.StatusOK || !strings.Contains(string(b), `"cksum":"`) || !strings.Contains(string(b), `"yanked":false`) {
+		t.Fatalf("index: status %d: %s", resp.StatusCode, b)
+	}
+
+	resp, b = doRequest(t, http.MethodGet, base+"/crates/e2e-crate/e2e-crate-0.1.0.crate", nil, "")
+	if resp.StatusCode != http.StatusOK || !bytes.Equal(b, crate) {
+		t.Fatalf("download: status %d", resp.StatusCode)
+	}
+
+	if resp, b := doRequest(t, http.MethodDelete, base+"/api/v1/crates/e2e-crate/0.1.0/yank", nil, ""); resp.StatusCode != http.StatusOK {
+		t.Fatalf("yank: status %d: %s", resp.StatusCode, b)
+	}
+	if _, b := doRequest(t, http.MethodGet, base+"/e2/e-/e2e-crate", nil, ""); !strings.Contains(string(b), `"yanked":true`) {
+		t.Fatalf("index after yank: %s", b)
+	}
+}

go.mod

@@ -7,7 +7,9 @@ require (
 	github.com/cavaliergopher/rpm v1.3.0
 	github.com/charmbracelet/bubbletea v1.3.10
 	github.com/charmbracelet/lipgloss v1.1.0
+	github.com/coreos/go-oidc/v3 v3.21.0
 	github.com/go-chi/chi/v5 v5.3.0
+	github.com/go-jose/go-jose/v4 v4.1.4
 	github.com/google/uuid v1.6.0
 	github.com/jackc/pgx/v5 v5.10.0
 	github.com/klauspost/compress v1.19.2
@@ -102,6 +104,7 @@ require (
 	go.uber.org/atomic v1.11.0 // indirect
 	go.yaml.in/yaml/v3 v3.0.4 // indirect
 	golang.org/x/net v0.56.0 // indirect
+	golang.org/x/oauth2 v0.36.0 // indirect
 	golang.org/x/sys v0.47.0 // indirect
 	golang.org/x/text v0.40.0 // indirect
 	gopkg.in/ini.v1 v1.67.2 // indirect

go.sum

@@ -44,6 +44,8 @@ github.com/containerd/log v0.1.0 h1:TCJt7ioM2cr/tfR8GPbGf9/VRAX8D2B4PjzCpfX540I=
 github.com/containerd/log v0.1.0/go.mod h1:VRRf09a7mHDIRezVKTRCrOq78v577GXq3bSa3EhrzVo=
 github.com/containerd/platforms v0.2.1 h1:zvwtM3rz2YHPQsF2CHYM8+KtB5dvhISiXh5ZpSBQv6A=
 github.com/containerd/platforms v0.2.1/go.mod h1:XHCb+2/hzowdiut9rkudds9bE5yJ7npe7dG/wG+uFPw=
+github.com/coreos/go-oidc/v3 v3.21.0 h1:wZo4Q9Pum8dYEj0eMUPrqR+kvuGkeUplbLpNCkBqoWM=
+github.com/coreos/go-oidc/v3 v3.21.0/go.mod h1:DYCf24+ncYi+XkIH97GY1+dqoRlbaSI26KVTCI9SrY4=
 github.com/cpuguy83/dockercfg v0.3.2 h1:DlJTyZGBDlXqUZ2Dk2Q3xHs/FtnooJJVaad2S9GKorA=
 github.com/cpuguy83/dockercfg v0.3.2/go.mod h1:sugsbF4//dDlL/i+S+rtpIWp+5h0BHJHfjj5/jFyUJc=
 github.com/creack/pty v1.1.24 h1:bJrF4RRfyJnbTJqzRLHzcGaZK1NeM5kTC9jGgovnR1s=
@@ -67,6 +69,8 @@ github.com/felixge/httpsnoop v1.1.0 h1:3YtUj32ZZkqZtt3sZZsClsymw/QDuVfpNhoA31zeO
 github.com/felixge/httpsnoop v1.1.0/go.mod h1:Zqxgdd+1Rkcz8euOqdr7lqgCRJztwr5hp9vDSi5UZCE=
 github.com/go-chi/chi/v5 v5.3.0 h1:halUjDxhshgXHMrao5bB8eNBXo/rnzwr8m5m36glehM=
 github.com/go-chi/chi/v5 v5.3.0/go.mod h1:R+tYY2hNuVUUjxoPtqUdgBqevM9s9njzkTLutVsOCto=
+github.com/go-jose/go-jose/v4 v4.1.4 h1:moDMcTHmvE6Groj34emNPLs/qtYXRVcd6S7NHbHz3kA=
+github.com/go-jose/go-jose/v4 v4.1.4/go.mod h1:x4oUasVrzR7071A4TnHLGSPpNOm2a21K9Kf04k1rs08=
 github.com/go-logr/logr v1.2.2/go.mod h1:jdQByPbusPIv2/zmleS9BjJVeZ6kBagPoEUsqbVz/1A=
 github.com/go-logr/logr v1.4.3 h1:CjnDlHq8ikf6E492q6eKboGOC0T8CDaOvkHCIg8idEI=
 github.com/go-logr/logr v1.4.3/go.mod h1:9T104GzyrTigFIr8wt5mBrctHMim0Nb2HLGrmQ40KvY=
@@ -225,6 +229,8 @@ golang.org/x/exp v0.0.0-20231006140011-7918f672742d h1:jtJma62tbqLibJ5sFQz8bKtEM
 golang.org/x/exp v0.0.0-20231006140011-7918f672742d/go.mod h1:ldy0pHrwJyGW56pPQzzkH36rKxoZW1tw7ZJpeKx+hdo=
 golang.org/x/net v0.56.0 h1:Rw8j/hFzGvJUZwNBXnAtf5sVDVt+65SK2C7IxCxZt5o=
 golang.org/x/net v0.56.0/go.mod h1:D3Ku6r+V6JROoZK144D2XfMHFcMq/0zSfLelVTCFKec=
+golang.org/x/oauth2 v0.36.0 h1:peZ/1z27fi9hUOFCAZaHyrpWG5lwe0RJEEEeH0ThlIs=
+golang.org/x/oauth2 v0.36.0/go.mod h1:YDBUJMTkDnJS+A4BP4eZBjCqtokkg1hODuPjwiGPO7Q=
 golang.org/x/sync v0.22.0 h1:SZjpbeLmrCk4xhRSZFNZW5gFUeCeFgjekvI/+gfScek=
 golang.org/x/sync v0.22.0/go.mod h1:9xrNwdLfx4jkKbNva9FpL6vEN7evnE43NNNJQ2LF3+0=
 golang.org/x/sys v0.0.0-20190916202348-b4ddaad3f8a3/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=

internal/api/v1/cargo.go

@@ -0,0 +1,148 @@
+package v1
+
+import (
+	"bytes"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"log/slog"
+	"net/http"
+
+	"github.com/go-chi/chi/v5"
+
+	"git.unkin.net/unkin/artifactapi/internal/database"
+	"git.unkin.net/unkin/artifactapi/internal/provider"
+	"git.unkin.net/unkin/artifactapi/internal/provider/cargo"
+	"git.unkin.net/unkin/artifactapi/pkg/models"
+)
+
+// This file implements the cargo registry Web API (publish, yank, unyank) for
+// local cargo repositories. config.json points api at /api/v1/local/<repo>, so
+// cargo appends its own /api/v1/crates/... below that.
+
+const maxCratePublish = 64 << 20
+
+func (h *ProxyHandler) localCargoRemote(r *http.Request) (*models.Remote, bool) {
+	remote, err := h.db.GetRemote(r.Context(), chi.URLParam(r, "localName"))
+	if err != nil {
+		return nil, false
+	}
+	return remote, remote.RepoType == models.RepoTypeLocal && remote.PackageType == models.PackageCargo
+}
+
+func cargoError(w http.ResponseWriter, status int, format string, args ...any) {
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(status)
+	_ = json.NewEncoder(w).Encode(map[string]any{
+		"errors": []map[string]string{{"detail": fmt.Sprintf(format, args...)}},
+	})
+}
+
+func cargoOK(w http.ResponseWriter, v any) {
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(http.StatusOK)
+	_ = json.NewEncoder(w).Encode(v)
+}
+
+func (h *ProxyHandler) cargoPublish(w http.ResponseWriter, r *http.Request) {
+	remote, ok := h.localCargoRemote(r)
+	if !ok {
+		cargoError(w, http.StatusNotFound, "no local cargo registry %q", chi.URLParam(r, "localName"))
+		return
+	}
+	ctx := r.Context()
+
+	body, err := io.ReadAll(io.LimitReader(r.Body, maxCratePublish+1))
+	if err != nil {
+		cargoError(w, http.StatusBadRequest, "read body: %v", err)
+		return
+	}
+	if len(body) > maxCratePublish {
+		cargoError(w, http.StatusRequestEntityTooLarge, "publish body exceeds %d bytes", maxCratePublish)
+		return
+	}
+	meta, crate, err := cargo.ParsePublish(body)
+	if err != nil {
+		cargoError(w, http.StatusBadRequest, "%v", err)
+		return
+	}
+	line, err := cargo.NewIndexLine(meta, crate)
+	if err != nil {
+		cargoError(w, http.StatusBadRequest, "%v", err)
+		return
+	}
+
+	existing, err := h.db.ListCargoIndexEntries(ctx, remote.Name, meta.Name)
+	if err != nil {
+		cargoError(w, http.StatusInternalServerError, "%v", err)
+		return
+	}
+	for _, e := range existing {
+		if e.Name != meta.Name {
+			cargoError(w, http.StatusBadRequest, "crate %q already exists as %q", meta.Name, e.Name)
+			return
+		}
+		if e.Version == meta.Vers {
+			cargoError(w, http.StatusConflict, "crate version `%s@%s` already exists", meta.Name, meta.Vers)
+			return
+		}
+	}
+
+	lineJSON, err := json.Marshal(line)
+	if err != nil {
+		cargoError(w, http.StatusInternalServerError, "%v", err)
+		return
+	}
+
+	path := cargo.CratePath(meta.Name, meta.Vers)
+	result, err := h.cas.Store(ctx, bytes.NewReader(crate), "application/gzip")
+	if err != nil {
+		cargoError(w, http.StatusInternalServerError, "store failed: %v", err)
+		return
+	}
+	if err := h.db.UpsertBlob(ctx, result.ContentHash, result.S3Key, result.SizeBytes, "application/gzip"); err != nil {
+		cargoError(w, http.StatusInternalServerError, "record blob: %v", err)
+		return
+	}
+	if err := h.db.CreateLocalFile(ctx, remote.Name, path, result.ContentHash); err != nil {
+		if errors.Is(err, database.ErrAlreadyExists) {
+			cargoError(w, http.StatusConflict, "crate version `%s@%s` already exists", meta.Name, meta.Vers)
+			return
+		}
+		cargoError(w, http.StatusInternalServerError, "record file: %v", err)
+		return
+	}
+	entry := &provider.CargoIndexEntry{RepoName: remote.Name, FilePath: path, Name: meta.Name, Version: meta.Vers, Line: string(lineJSON)}
+	if err := h.db.InsertCargoIndexEntry(ctx, entry); err != nil {
+		// Drop the file so a retry is not rejected as a duplicate.
+		_ = h.db.DeleteLocalFile(ctx, remote.Name, path)
+		cargoError(w, http.StatusInternalServerError, "record index: %v", err)
+		return
+	}
+
+	slog.Info("cargo: published", "repo", remote.Name, "crate", meta.Name, "version", meta.Vers)
+	cargoOK(w, map[string]any{"warnings": map[string][]string{"invalid_categories": {}, "invalid_badges": {}, "other": {}}})
+}
+
+func (h *ProxyHandler) cargoYank(yanked bool) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		remote, ok := h.localCargoRemote(r)
+		if !ok {
+			cargoError(w, http.StatusNotFound, "no local cargo registry %q", chi.URLParam(r, "localName"))
+			return
+		}
+		name, version := chi.URLParam(r, "crate"), chi.URLParam(r, "version")
+		found, err := h.db.SetCargoYanked(r.Context(), remote.Name, name, version, yanked)
+		if err != nil {
+			cargoError(w, http.StatusInternalServerError, "%v", err)
+			return
+		}
+		if !found {
+			cargoError(w, http.StatusNotFound, "crate version `%s@%s` not found", name, version)
+			return
+		}
+		slog.Info("cargo: yank updated", "repo", remote.Name, "crate", name, "version", version, "yanked", yanked)
+		cargoOK(w, map[string]bool{"ok": true})
+	}
+}

internal/api/v1/proxy.go

@@ -41,6 +41,9 @@ func (h *ProxyHandler) Routes() chi.Router {
 	r := chi.NewRouter()
 	r.Get("/remote/{remoteName}/*", h.handleProxy)
 	r.Get("/local/{localName}/*", h.handleLocal)
+	r.Put("/local/{localName}/api/v1/crates/new", h.cargoPublish)
+	r.Delete("/local/{localName}/api/v1/crates/{crate}/{version}/yank", h.cargoYank(true))
+	r.Put("/local/{localName}/api/v1/crates/{crate}/{version}/unyank", h.cargoYank(false))
 	r.Get("/virtual/{virtualName}/*", h.handleVirtual)
 	return r
 }

internal/auth/oidc.go

@@ -0,0 +1,158 @@
+package auth
+
+import (
+	"context"
+	"errors"
+	"log/slog"
+	"net/http"
+	"slices"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/coreos/go-oidc/v3/oidc"
+)
+
+// BearerOIDC verifies `Authorization: Bearer <jwt>` against an OIDC issuer's
+// JWKS. Discovery is lazy so startup never depends on the issuer being
+// reachable; a failed discovery is not retried until the backoff elapses.
+type BearerOIDC struct {
+	issuer    string
+	audiences []string
+	timeout   time.Duration
+	backoff   time.Duration
+	discover  func(context.Context, string) (*oidc.Provider, error)
+
+	mu       sync.Mutex
+	verifier *oidc.IDTokenVerifier
+	inflight chan struct{}
+	failedAt time.Time
+}
+
+var errIssuerUnavailable = errors.New("oidc issuer unavailable")
+
+// NewBearerOIDC returns nil when issuer is empty, meaning auth is disabled.
+func NewBearerOIDC(issuer string, audiences []string) *BearerOIDC {
+	if issuer == "" {
+		return nil
+	}
+	return &BearerOIDC{issuer: issuer, audiences: audiences, timeout: 10 * time.Second, backoff: 15 * time.Second, discover: oidc.NewProvider}
+}
+
+// getVerifier runs at most one discovery at a time without holding the lock
+// across network I/O; concurrent callers wait for it, and only callers within
+// the post-failure backoff fail fast.
+func (b *BearerOIDC) getVerifier(ctx context.Context) (*oidc.IDTokenVerifier, error) {
+	b.mu.Lock()
+	if v := b.verifier; v != nil {
+		b.mu.Unlock()
+		return v, nil
+	}
+	if done := b.inflight; done != nil {
+		b.mu.Unlock()
+		select {
+		case <-done:
+		case <-ctx.Done():
+			return nil, ctx.Err()
+		}
+		b.mu.Lock()
+		defer b.mu.Unlock()
+		if b.verifier == nil {
+			return nil, errIssuerUnavailable
+		}
+		return b.verifier, nil
+	}
+	if time.Since(b.failedAt) < b.backoff {
+		b.mu.Unlock()
+		return nil, errIssuerUnavailable
+	}
+	done := make(chan struct{})
+	b.inflight = done
+	b.mu.Unlock()
+
+	v, err := b.discoverOnce(done)
+	if err != nil {
+		slog.Error("oidc discovery failed", "issuer", b.issuer, "error", err)
+		return nil, err
+	}
+	return v, nil
+}
+
+// discoverOnce releases inflight and waiters on every exit, a panic included,
+// recording failedAt unless discovery succeeded.
+func (b *BearerOIDC) discoverOnce(done chan struct{}) (v *oidc.IDTokenVerifier, err error) {
+	defer func() {
+		b.mu.Lock()
+		b.inflight = nil
+		if v == nil {
+			b.failedAt = time.Now()
+		}
+		b.verifier = v
+		b.mu.Unlock()
+		close(done)
+	}()
+	// The provider keeps this context and client for JWKS refreshes, so the
+	// deadline lives on the client rather than the context.
+	client := &http.Client{Timeout: b.timeout}
+	p, err := b.discover(oidc.ClientContext(context.Background(), client), b.issuer)
+	if err != nil {
+		return nil, err
+	}
+	return p.Verifier(&oidc.Config{SkipClientIDCheck: true}), nil
+}
+
+// Require gates every request through next on a valid token. A nil receiver
+// passes everything through.
+func (b *BearerOIDC) Require(next http.Handler) http.Handler {
+	if b == nil {
+		return next
+	}
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		scheme, raw, _ := strings.Cut(strings.TrimSpace(r.Header.Get("Authorization")), " ")
+		raw = strings.TrimSpace(raw)
+		if !strings.EqualFold(scheme, "Bearer") || raw == "" {
+			unauthorized(w, "missing bearer token")
+			return
+		}
+		v, err := b.getVerifier(r.Context())
+		if err != nil {
+			w.Header().Set("Content-Type", "application/json")
+			w.WriteHeader(http.StatusServiceUnavailable)
+			_, _ = w.Write([]byte(`{"error":"token issuer unavailable"}`))
+			return
+		}
+		tok, err := v.Verify(r.Context(), raw)
+		if err != nil {
+			slog.Info("bearer token rejected", "error", err)
+			unauthorized(w, "invalid token")
+			return
+		}
+		if len(b.audiences) > 0 && !slices.ContainsFunc(tok.Audience, func(a string) bool { return slices.Contains(b.audiences, a) }) {
+			slog.Info("bearer token rejected", "error", "audience not allowed", "aud", tok.Audience)
+			unauthorized(w, "invalid token")
+			return
+		}
+		slog.Info("bearer token accepted", "sub", tok.Subject, "method", r.Method, "path", r.URL.Path)
+		next.ServeHTTP(w, r)
+	})
+}
+
+// RequireWrites gates only mutating methods.
+func (b *BearerOIDC) RequireWrites(next http.Handler) http.Handler {
+	gated := b.Require(next)
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		switch r.Method {
+		case http.MethodGet, http.MethodHead, http.MethodOptions:
+			next.ServeHTTP(w, r)
+		default:
+			gated.ServeHTTP(w, r)
+		}
+	})
+}
+
+func unauthorized(w http.ResponseWriter, msg string) {
+	w.Header().Set("Content-Type", "application/json")
+	w.Header().Set("WWW-Authenticate", "Bearer")
+	w.WriteHeader(http.StatusUnauthorized)
+	_, _ = w.Write([]byte(`{"error":"` + msg + `"}`))
+}

internal/auth/oidc_test.go

@@ -0,0 +1,255 @@
+package auth
+
+import (
+	"context"
+	"crypto/rand"
+	"crypto/rsa"
+	"encoding/base64"
+	"net/http"
+	"net/http/httptest"
+	"strconv"
+	"sync"
+	"sync/atomic"
+	"testing"
+	"time"
+
+	"github.com/coreos/go-oidc/v3/oidc"
+	"github.com/go-jose/go-jose/v4"
+	"github.com/go-jose/go-jose/v4/jwt"
+
+	"git.unkin.net/unkin/artifactapi/internal/testsupport"
+)
+
+func serve(h http.Handler, method, token string) int {
+	if token == "" {
+		return serveAuth(h, method, "")
+	}
+	return serveAuth(h, method, "Bearer "+token)
+}
+
+func serveAuth(h http.Handler, method, authz string) int {
+	r := httptest.NewRequest(method, "/x", nil)
+	if authz != "" {
+		r.Header.Set("Authorization", authz)
+	}
+	w := httptest.NewRecorder()
+	h.ServeHTTP(w, r)
+	return w.Code
+}
+
+func claims(iss string) jwt.Claims {
+	now := time.Now()
+	return jwt.Claims{
+		Issuer:   iss,
+		Subject:  "ci",
+		Audience: jwt.Audience{"artifactapi"},
+		IssuedAt: jwt.NewNumericDate(now.Add(-time.Minute)),
+		Expiry:   jwt.NewNumericDate(now.Add(time.Hour)),
+	}
+}
+
+func hs256Token(t *testing.T, c jwt.Claims) string {
+	sig, err := jose.NewSigner(jose.SigningKey{Algorithm: jose.HS256, Key: []byte("0123456789abcdef0123456789abcdef")},
+		(&jose.SignerOptions{}).WithType("JWT").WithHeader("kid", "k1"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	tok, err := jwt.Signed(sig).Claims(c).Serialize()
+	if err != nil {
+		t.Fatal(err)
+	}
+	return tok
+}
+
+func noneToken(iss string) string {
+	enc := base64.RawURLEncoding.EncodeToString
+	return enc([]byte(`{"alg":"none","typ":"JWT","kid":"k1"}`)) + "." +
+		enc([]byte(`{"iss":"`+iss+`","sub":"ci","aud":"artifactapi","exp":`+strconv.FormatInt(time.Now().Add(time.Hour).Unix(), 10)+`}`)) + "."
+}
+
+var ok = http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { w.WriteHeader(http.StatusNoContent) })
+
+func TestBearerOIDC(t *testing.T) {
+	iss := testsupport.NewOIDCIssuer()
+	defer iss.Close()
+	h := NewBearerOIDC(iss.URL, []string{"other", "artifactapi"}).Require(ok)
+
+	otherKey, _ := rsa.GenerateKey(rand.Reader, 2048)
+	cases := []struct {
+		name  string
+		token string
+		want  int
+	}{
+		{"valid", iss.Token(nil, "artifactapi", "ci", time.Hour), http.StatusNoContent},
+		{"missing", "", http.StatusUnauthorized},
+		{"garbage", "not.a.jwt", http.StatusUnauthorized},
+		{"bad signature", iss.Token(otherKey, "artifactapi", "ci", time.Hour), http.StatusUnauthorized},
+		{"wrong aud", iss.Token(nil, "nope", "ci", time.Hour), http.StatusUnauthorized},
+		{"expired", iss.Token(nil, "artifactapi", "ci", -time.Hour), http.StatusUnauthorized},
+		{"wrong iss", iss.Sign(nil, claims("https://evil.example")), http.StatusUnauthorized},
+		{"hs256", hs256Token(t, claims(iss.URL)), http.StatusUnauthorized},
+		{"alg none", noneToken(iss.URL), http.StatusUnauthorized},
+	}
+	for _, c := range cases {
+		if got := serve(h, http.MethodPost, c.token); got != c.want {
+			t.Errorf("%s: status %d, want %d", c.name, got, c.want)
+		}
+	}
+
+	valid := iss.Token(nil, "artifactapi", "ci", time.Hour)
+	headers := []struct {
+		name  string
+		authz string
+		want  int
+	}{
+		{"lowercase scheme", "bearer " + valid, http.StatusNoContent},
+		{"extra whitespace", "  Bearer   " + valid + " ", http.StatusNoContent},
+		{"empty value", "Bearer ", http.StatusUnauthorized},
+		{"scheme only", "Bearer", http.StatusUnauthorized},
+		{"basic scheme", "Basic " + valid, http.StatusUnauthorized},
+	}
+	for _, c := range headers {
+		if got := serveAuth(h, http.MethodPost, c.authz); got != c.want {
+			t.Errorf("%s: status %d, want %d", c.name, got, c.want)
+		}
+	}
+}
+
+func TestBearerOIDCHangingIssuerBacksOff(t *testing.T) {
+	var hits atomic.Int32
+	release := make(chan struct{})
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		hits.Add(1)
+		select {
+		case <-r.Context().Done():
+		case <-release:
+		}
+	}))
+	defer srv.Close()
+	defer close(release)
+
+	b := NewBearerOIDC(srv.URL, nil)
+	b.timeout = 100 * time.Millisecond
+	b.backoff = time.Hour
+	h := b.Require(ok)
+
+	start := time.Now()
+	if got := serve(h, http.MethodPost, "x.y.z"); got != http.StatusServiceUnavailable {
+		t.Fatalf("hanging issuer: status %d, want 503", got)
+	}
+	if d := time.Since(start); d > 2*time.Second {
+		t.Fatalf("hanging issuer: took %s, timeout not applied", d)
+	}
+	if got := serve(h, http.MethodPost, "x.y.z"); got != http.StatusServiceUnavailable {
+		t.Fatalf("during backoff: status %d, want 503", got)
+	}
+	if n := hits.Load(); n != 1 {
+		t.Fatalf("issuer hit %d times, want 1", n)
+	}
+}
+
+func TestBearerOIDCPanickingDiscoveryBacksOff(t *testing.T) {
+	b := NewBearerOIDC("http://issuer.invalid", nil)
+	b.backoff = time.Hour
+	b.discover = func(context.Context, string) (*oidc.Provider, error) { panic("boom") }
+	h := b.Require(ok)
+
+	func() {
+		defer func() { _ = recover() }()
+		serve(h, http.MethodPost, "x.y.z")
+	}()
+
+	got := make(chan int, 1)
+	go func() { got <- serve(h, http.MethodPost, "x.y.z") }()
+	select {
+	case code := <-got:
+		if code != http.StatusServiceUnavailable {
+			t.Fatalf("after panic: status %d, want 503", code)
+		}
+	case <-time.After(2 * time.Second):
+		t.Fatal("after panic: request hung on stale inflight discovery")
+	}
+}
+
+func TestBearerOIDCConcurrentFirstRequestsWaitForDiscovery(t *testing.T) {
+	iss := testsupport.NewOIDCIssuer()
+	defer iss.Close()
+	var hits atomic.Int32
+	inner := iss.Config.Handler
+	iss.Config.Handler = http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.URL.Path == "/.well-known/openid-configuration" {
+			hits.Add(1)
+			time.Sleep(200 * time.Millisecond)
+		}
+		inner.ServeHTTP(w, r)
+	})
+
+	h := NewBearerOIDC(iss.URL, nil).Require(ok)
+	tok := iss.Token(nil, "artifactapi", "ci", time.Hour)
+	var wg sync.WaitGroup
+	codes := make([]int, 20)
+	for i := range codes {
+		wg.Add(1)
+		go func() {
+			defer wg.Done()
+			codes[i] = serve(h, http.MethodPost, tok)
+		}()
+	}
+	wg.Wait()
+	for i, c := range codes {
+		if c != http.StatusNoContent {
+			t.Errorf("request %d: status %d, want 204", i, c)
+		}
+	}
+	if n := hits.Load(); n != 1 {
+		t.Fatalf("discovery hit %d times, want 1", n)
+	}
+}
+
+func TestBearerOIDCRetriesAfterBackoff(t *testing.T) {
+	iss := testsupport.NewOIDCIssuer()
+	defer iss.Close()
+	b := NewBearerOIDC(iss.URL, nil)
+	b.failedAt = time.Now()
+	b.backoff = 50 * time.Millisecond
+	tok := iss.Token(nil, "artifactapi", "ci", time.Hour)
+	if got := serve(b.Require(ok), http.MethodPost, tok); got != http.StatusServiceUnavailable {
+		t.Fatalf("within backoff: status %d, want 503", got)
+	}
+	time.Sleep(60 * time.Millisecond)
+	if got := serve(b.Require(ok), http.MethodPost, tok); got != http.StatusNoContent {
+		t.Fatalf("after backoff: status %d, want 204", got)
+	}
+}
+
+func TestBearerOIDCIssuerDown(t *testing.T) {
+	iss := testsupport.NewOIDCIssuer()
+	b := NewBearerOIDC(iss.URL, []string{"artifactapi"})
+	tok := iss.Token(nil, "artifactapi", "ci", time.Hour)
+	iss.Close()
+	if got := serve(b.Require(ok), http.MethodPost, tok); got != http.StatusServiceUnavailable {
+		t.Errorf("issuer down: status %d, want 503", got)
+	}
+}
+
+func TestBearerOIDCDisabled(t *testing.T) {
+	if got := serve(NewBearerOIDC("", nil).RequireWrites(ok), http.MethodDelete, ""); got != http.StatusNoContent {
+		t.Errorf("disabled: status %d, want 204", got)
+	}
+}
+
+func TestRequireWritesLeavesReadsOpen(t *testing.T) {
+	iss := testsupport.NewOIDCIssuer()
+	defer iss.Close()
+	h := NewBearerOIDC(iss.URL, []string{"artifactapi"}).RequireWrites(ok)
+	for _, m := range []string{http.MethodGet, http.MethodHead, http.MethodOptions} {
+		if got := serve(h, m, ""); got != http.StatusNoContent {
+			t.Errorf("%s: status %d, want 204", m, got)
+		}
+	}
+	for _, m := range []string{http.MethodPost, http.MethodPut, http.MethodDelete} {
+		if got := serve(h, m, ""); got != http.StatusUnauthorized {
+			t.Errorf("%s: status %d, want 401", m, got)
+		}
+	}
+}

internal/config/env.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"os"
 	"strconv"
+	"strings"
 )
 
 type Config struct {
@@ -56,6 +57,10 @@ type Config struct {
 	GitHubAppInstallationID string
 	GitHubAppPrivateKey     string
 	GitHubAppPrivateKeyPath string
+
+	// Bearer-JWT auth on configuration writes; empty issuer disables it.
+	OIDCIssuer    string
+	OIDCAudiences []string
 }
 
 func (c *Config) DatabaseDSN() string {
@@ -90,6 +95,17 @@ func Load() (*Config, error) {
 		return nil, fmt.Errorf("invalid GITHUB_SYNC_POLL_INTERVAL: %w", err)
 	}
 
+	oidcIssuer := getenv("ARTIFACTAPI_OIDC_ISSUER", "")
+	var oidcAudiences []string
+	for _, a := range strings.Split(getenv("ARTIFACTAPI_OIDC_AUDIENCE", ""), ",") {
+		if a = strings.TrimSpace(a); a != "" {
+			oidcAudiences = append(oidcAudiences, a)
+		}
+	}
+	if oidcIssuer != "" && len(oidcAudiences) == 0 {
+		return nil, fmt.Errorf("ARTIFACTAPI_OIDC_AUDIENCE is required when ARTIFACTAPI_OIDC_ISSUER is set")
+	}
+
 	cfg := &Config{
 		ListenAddr: getenv("LISTEN_ADDR", ":8000"),
 
@@ -123,6 +139,9 @@ func Load() (*Config, error) {
 		GitHubAppInstallationID: getenv("GITHUB_APP_INSTALLATION_ID", ""),
 		GitHubAppPrivateKey:     getenv("GITHUB_APP_PRIVATE_KEY", ""),
 		GitHubAppPrivateKeyPath: getenv("GITHUB_APP_PRIVATE_KEY_PATH", ""),
+
+		OIDCIssuer:    oidcIssuer,
+		OIDCAudiences: oidcAudiences,
 	}
 
 	return cfg, nil

internal/config/env_test.go

@@ -64,3 +64,20 @@ func TestLoadInvalidPort(t *testing.T) {
 		t.Error("expected error for invalid DBPORT")
 	}
 }
+
+func TestLoadOIDC(t *testing.T) {
+	t.Setenv("ARTIFACTAPI_OIDC_ISSUER", "https://vault.example/v1/identity/oidc")
+	t.Setenv("ARTIFACTAPI_OIDC_AUDIENCE", " a, ,b ")
+	cfg, err := Load()
+	if err != nil {
+		t.Fatalf("load: %v", err)
+	}
+	if len(cfg.OIDCAudiences) != 2 || cfg.OIDCAudiences[0] != "a" || cfg.OIDCAudiences[1] != "b" {
+		t.Errorf("audiences = %q", cfg.OIDCAudiences)
+	}
+
+	t.Setenv("ARTIFACTAPI_OIDC_AUDIENCE", "")
+	if _, err := Load(); err == nil {
+		t.Error("expected error for issuer without audience")
+	}
+}

internal/database/alpine_github_sync.go

@@ -2,11 +2,9 @@ package database
 
 import (
 	"context"
-	"errors"
 	"time"
 
-	"github.com/jackc/pgx/v5"
-
+	"git.unkin.net/unkin/artifactapi/internal/provider"
 	"git.unkin.net/unkin/artifactapi/pkg/models"
 )
 
@@ -30,42 +28,14 @@ func (db *DB) ListGitHubAlpineRemotes(ctx context.Context) ([]models.Remote, err
 	return remotes, rows.Err()
 }
 
-// ClaimGitHubAlpineSyncLease atomically claims the per-remote sync lease. It
-// succeeds only when the remote is due (never synced, or synced longer than
-// freshness ago) and no live lease is held by another replica. A zero freshness
-// (prime scans) ignores the recency gate. The returned etag is the stored
-// releases-list ETag, shared across replicas.
+// ClaimGitHubAlpineSyncLease atomically claims the per-remote github_alpine sync
+// lease. See claimSyncLease.
 func (db *DB) ClaimGitHubAlpineSyncLease(ctx context.Context, remoteName, owner string, freshness, lease time.Duration) (bool, string, error) {
-	row := db.Pool.QueryRow(ctx, `
-		INSERT INTO github_alpine_sync_state AS s (remote_name, sync_lease_owner, sync_lease_expires)
-		VALUES ($1, $2, now() + make_interval(secs => $4))
-		ON CONFLICT (remote_name) DO UPDATE
-			SET sync_lease_owner   = $2,
-			    sync_lease_expires = now() + make_interval(secs => $4)
-			WHERE (s.last_synced_at IS NULL OR s.last_synced_at < now() - make_interval(secs => $3))
-			  AND (s.sync_lease_expires IS NULL OR s.sync_lease_expires < now())
-		RETURNING s.etag
-	`, remoteName, owner, freshness.Seconds(), lease.Seconds())
-
-	var etag string
-	if err := row.Scan(&etag); err != nil {
-		if errors.Is(err, pgx.ErrNoRows) {
-			return false, "", nil
-		}
-		return false, "", err
-	}
-	return true, etag, nil
+	return db.claimSyncLease(ctx, "github_alpine_sync_state", remoteName, owner, freshness, lease)
 }
 
-// ReleaseGitHubAlpineSyncLease records the completed scan and frees the lease.
-// Only the owning replica may release; last_synced_at advances so the next poll
-// waits a full freshness window, and etag is persisted for the next conditional
-// request.
-func (db *DB) ReleaseGitHubAlpineSyncLease(ctx context.Context, remoteName, owner, etag string, syncedAt time.Time) error {
-	_, err := db.Pool.Exec(ctx, `
-		UPDATE github_alpine_sync_state
-		   SET last_synced_at = $3, etag = $4, sync_lease_owner = '', sync_lease_expires = NULL
-		 WHERE remote_name = $1 AND sync_lease_owner = $2
-	`, remoteName, owner, syncedAt, etag)
-	return err
+// ReleaseGitHubAlpineSyncLease records a github_alpine scan outcome and frees the
+// lease. See releaseSyncLease.
+func (db *DB) ReleaseGitHubAlpineSyncLease(ctx context.Context, remoteName, owner string, res provider.SyncResult) error {
+	return db.releaseSyncLease(ctx, "github_alpine_sync_state", remoteName, owner, res)
 }

internal/database/cargo_index.go

@@ -0,0 +1,56 @@
+package database
+
+import (
+	"context"
+	"strings"
+
+	"git.unkin.net/unkin/artifactapi/internal/provider"
+)
+
+func (db *DB) InsertCargoIndexEntry(ctx context.Context, e *provider.CargoIndexEntry) error {
+	_, err := db.Pool.Exec(ctx, `
+		INSERT INTO cargo_index (repo_name, file_path, name, version, line, yanked)
+		VALUES ($1, $2, $3, $4, $5, $6)
+	`, e.RepoName, e.FilePath, e.Name, e.Version, e.Line, e.Yanked)
+	return err
+}
+
+func (db *DB) ListCargoIndexEntries(ctx context.Context, repoName, name string) ([]provider.CargoIndexEntry, error) {
+	rows, err := db.Pool.Query(ctx, `
+		SELECT repo_name, file_path, name, version, line, yanked
+		FROM cargo_index
+		WHERE repo_name = $1 AND lower(name) = $2
+		ORDER BY id
+	`, repoName, strings.ToLower(name))
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	var result []provider.CargoIndexEntry
+	for rows.Next() {
+		var e provider.CargoIndexEntry
+		if err := rows.Scan(&e.RepoName, &e.FilePath, &e.Name, &e.Version, &e.Line, &e.Yanked); err != nil {
+			return nil, err
+		}
+		result = append(result, e)
+	}
+	return result, rows.Err()
+}
+
+// SetCargoYanked reports false when no such crate version exists.
+func (db *DB) SetCargoYanked(ctx context.Context, repoName, name, version string, yanked bool) (bool, error) {
+	tag, err := db.Pool.Exec(ctx, `
+		UPDATE cargo_index SET yanked = $4
+		WHERE repo_name = $1 AND lower(name) = $2 AND version = $3
+	`, repoName, strings.ToLower(name), version, yanked)
+	if err != nil {
+		return false, err
+	}
+	return tag.RowsAffected() > 0, nil
+}
+
+func (db *DB) DeleteCargoIndexEntry(ctx context.Context, repoName, filePath string) error {
+	_, err := db.Pool.Exec(ctx, `DELETE FROM cargo_index WHERE repo_name = $1 AND file_path = $2`, repoName, filePath)
+	return err
+}

internal/database/database_test.go

@@ -425,3 +425,38 @@ func TestRPMMetadata(t *testing.T) {
 		t.Fatalf("list rpm rows: %v %v", len(rows), err)
 	}
 }
+
+func TestCargoIndex(t *testing.T) {
+	requireDB(t)
+	for _, v := range []string{"0.1.0", "0.2.0"} {
+		if err := testDB.InsertCargoIndexEntry(ctx(), &provider.CargoIndexEntry{
+			RepoName: "cargo-db", FilePath: "crates/Unkin-Hello/Unkin-Hello-" + v + ".crate",
+			Name: "Unkin-Hello", Version: v, Line: `{"vers":"` + v + `"}`,
+		}); err != nil {
+			t.Fatal(err)
+		}
+	}
+
+	found, err := testDB.SetCargoYanked(ctx(), "cargo-db", "unkin-hello", "0.1.0", true)
+	if err != nil || !found {
+		t.Fatalf("yank: found=%v err=%v", found, err)
+	}
+	if found, _ := testDB.SetCargoYanked(ctx(), "cargo-db", "unkin-hello", "9.9.9", true); found {
+		t.Error("yank of a missing version reported found")
+	}
+
+	entries, err := testDB.ListCargoIndexEntries(ctx(), "cargo-db", "unkin-hello")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(entries) != 2 || entries[0].Version != "0.1.0" || !entries[0].Yanked || entries[1].Yanked {
+		t.Fatalf("entries = %+v", entries)
+	}
+
+	if err := testDB.DeleteCargoIndexEntry(ctx(), "cargo-db", entries[0].FilePath); err != nil {
+		t.Fatal(err)
+	}
+	if entries, _ = testDB.ListCargoIndexEntries(ctx(), "cargo-db", "UNKIN-HELLO"); len(entries) != 1 {
+		t.Fatalf("after delete: %+v", entries)
+	}
+}

internal/database/deb_github_sync.go

@@ -2,11 +2,9 @@ package database
 
 import (
 	"context"
-	"errors"
 	"time"
 
-	"github.com/jackc/pgx/v5"
-
+	"git.unkin.net/unkin/artifactapi/internal/provider"
 	"git.unkin.net/unkin/artifactapi/pkg/models"
 )
 
@@ -30,41 +28,14 @@ func (db *DB) ListGitHubDebRemotes(ctx context.Context) ([]models.Remote, error)
 	return remotes, rows.Err()
 }
 
-// ClaimGitHubDebSyncLease atomically claims the per-remote sync lease. It
-// succeeds only when the remote is due (never synced, or synced longer than
-// freshness ago) and no live lease is held by another replica. A zero freshness
-// (prime scans) ignores the recency gate. The returned etag is the stored
-// releases-list ETag, shared across replicas.
+// ClaimGitHubDebSyncLease atomically claims the per-remote github_deb sync
+// lease. See claimSyncLease.
 func (db *DB) ClaimGitHubDebSyncLease(ctx context.Context, remoteName, owner string, freshness, lease time.Duration) (bool, string, error) {
-	row := db.Pool.QueryRow(ctx, `
-		INSERT INTO github_deb_sync_state AS s (remote_name, sync_lease_owner, sync_lease_expires)
-		VALUES ($1, $2, now() + make_interval(secs => $4))
-		ON CONFLICT (remote_name) DO UPDATE
-			SET sync_lease_owner   = $2,
-			    sync_lease_expires = now() + make_interval(secs => $4)
-			WHERE (s.last_synced_at IS NULL OR s.last_synced_at < now() - make_interval(secs => $3))
-			  AND (s.sync_lease_expires IS NULL OR s.sync_lease_expires < now())
-		RETURNING s.etag
-	`, remoteName, owner, freshness.Seconds(), lease.Seconds())
-
-	var etag string
-	if err := row.Scan(&etag); err != nil {
-		if errors.Is(err, pgx.ErrNoRows) {
-			return false, "", nil
-		}
-		return false, "", err
-	}
-	return true, etag, nil
+	return db.claimSyncLease(ctx, "github_deb_sync_state", remoteName, owner, freshness, lease)
 }
 
-// ReleaseGitHubDebSyncLease records the completed scan and frees the lease. Only
-// the owning replica may release; last_synced_at advances so the next poll waits
-// a full freshness window, and etag is persisted for the next conditional request.
-func (db *DB) ReleaseGitHubDebSyncLease(ctx context.Context, remoteName, owner, etag string, syncedAt time.Time) error {
-	_, err := db.Pool.Exec(ctx, `
-		UPDATE github_deb_sync_state
-		   SET last_synced_at = $3, etag = $4, sync_lease_owner = '', sync_lease_expires = NULL
-		 WHERE remote_name = $1 AND sync_lease_owner = $2
-	`, remoteName, owner, syncedAt, etag)
-	return err
+// ReleaseGitHubDebSyncLease records a github_deb scan outcome and frees the
+// lease. See releaseSyncLease.
+func (db *DB) ReleaseGitHubDebSyncLease(ctx context.Context, remoteName, owner string, res provider.SyncResult) error {
+	return db.releaseSyncLease(ctx, "github_deb_sync_state", remoteName, owner, res)
 }

internal/database/deb_github_sync_test.go

@@ -4,6 +4,7 @@ import (
 	"testing"
 	"time"
 
+	"git.unkin.net/unkin/artifactapi/internal/provider"
 	"git.unkin.net/unkin/artifactapi/pkg/models"
 )
 
@@ -44,7 +45,7 @@ func TestGitHubDebSyncLease(t *testing.T) {
 		t.Fatal("replica-2 claimed while replica-1 holds the lease")
 	}
 
-	if err := testDB.ReleaseGitHubDebSyncLease(ctx(), name, "replica-1", `"etag-1"`, time.Now()); err != nil {
+	if err := testDB.ReleaseGitHubDebSyncLease(ctx(), name, "replica-1", provider.SyncResult{Etag: `"etag-1"`}); err != nil {
 		t.Fatalf("release: %v", err)
 	}
 

internal/database/github_sync.go

@@ -7,6 +7,8 @@ import (
 
 	"github.com/jackc/pgx/v5"
 
+	"git.unkin.net/unkin/artifactapi/internal/provider"
+
 	"git.unkin.net/unkin/artifactapi/pkg/models"
 )
 
@@ -30,22 +32,35 @@ func (db *DB) ListGitHubRPMRemotes(ctx context.Context) ([]models.Remote, error)
 	return remotes, rows.Err()
 }
 
-// ClaimGitHubSyncLease atomically claims the per-remote sync lease. It succeeds
-// (claimed=true) only when the remote is due — never synced, or synced longer
-// than freshness ago — and no live lease is held by another replica. This bounds
-// total GitHub load to roughly one scan per freshness window regardless of how
-// many replicas poll. The returned etag is the stored releases-list ETag, shared
-// across replicas so a conditional request can short-circuit an unchanged repo.
-// A zero freshness (used for prime scans) ignores the recency gate and claims
-// whenever no live lease is held.
+// ClaimGitHubSyncLease atomically claims the per-remote github_rpm sync lease.
+// See claimSyncLease.
 func (db *DB) ClaimGitHubSyncLease(ctx context.Context, remoteName, owner string, freshness, lease time.Duration) (bool, string, error) {
+	return db.claimSyncLease(ctx, "github_rpm_sync_state", remoteName, owner, freshness, lease)
+}
+
+// ReleaseGitHubSyncLease records a github_rpm scan outcome and frees the lease.
+// See releaseSyncLease.
+func (db *DB) ReleaseGitHubSyncLease(ctx context.Context, remoteName, owner string, res provider.SyncResult) error {
+	return db.releaseSyncLease(ctx, "github_rpm_sync_state", remoteName, owner, res)
+}
+
+// claimSyncLease atomically claims a per-remote sync lease in table. It succeeds
+// (claimed=true) only when the remote is due and no live lease is held by
+// another replica. Due means: a pending retry after a failed scan has reached
+// next_retry_at, or, with no retry pending, the remote was never synced or was
+// synced longer than freshness ago. A zero freshness (prime scans) ignores the
+// recency gate but still honours a pending retry's backoff. The returned etag is
+// the stored releases-list ETag, shared across replicas so a conditional request
+// can short-circuit an unchanged repo.
+func (db *DB) claimSyncLease(ctx context.Context, table, remoteName, owner string, freshness, lease time.Duration) (bool, string, error) {
 	row := db.Pool.QueryRow(ctx, `
-		INSERT INTO github_rpm_sync_state AS s (remote_name, sync_lease_owner, sync_lease_expires)
+		INSERT INTO `+table+` AS s (remote_name, sync_lease_owner, sync_lease_expires)
 		VALUES ($1, $2, now() + make_interval(secs => $4))
 		ON CONFLICT (remote_name) DO UPDATE
 			SET sync_lease_owner   = $2,
 			    sync_lease_expires = now() + make_interval(secs => $4)
-			WHERE (s.last_synced_at IS NULL OR s.last_synced_at < now() - make_interval(secs => $3))
+			WHERE (CASE WHEN s.next_retry_at IS NOT NULL THEN s.next_retry_at <= now()
+			            ELSE s.last_synced_at IS NULL OR s.last_synced_at < now() - make_interval(secs => $3) END)
 			  AND (s.sync_lease_expires IS NULL OR s.sync_lease_expires < now())
 		RETURNING s.etag
 	`, remoteName, owner, freshness.Seconds(), lease.Seconds())
@@ -60,14 +75,27 @@ func (db *DB) ClaimGitHubSyncLease(ctx context.Context, remoteName, owner string
 	return true, etag, nil
 }
 
-// ReleaseGitHubSyncLease records the completed scan and frees the lease. Only the
-// owning replica may release; last_synced_at advances so the next poll waits a
-// full freshness window, and etag is persisted for the next conditional request.
-func (db *DB) ReleaseGitHubSyncLease(ctx context.Context, remoteName, owner, etag string, syncedAt time.Time) error {
+// releaseSyncLease records a scan outcome and frees the lease; only the owning
+// replica may release. Success advances last_synced_at, persists the etag and
+// clears any retry. Failure leaves last_synced_at and etag untouched (the last
+// good metadata keeps serving) and schedules next_retry_at with exponential
+// backoff from the consecutive-failure count, never before res.RetryAt.
+func (db *DB) releaseSyncLease(ctx context.Context, table, remoteName, owner string, res provider.SyncResult) error {
+	var retryAt *time.Time
+	if !res.RetryAt.IsZero() {
+		retryAt = &res.RetryAt
+	}
 	_, err := db.Pool.Exec(ctx, `
-		UPDATE github_rpm_sync_state
-		   SET last_synced_at = $3, etag = $4, sync_lease_owner = '', sync_lease_expires = NULL
+		UPDATE `+table+`
+		   SET last_synced_at = CASE WHEN $3 THEN last_synced_at ELSE now() END,
+		       etag           = CASE WHEN $3 THEN etag ELSE $4 END,
+		       sync_failures  = CASE WHEN $3 THEN sync_failures + 1 ELSE 0 END,
+		       next_retry_at  = CASE WHEN $3 THEN GREATEST(
+		                            now() + make_interval(secs => LEAST($5 * power(2, LEAST(sync_failures, 20)), $6)),
+		                            $7::timestamptz)
+		                        END,
+		       sync_lease_owner = '', sync_lease_expires = NULL
 		 WHERE remote_name = $1 AND sync_lease_owner = $2
-	`, remoteName, owner, syncedAt, etag)
+	`, remoteName, owner, res.Failed, res.Etag, res.Backoff.Seconds(), res.MaxBackoff.Seconds(), retryAt)
 	return err
 }

internal/database/github_sync_test.go

@@ -4,6 +4,7 @@ import (
 	"testing"
 	"time"
 
+	"git.unkin.net/unkin/artifactapi/internal/provider"
 	"git.unkin.net/unkin/artifactapi/pkg/models"
 )
 
@@ -47,7 +48,7 @@ func TestGitHubSyncLease(t *testing.T) {
 	}
 
 	// Replica 1 finishes: record the sync and persist an etag.
-	if err := testDB.ReleaseGitHubSyncLease(ctx(), name, "replica-1", `"etag-1"`, time.Now()); err != nil {
+	if err := testDB.ReleaseGitHubSyncLease(ctx(), name, "replica-1", provider.SyncResult{Etag: `"etag-1"`}); err != nil {
 		t.Fatalf("release: %v", err)
 	}
 
@@ -93,3 +94,116 @@ func TestListGitHubRPMRemotes(t *testing.T) {
 		t.Fatalf("seeded remote %q not returned", name)
 	}
 }
+
+// A failed scan must not count as a sync: the etag and last_synced_at stay put,
+// every claim (prime included) is held off until the backoff elapses, the delay
+// doubles per consecutive failure up to the cap, an upstream retry hint pushes
+// it later, and a success clears the retry state.
+func TestGitHubSyncLeaseFailureBackoff(t *testing.T) {
+	requireDB(t)
+	name := "gh-retry-" + time.Now().Format("150405.000000")
+	seedGitHubRPMRemote(t, name)
+
+	const lease = 15 * time.Minute
+	freshness := time.Hour
+	claim := func(f time.Duration) (bool, string) {
+		t.Helper()
+		ok, etag, err := testDB.ClaimGitHubSyncLease(ctx(), name, "r1", f, lease)
+		if err != nil {
+			t.Fatalf("claim: %v", err)
+		}
+		return ok, etag
+	}
+	release := func(res provider.SyncResult) {
+		t.Helper()
+		if err := testDB.ReleaseGitHubSyncLease(ctx(), name, "r1", res); err != nil {
+			t.Fatalf("release: %v", err)
+		}
+	}
+	state := func() (failures int, retryIn time.Duration, synced *time.Time, etag string) {
+		t.Helper()
+		var next *time.Time
+		var dbNow time.Time
+		if err := testDB.Pool.QueryRow(ctx(), `SELECT sync_failures, next_retry_at, last_synced_at, etag, now() FROM github_rpm_sync_state WHERE remote_name = $1`, name).
+			Scan(&failures, &next, &synced, &etag, &dbNow); err != nil {
+			t.Fatalf("read state: %v", err)
+		}
+		if next != nil {
+			retryIn = next.Sub(dbNow)
+		}
+		return
+	}
+	elapse := func() {
+		t.Helper()
+		if _, err := testDB.Pool.Exec(ctx(), `UPDATE github_rpm_sync_state SET next_retry_at = now() - interval '1 second' WHERE remote_name = $1`, name); err != nil {
+			t.Fatalf("elapse backoff: %v", err)
+		}
+	}
+	failed := provider.SyncResult{Failed: true, Etag: `"ignored"`, Backoff: time.Minute, MaxBackoff: 3 * time.Minute}
+
+	// Last good sync.
+	if ok, _ := claim(freshness); !ok {
+		t.Fatal("first claim failed")
+	}
+	release(provider.SyncResult{Etag: `"good"`})
+	_, _, goodSynced, _ := state()
+
+	// First failure: 60s backoff, sync time and etag untouched.
+	if ok, _ := claim(0); !ok {
+		t.Fatal("prime claim failed")
+	}
+	release(failed)
+	n, in, synced, etag := state()
+	if n != 1 || in < 55*time.Second || in > 65*time.Second {
+		t.Fatalf("after 1st failure: failures=%d retry in %v, want 1 and ~60s", n, in)
+	}
+	if etag != `"good"` || synced == nil || !synced.Equal(*goodSynced) {
+		t.Fatalf("failed scan overwrote sync state: etag=%q synced=%v", etag, synced)
+	}
+	if ok, _ := claim(0); ok {
+		t.Fatal("prime claimed inside the retry backoff")
+	}
+
+	// Backoff elapsed: claimable despite being inside the freshness window,
+	// and the second failure doubles the delay.
+	elapse()
+	if ok, _ := claim(freshness); !ok {
+		t.Fatal("periodic claim refused after backoff elapsed")
+	}
+	release(failed)
+	if n, in, _, _ := state(); n != 2 || in < 115*time.Second || in > 125*time.Second {
+		t.Fatalf("after 2nd failure: failures=%d retry in %v, want 2 and ~120s", n, in)
+	}
+
+	// Third failure caps at MaxBackoff (3m, not 4m).
+	elapse()
+	claim(freshness)
+	release(failed)
+	if n, in, _, _ := state(); n != 3 || in < 175*time.Second || in > 185*time.Second {
+		t.Fatalf("after 3rd failure: failures=%d retry in %v, want 3 and ~180s", n, in)
+	}
+
+	// An upstream rate-limit reset later than the backoff wins.
+	elapse()
+	claim(freshness)
+	hinted := failed
+	hinted.RetryAt = time.Now().Add(20 * time.Minute)
+	release(hinted)
+	if _, in, _, _ := state(); in < 19*time.Minute || in > 21*time.Minute {
+		t.Fatalf("retry hint ignored: retry in %v, want ~20m", in)
+	}
+
+	// Recovery: success persists the new etag and clears the retry, so the
+	// normal freshness window applies again.
+	elapse()
+	if ok, etag := claim(freshness); !ok || etag != `"good"` {
+		t.Fatalf("recovery claim ok=%v etag=%q, want last good etag", ok, etag)
+	}
+	release(provider.SyncResult{Etag: `"new"`})
+	if n, in, _, etag := state(); n != 0 || in != 0 || etag != `"new"` {
+		t.Fatalf("after success: failures=%d retry in %v etag=%q", n, in, etag)
+	}
+	if ok, _ := claim(freshness); ok {
+		t.Fatal("claimed inside freshness window after a successful sync")
+	}
+}

internal/provider/alpine/github.go

@@ -470,7 +470,7 @@ func (p *GitHubProvider) fetchReleases(ctx context.Context, remote models.Remote
 			return nil, "", false, err
 		}
 		if resp.StatusCode != http.StatusOK {
-			return nil, "", false, fmt.Errorf("github releases API %s: status %d", u, resp.StatusCode)
+			return nil, "", false, provider.NewUpstreamStatusError("github releases API "+u, resp)
 		}
 		if page == 1 {
 			newEtag = respEtag

internal/provider/alpine/syncer.go

@@ -28,7 +28,7 @@ type SyncStore interface {
 	provider.RemoteMetadataStore
 	ListGitHubAlpineRemotes(ctx context.Context) ([]models.Remote, error)
 	ClaimGitHubAlpineSyncLease(ctx context.Context, remoteName, owner string, freshness, lease time.Duration) (claimed bool, etag string, err error)
-	ReleaseGitHubAlpineSyncLease(ctx context.Context, remoteName, owner, etag string, syncedAt time.Time) error
+	ReleaseGitHubAlpineSyncLease(ctx context.Context, remoteName, owner string, res provider.SyncResult) error
 }
 
 // SyncConfig tunes the shared syncer. Zero values fall back to safe defaults.
@@ -189,10 +189,11 @@ func (s *Syncer) process(ctx context.Context, job syncJob) {
 		s.mu.Unlock()
 	}()
 
-	freshness := time.Duration(job.remote.MutableTTL) * time.Second
-	if freshness <= 0 {
-		freshness = defaultSyncFreshness
+	ttl := time.Duration(job.remote.MutableTTL) * time.Second
+	if ttl <= 0 {
+		ttl = defaultSyncFreshness
 	}
+	freshness := ttl
 	if job.prime {
 		freshness = 0
 	}
@@ -210,16 +211,13 @@ func (s *Syncer) process(ctx context.Context, job syncJob) {
 	defer cancel()
 
 	newEtag, changed, scanErr := s.prov.scanWithState(scanCtx, job.remote, s.store, etag)
-	releaseEtag := etag
-	if scanErr == nil {
-		releaseEtag = newEtag
-	} else {
+	if scanErr != nil {
 		slog.Error("github_alpine syncer: scan failed", "remote", job.remote.Name, "error", scanErr)
 	}
 
 	relCtx, relCancel := context.WithTimeout(context.WithoutCancel(ctx), 10*time.Second)
 	defer relCancel()
-	if err := s.store.ReleaseGitHubAlpineSyncLease(relCtx, job.remote.Name, s.owner, releaseEtag, time.Now()); err != nil {
+	if err := s.store.ReleaseGitHubAlpineSyncLease(relCtx, job.remote.Name, s.owner, provider.NewSyncResult(newEtag, scanErr, ttl)); err != nil {
 		slog.Warn("github_alpine syncer: release lease", "remote", job.remote.Name, "error", err)
 	}
 

internal/provider/alpine/syncer_test.go

@@ -27,6 +27,7 @@ type fakeSyncStore struct {
 	leaseExp   map[string]time.Time
 	lastSynced map[string]time.Time
 	etags      map[string]string
+	retryAt    map[string]time.Time
 }
 
 func newFakeSyncStore() *fakeSyncStore {
@@ -36,6 +37,7 @@ func newFakeSyncStore() *fakeSyncStore {
 		leaseExp:   map[string]time.Time{},
 		lastSynced: map[string]time.Time{},
 		etags:      map[string]string{},
+		retryAt:    map[string]time.Time{},
 	}
 }
 
@@ -52,6 +54,9 @@ func (f *fakeSyncStore) ClaimGitHubAlpineSyncLease(_ context.Context, name, owne
 	ls, hasLS := f.lastSynced[name]
 	exp, hasExp := f.leaseExp[name]
 	freshOK := !hasLS || now.Sub(ls) >= freshness
+	if ra, pending := f.retryAt[name]; pending {
+		freshOK = !now.Before(ra)
+	}
 	leaseOK := !hasExp || exp.Before(now)
 	if freshOK && leaseOK {
 		f.leaseOwner[name] = owner
@@ -61,14 +66,19 @@ func (f *fakeSyncStore) ClaimGitHubAlpineSyncLease(_ context.Context, name, owne
 	return false, "", nil
 }
 
-func (f *fakeSyncStore) ReleaseGitHubAlpineSyncLease(_ context.Context, name, owner, etag string, syncedAt time.Time) error {
+func (f *fakeSyncStore) ReleaseGitHubAlpineSyncLease(_ context.Context, name, owner string, res provider.SyncResult) error {
 	f.mu.Lock()
 	defer f.mu.Unlock()
 	if f.leaseOwner[name] != owner {
 		return nil
 	}
-	f.lastSynced[name] = syncedAt
-	f.etags[name] = etag
+	if res.Failed {
+		f.retryAt[name] = time.Now().Add(res.Backoff)
+	} else {
+		f.lastSynced[name] = time.Now()
+		f.etags[name] = res.Etag
+		delete(f.retryAt, name)
+	}
 	delete(f.leaseOwner, name)
 	delete(f.leaseExp, name)
 	return nil

internal/provider/cargo/local.go

@@ -0,0 +1,303 @@
+package cargo
+
+import (
+	"context"
+	"crypto/sha256"
+	"encoding/binary"
+	"encoding/hex"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"log/slog"
+	"net/http"
+	"strings"
+
+	"git.unkin.net/unkin/artifactapi/internal/provider"
+)
+
+// publishDep is a dependency as cargo sends it in the publish metadata.
+type publishDep struct {
+	Name               string   `json:"name"`
+	VersionReq         string   `json:"version_req"`
+	Features           []string `json:"features"`
+	Optional           bool     `json:"optional"`
+	DefaultFeatures    bool     `json:"default_features"`
+	Target             *string  `json:"target"`
+	Kind               string   `json:"kind"`
+	Registry           *string  `json:"registry"`
+	ExplicitNameInToml *string  `json:"explicit_name_in_toml"`
+}
+
+// PublishMeta is the JSON half of a `PUT /api/v1/crates/new` body; fields the
+// index does not carry are ignored.
+type PublishMeta struct {
+	Name        string              `json:"name"`
+	Vers        string              `json:"vers"`
+	Deps        []publishDep        `json:"deps"`
+	Features    map[string][]string `json:"features"`
+	Links       *string             `json:"links"`
+	RustVersion *string             `json:"rust_version"`
+}
+
+type indexDep struct {
+	Name            string   `json:"name"`
+	Req             string   `json:"req"`
+	Features        []string `json:"features"`
+	Optional        bool     `json:"optional"`
+	DefaultFeatures bool     `json:"default_features"`
+	Target          *string  `json:"target"`
+	Kind            string   `json:"kind"`
+	Registry        *string  `json:"registry,omitempty"`
+	Package         *string  `json:"package,omitempty"`
+}
+
+// IndexLine is one line of a sparse index file.
+type IndexLine struct {
+	Name        string              `json:"name"`
+	Vers        string              `json:"vers"`
+	Deps        []indexDep          `json:"deps"`
+	Cksum       string              `json:"cksum"`
+	Features    map[string][]string `json:"features"`
+	Features2   map[string][]string `json:"features2,omitempty"`
+	Yanked      bool                `json:"yanked"`
+	Links       *string             `json:"links,omitempty"`
+	V           int                 `json:"v,omitempty"`
+	RustVersion *string             `json:"rust_version,omitempty"`
+}
+
+// ParsePublish splits a publish body: u32le JSON length, JSON, u32le crate length, crate.
+func ParsePublish(body []byte) (PublishMeta, []byte, error) {
+	var meta PublishMeta
+	jsonBytes, rest, err := lengthPrefixed(body)
+	if err != nil {
+		return meta, nil, fmt.Errorf("metadata: %w", err)
+	}
+	crate, rest, err := lengthPrefixed(rest)
+	if err != nil {
+		return meta, nil, fmt.Errorf("crate: %w", err)
+	}
+	if len(rest) != 0 {
+		return meta, nil, errors.New("trailing bytes after crate")
+	}
+	if err := json.Unmarshal(jsonBytes, &meta); err != nil {
+		return meta, nil, fmt.Errorf("metadata: %w", err)
+	}
+	return meta, crate, nil
+}
+
+func lengthPrefixed(b []byte) ([]byte, []byte, error) {
+	if len(b) < 4 {
+		return nil, nil, errors.New("truncated length")
+	}
+	n := binary.LittleEndian.Uint32(b)
+	b = b[4:]
+	if uint64(n) > uint64(len(b)) {
+		return nil, nil, errors.New("truncated body")
+	}
+	return b[:n], b[n:], nil
+}
+
+// NewIndexLine validates the metadata and translates it into index form.
+func NewIndexLine(meta PublishMeta, crate []byte) (IndexLine, error) {
+	if !validName(meta.Name) {
+		return IndexLine{}, fmt.Errorf("invalid crate name %q", meta.Name)
+	}
+	if !validVersion(meta.Vers) {
+		return IndexLine{}, fmt.Errorf("invalid version %q", meta.Vers)
+	}
+	sum := sha256.Sum256(crate)
+	line := IndexLine{
+		Name:        meta.Name,
+		Vers:        meta.Vers,
+		Deps:        make([]indexDep, 0, len(meta.Deps)),
+		Cksum:       hex.EncodeToString(sum[:]),
+		Features:    map[string][]string{},
+		Links:       meta.Links,
+		RustVersion: meta.RustVersion,
+	}
+	for _, d := range meta.Deps {
+		dep := indexDep{
+			Name:            d.Name,
+			Req:             d.VersionReq,
+			Features:        d.Features,
+			Optional:        d.Optional,
+			DefaultFeatures: d.DefaultFeatures,
+			Target:          d.Target,
+			Kind:            d.Kind,
+			Registry:        d.Registry,
+		}
+		if dep.Features == nil {
+			dep.Features = []string{}
+		}
+		if dep.Kind == "" {
+			dep.Kind = "normal"
+		}
+		if d.ExplicitNameInToml != nil && *d.ExplicitNameInToml != "" {
+			pkg := d.Name
+			dep.Name, dep.Package = *d.ExplicitNameInToml, &pkg
+		}
+		line.Deps = append(line.Deps, dep)
+	}
+	// Older cargo cannot parse dep:/?/ feature syntax, so those features live in
+	// features2 behind v:2, as on crates.io.
+	for name, vals := range meta.Features {
+		if vals == nil {
+			vals = []string{}
+		}
+		if usesNewFeatureSyntax(vals) {
+			if line.Features2 == nil {
+				line.Features2 = map[string][]string{}
+			}
+			line.Features2[name] = vals
+			continue
+		}
+		line.Features[name] = vals
+	}
+	if line.Features2 != nil {
+		line.V = 2
+	}
+	return line, nil
+}
+
+func usesNewFeatureSyntax(vals []string) bool {
+	for _, v := range vals {
+		if strings.HasPrefix(v, "dep:") || strings.Contains(v, "?/") {
+			return true
+		}
+	}
+	return false
+}
+
+func validName(name string) bool {
+	if name == "" || len(name) > 64 {
+		return false
+	}
+	for i, c := range name {
+		alpha := (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z')
+		if i == 0 && !alpha {
+			return false
+		}
+		if !alpha && (c < '0' || c > '9') && c != '-' && c != '_' {
+			return false
+		}
+	}
+	return true
+}
+
+func validVersion(v string) bool {
+	if v == "" || len(v) > 128 || !strings.ContainsAny(v[:1], "0123456789") {
+		return false
+	}
+	return strings.Trim(v, "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789.-+") == ""
+}
+
+// IndexPath is the sparse-index file path for a crate name.
+func IndexPath(name string) string {
+	n := strings.ToLower(name)
+	switch len(n) {
+	case 0:
+		return ""
+	case 1:
+		return "1/" + n
+	case 2:
+		return "2/" + n
+	case 3:
+		return "3/" + n[:1] + "/" + n
+	}
+	return n[:2] + "/" + n[2:4] + "/" + n
+}
+
+// CratePath is where a published .crate is stored, matching config.json's dl.
+func CratePath(name, version string) string {
+	return crateDir + name + "/" + name + "-" + version + ".crate"
+}
+
+// RenderIndex joins stored lines into an index file with each yanked flag applied.
+func RenderIndex(entries []provider.CargoIndexEntry) ([]byte, error) {
+	var b strings.Builder
+	for _, e := range entries {
+		var line IndexLine
+		if err := json.Unmarshal([]byte(e.Line), &line); err != nil {
+			return nil, fmt.Errorf("%s %s: %w", e.Name, e.Version, err)
+		}
+		line.Yanked = e.Yanked
+		raw, err := json.Marshal(line)
+		if err != nil {
+			return nil, err
+		}
+		b.Write(raw)
+		b.WriteByte('\n')
+	}
+	return []byte(b.String()), nil
+}
+
+// LocalConfig is config.json for a local registry rooted at base.
+func LocalConfig(base string) map[string]string {
+	return map[string]string{
+		"dl":  base + "/" + crateDir + "{crate}/{crate}-{version}.crate",
+		"api": base,
+	}
+}
+
+func (p *Provider) ServeLocalIndex(w http.ResponseWriter, r *http.Request, files provider.FileStore, repoName, path string) bool {
+	path = strings.TrimLeft(path, "/")
+	if path == "config.json" {
+		w.Header().Set("Content-Type", "application/json")
+		_ = json.NewEncoder(w).Encode(LocalConfig(requestBase(r) + "/api/v1/local/" + repoName))
+		return true
+	}
+	name := path[strings.LastIndex(path, "/")+1:]
+	if name == "" || IndexPath(name) != path {
+		return false
+	}
+
+	reader, ok := files.(provider.CargoIndexReader)
+	if !ok {
+		http.Error(w, "cargo index not available", http.StatusInternalServerError)
+		return true
+	}
+	entries, err := reader.ListCargoIndexEntries(r.Context(), repoName, name)
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return true
+	}
+	if len(entries) == 0 {
+		http.Error(w, "not found", http.StatusNotFound)
+		return true
+	}
+	body, err := RenderIndex(entries)
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return true
+	}
+	w.Header().Set("Content-Type", "text/plain")
+	w.WriteHeader(http.StatusOK)
+	_, _ = w.Write(body)
+	return true
+}
+
+func (p *Provider) GenerateLocalIndex(ctx context.Context, files provider.FileStore, repoName, path string) ([]byte, error) {
+	return nil, fmt.Errorf("cargo local index generation for virtual repos not supported")
+}
+
+func (p *Provider) AfterDelete(ctx context.Context, repoName, storagePath string, db provider.MetadataDeleter) error {
+	deleter, ok := db.(provider.CargoIndexDeleter)
+	if !ok {
+		return nil
+	}
+	if err := deleter.DeleteCargoIndexEntry(ctx, repoName, storagePath); err != nil {
+		slog.Error("cargo index: delete failed", "repo", repoName, "path", storagePath, "error", err)
+		return err
+	}
+	return nil
+}
+
+func requestBase(r *http.Request) string {
+	scheme := "http"
+	if r.TLS != nil {
+		scheme = "https"
+	} else if fwd := r.Header.Get("X-Forwarded-Proto"); fwd != "" {
+		scheme = fwd
+	}
+	return scheme + "://" + r.Host
+}

internal/provider/cargo/local_test.go

@@ -0,0 +1,218 @@
+package cargo
+
+import (
+	"context"
+	"crypto/sha256"
+	"encoding/binary"
+	"encoding/hex"
+	"encoding/json"
+	"net/http/httptest"
+	"strings"
+	"testing"
+
+	"git.unkin.net/unkin/artifactapi/internal/provider"
+)
+
+func publishBody(meta string, crate []byte) []byte {
+	var b []byte
+	b = binary.LittleEndian.AppendUint32(b, uint32(len(meta)))
+	b = append(b, meta...)
+	b = binary.LittleEndian.AppendUint32(b, uint32(len(crate)))
+	return append(b, crate...)
+}
+
+const sampleMeta = `{
+  "name": "unkin-hello", "vers": "0.2.0",
+  "deps": [
+    {"name": "serde", "version_req": "^1", "features": ["derive"], "optional": false,
+     "default_features": true, "target": null, "kind": "normal",
+     "registry": "https://github.com/rust-lang/crates.io-index"},
+    {"name": "rand_core", "version_req": "^0.6", "features": null, "optional": true,
+     "default_features": false, "target": "cfg(unix)", "kind": "dev",
+     "explicit_name_in_toml": "rc"}
+  ],
+  "features": {"default": ["std"], "std": [], "extra": ["dep:rc"], "weak": ["serde?/std"]},
+  "links": null, "rust_version": "1.70", "description": "ignored"
+}`
+
+func TestParsePublishAndIndexLine(t *testing.T) {
+	crate := []byte("fake crate bytes")
+	meta, gotCrate, err := ParsePublish(publishBody(sampleMeta, crate))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if string(gotCrate) != string(crate) {
+		t.Fatalf("crate = %q", gotCrate)
+	}
+	line, err := NewIndexLine(meta, crate)
+	if err != nil {
+		t.Fatal(err)
+	}
+	sum := sha256.Sum256(crate)
+	if line.Cksum != hex.EncodeToString(sum[:]) {
+		t.Errorf("cksum = %s", line.Cksum)
+	}
+
+	raw, _ := json.Marshal(line)
+	var got map[string]any
+	_ = json.Unmarshal(raw, &got)
+	if _, ok := got["version_req"]; ok {
+		t.Error("publish-only field leaked into index line")
+	}
+	if got["v"] != float64(2) {
+		t.Errorf("v = %v, want 2 with features2 present", got["v"])
+	}
+	if got["rust_version"] != "1.70" {
+		t.Errorf("rust_version = %v", got["rust_version"])
+	}
+	if _, ok := line.Features["extra"]; ok {
+		t.Error("dep: feature must move to features2")
+	}
+	if len(line.Features2) != 2 || len(line.Features) != 2 {
+		t.Errorf("features = %v features2 = %v", line.Features, line.Features2)
+	}
+
+	deps := got["deps"].([]any)
+	serde := deps[0].(map[string]any)
+	if serde["req"] != "^1" || serde["registry"] != "https://github.com/rust-lang/crates.io-index" || serde["target"] != nil {
+		t.Errorf("serde dep = %v", serde)
+	}
+	if _, ok := serde["package"]; ok {
+		t.Error("package set without a rename")
+	}
+	renamed := deps[1].(map[string]any)
+	if renamed["name"] != "rc" || renamed["package"] != "rand_core" || renamed["kind"] != "dev" {
+		t.Errorf("renamed dep = %v", renamed)
+	}
+	if f, ok := renamed["features"].([]any); !ok || len(f) != 0 {
+		t.Errorf("null features must render as [], got %v", renamed["features"])
+	}
+}
+
+func TestIndexLineNoNewFeaturesOmitsV(t *testing.T) {
+	line, err := NewIndexLine(PublishMeta{Name: "a", Vers: "1.0.0", Features: map[string][]string{"x": nil}}, nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	raw, _ := json.Marshal(line)
+	s := string(raw)
+	for _, bad := range []string{`"v":`, `"features2"`, `"links"`} {
+		if strings.Contains(s, bad) {
+			t.Errorf("%s present in %s", bad, s)
+		}
+	}
+	if !strings.Contains(s, `"deps":[]`) || !strings.Contains(s, `"features":{"x":[]}`) {
+		t.Errorf("deps/features must be non-null: %s", s)
+	}
+}
+
+func TestParsePublishRejectsMalformed(t *testing.T) {
+	good := publishBody(`{"name":"a","vers":"1.0.0"}`, []byte("c"))
+	for name, body := range map[string][]byte{
+		"empty":     nil,
+		"short":     good[:len(good)-1],
+		"trailing":  append(append([]byte{}, good...), 'x'),
+		"bad json":  publishBody(`{`, []byte("c")),
+		"no length": good[:6],
+	} {
+		if _, _, err := ParsePublish(body); err == nil {
+			t.Errorf("%s: expected error", name)
+		}
+	}
+}
+
+func TestNewIndexLineValidation(t *testing.T) {
+	for _, m := range []PublishMeta{
+		{Name: "", Vers: "1.0.0"},
+		{Name: "1abc", Vers: "1.0.0"},
+		{Name: "../x", Vers: "1.0.0"},
+		{Name: "ok", Vers: "1.0.0/../../x"},
+		{Name: "ok", Vers: ""},
+		{Name: strings.Repeat("a", 65), Vers: "1.0.0"},
+	} {
+		if _, err := NewIndexLine(m, nil); err == nil {
+			t.Errorf("%q@%q accepted", m.Name, m.Vers)
+		}
+	}
+	if _, err := NewIndexLine(PublishMeta{Name: "Foo_bar-2", Vers: "1.0.0-rc.1+build.5"}, nil); err != nil {
+		t.Error(err)
+	}
+}
+
+func TestIndexPath(t *testing.T) {
+	for name, want := range map[string]string{
+		"a": "1/a", "ab": "2/ab", "abc": "3/a/abc", "Serde": "se/rd/serde", "unkin-hello": "un/ki/unkin-hello",
+	} {
+		if got := IndexPath(name); got != want {
+			t.Errorf("IndexPath(%q) = %q, want %q", name, got, want)
+		}
+	}
+}
+
+type fakeIndex struct {
+	entries []provider.CargoIndexEntry
+	asked   string
+}
+
+func (f *fakeIndex) ListCargoIndexEntries(_ context.Context, _, name string) ([]provider.CargoIndexEntry, error) {
+	f.asked = name
+	return f.entries, nil
+}
+func (f *fakeIndex) ListFilesByPrefix(context.Context, string, string) ([]provider.FileEntry, error) {
+	return nil, nil
+}
+func (f *fakeIndex) ListPackages(context.Context, string) ([]string, error) { return nil, nil }
+
+func TestServeLocalIndex(t *testing.T) {
+	line, _ := NewIndexLine(PublishMeta{Name: "unkin-hello", Vers: "0.1.0"}, []byte("x"))
+	raw, _ := json.Marshal(line)
+	files := &fakeIndex{entries: []provider.CargoIndexEntry{
+		{Name: "unkin-hello", Version: "0.1.0", Line: string(raw), Yanked: true},
+		{Name: "unkin-hello", Version: "0.2.0", Line: strings.Replace(string(raw), "0.1.0", "0.2.0", 1)},
+	}}
+	p := &Provider{}
+
+	rec := httptest.NewRecorder()
+	if !p.ServeLocalIndex(rec, httptest.NewRequest("GET", "http://aa.example/x", nil), files, "crates-local", "un/ki/unkin-hello") {
+		t.Fatal("index path not served")
+	}
+	lines := strings.Split(strings.TrimSpace(rec.Body.String()), "\n")
+	if len(lines) != 2 || !strings.Contains(lines[0], `"yanked":true`) || !strings.Contains(lines[1], `"yanked":false`) {
+		t.Errorf("index body = %q", rec.Body.String())
+	}
+	if files.asked != "unkin-hello" {
+		t.Errorf("looked up %q", files.asked)
+	}
+
+	rec = httptest.NewRecorder()
+	req := httptest.NewRequest("GET", "http://aa.example/config.json", nil)
+	req.Header.Set("X-Forwarded-Proto", "https")
+	p.ServeLocalIndex(rec, req, files, "crates-local", "config.json")
+	var cfg map[string]string
+	_ = json.Unmarshal(rec.Body.Bytes(), &cfg)
+	if cfg["api"] != "https://aa.example/api/v1/local/crates-local" ||
+		cfg["dl"] != "https://aa.example/api/v1/local/crates-local/crates/{crate}/{crate}-{version}.crate" {
+		t.Errorf("config = %v", cfg)
+	}
+
+	for _, path := range []string{"crates/unkin-hello/unkin-hello-0.1.0.crate", "xx/ki/unkin-hello", ""} {
+		if p.ServeLocalIndex(httptest.NewRecorder(), httptest.NewRequest("GET", "/", nil), files, "r", path) {
+			t.Errorf("%q should fall through", path)
+		}
+	}
+
+	files.entries = nil
+	rec = httptest.NewRecorder()
+	p.ServeLocalIndex(rec, httptest.NewRequest("GET", "/", nil), files, "r", "3/a/abc")
+	if rec.Code != 404 {
+		t.Errorf("unknown crate code = %d", rec.Code)
+	}
+}
+
+func TestCratePathMatchesDL(t *testing.T) {
+	dl := LocalConfig("http://h/api/v1/local/r")["dl"]
+	want := strings.NewReplacer("{crate}", "unkin-hello", "{version}", "0.1.0").Replace(dl)
+	if got := "http://h/api/v1/local/r/" + CratePath("unkin-hello", "0.1.0"); got != want {
+		t.Errorf("CratePath = %q, dl expands to %q", got, want)
+	}
+}

internal/provider/cargo_index.go

@@ -0,0 +1,24 @@
+package provider
+
+import "context"
+
+// CargoIndexEntry is one published crate version in a local cargo registry.
+// Line is the sparse-index JSON line; Yanked is applied when it is served.
+type CargoIndexEntry struct {
+	RepoName string
+	FilePath string
+	Name     string
+	Version  string
+	Line     string
+	Yanked   bool
+}
+
+// CargoIndexReader lists every version of one crate (matched case-insensitively).
+// *database.DB satisfies it and CargoIndexDeleter.
+type CargoIndexReader interface {
+	ListCargoIndexEntries(ctx context.Context, repoName, name string) ([]CargoIndexEntry, error)
+}
+
+type CargoIndexDeleter interface {
+	DeleteCargoIndexEntry(ctx context.Context, repoName, filePath string) error
+}

internal/provider/deb/github.go

@@ -431,7 +431,7 @@ func (p *GitHubProvider) fetchReleases(ctx context.Context, remote models.Remote
 			return nil, "", false, err
 		}
 		if resp.StatusCode != http.StatusOK {
-			return nil, "", false, fmt.Errorf("github releases API %s: status %d", u, resp.StatusCode)
+			return nil, "", false, provider.NewUpstreamStatusError("github releases API "+u, resp)
 		}
 		if page == 1 {
 			newEtag = respEtag

internal/provider/deb/syncer.go

@@ -28,7 +28,7 @@ type SyncStore interface {
 	provider.RemoteMetadataStore
 	ListGitHubDebRemotes(ctx context.Context) ([]models.Remote, error)
 	ClaimGitHubDebSyncLease(ctx context.Context, remoteName, owner string, freshness, lease time.Duration) (claimed bool, etag string, err error)
-	ReleaseGitHubDebSyncLease(ctx context.Context, remoteName, owner, etag string, syncedAt time.Time) error
+	ReleaseGitHubDebSyncLease(ctx context.Context, remoteName, owner string, res provider.SyncResult) error
 }
 
 // SyncConfig tunes the shared syncer. Zero values fall back to safe defaults.
@@ -189,10 +189,11 @@ func (s *Syncer) process(ctx context.Context, job syncJob) {
 		s.mu.Unlock()
 	}()
 
-	freshness := time.Duration(job.remote.MutableTTL) * time.Second
-	if freshness <= 0 {
-		freshness = defaultSyncFreshness
+	ttl := time.Duration(job.remote.MutableTTL) * time.Second
+	if ttl <= 0 {
+		ttl = defaultSyncFreshness
 	}
+	freshness := ttl
 	if job.prime {
 		freshness = 0
 	}
@@ -210,16 +211,13 @@ func (s *Syncer) process(ctx context.Context, job syncJob) {
 	defer cancel()
 
 	newEtag, changed, scanErr := s.prov.scanWithState(scanCtx, job.remote, s.store, etag)
-	releaseEtag := etag
-	if scanErr == nil {
-		releaseEtag = newEtag
-	} else {
+	if scanErr != nil {
 		slog.Error("github_deb syncer: scan failed", "remote", job.remote.Name, "error", scanErr)
 	}
 
 	relCtx, relCancel := context.WithTimeout(context.WithoutCancel(ctx), 10*time.Second)
 	defer relCancel()
-	if err := s.store.ReleaseGitHubDebSyncLease(relCtx, job.remote.Name, s.owner, releaseEtag, time.Now()); err != nil {
+	if err := s.store.ReleaseGitHubDebSyncLease(relCtx, job.remote.Name, s.owner, provider.NewSyncResult(newEtag, scanErr, ttl)); err != nil {
 		slog.Warn("github_deb syncer: release lease", "remote", job.remote.Name, "error", err)
 	}
 

internal/provider/deb/syncer_test.go

@@ -27,6 +27,7 @@ type fakeSyncStore struct {
 	leaseExp   map[string]time.Time
 	lastSynced map[string]time.Time
 	etags      map[string]string
+	retryAt    map[string]time.Time
 }
 
 func newFakeSyncStore() *fakeSyncStore {
@@ -36,6 +37,7 @@ func newFakeSyncStore() *fakeSyncStore {
 		leaseExp:   map[string]time.Time{},
 		lastSynced: map[string]time.Time{},
 		etags:      map[string]string{},
+		retryAt:    map[string]time.Time{},
 	}
 }
 
@@ -52,6 +54,9 @@ func (f *fakeSyncStore) ClaimGitHubDebSyncLease(_ context.Context, name, owner s
 	ls, hasLS := f.lastSynced[name]
 	exp, hasExp := f.leaseExp[name]
 	freshOK := !hasLS || now.Sub(ls) >= freshness
+	if ra, pending := f.retryAt[name]; pending {
+		freshOK = !now.Before(ra)
+	}
 	leaseOK := !hasExp || exp.Before(now)
 	if freshOK && leaseOK {
 		f.leaseOwner[name] = owner
@@ -61,14 +66,19 @@ func (f *fakeSyncStore) ClaimGitHubDebSyncLease(_ context.Context, name, owner s
 	return false, "", nil
 }
 
-func (f *fakeSyncStore) ReleaseGitHubDebSyncLease(_ context.Context, name, owner, etag string, syncedAt time.Time) error {
+func (f *fakeSyncStore) ReleaseGitHubDebSyncLease(_ context.Context, name, owner string, res provider.SyncResult) error {
 	f.mu.Lock()
 	defer f.mu.Unlock()
 	if f.leaseOwner[name] != owner {
 		return nil
 	}
-	f.lastSynced[name] = syncedAt
-	f.etags[name] = etag
+	if res.Failed {
+		f.retryAt[name] = time.Now().Add(res.Backoff)
+	} else {
+		f.lastSynced[name] = time.Now()
+		f.etags[name] = res.Etag
+		delete(f.retryAt, name)
+	}
 	delete(f.leaseOwner, name)
 	delete(f.leaseExp, name)
 	return nil

internal/provider/rpm/github.go

@@ -447,7 +447,7 @@ func (p *GitHubProvider) fetchReleases(ctx context.Context, remote models.Remote
 			return nil, "", false, err
 		}
 		if resp.StatusCode != http.StatusOK {
-			return nil, "", false, fmt.Errorf("github releases API %s: status %d", u, resp.StatusCode)
+			return nil, "", false, provider.NewUpstreamStatusError("github releases API "+u, resp)
 		}
 		if page == 1 {
 			newEtag = respEtag

internal/provider/rpm/github_test.go

@@ -78,6 +78,7 @@ type githubFixture struct {
 	notModHit   int               // releases-list requests answered 304
 	releaseAuth string            // Authorization header seen on the last releases request
 	assetAuth   string            // Authorization header seen on the last asset request
+	failStatus  int               // when set, the releases list answers this status (rate-limit style)
 	mu          sync.Mutex
 }
 
@@ -100,6 +101,14 @@ func newGitHubFixture(t *testing.T, withDigest bool) *githubFixture {
 		f.mu.Lock()
 		f.releasesHit++
 		f.releaseAuth = r.Header.Get("Authorization")
+		if f.failStatus != 0 {
+			status := f.failStatus
+			f.mu.Unlock()
+			w.Header().Set("X-RateLimit-Remaining", "0")
+			w.Header().Set("X-RateLimit-Reset", strconv.FormatInt(time.Now().Add(30*time.Second).Unix(), 10))
+			http.Error(w, "API rate limit exceeded", status)
+			return
+		}
 		etag := f.etag
 		if etag != "" && r.Header.Get("If-None-Match") == etag {
 			f.notModHit++

internal/provider/rpm/syncer.go

@@ -35,7 +35,7 @@ type SyncStore interface {
 	provider.RemoteMetadataStore
 	ListGitHubRPMRemotes(ctx context.Context) ([]models.Remote, error)
 	ClaimGitHubSyncLease(ctx context.Context, remoteName, owner string, freshness, lease time.Duration) (claimed bool, etag string, err error)
-	ReleaseGitHubSyncLease(ctx context.Context, remoteName, owner, etag string, syncedAt time.Time) error
+	ReleaseGitHubSyncLease(ctx context.Context, remoteName, owner string, res provider.SyncResult) error
 }
 
 // SyncConfig tunes the shared syncer. Zero values fall back to safe defaults.
@@ -205,10 +205,11 @@ func (s *Syncer) process(ctx context.Context, job syncJob) {
 		s.mu.Unlock()
 	}()
 
-	freshness := time.Duration(job.remote.MutableTTL) * time.Second
-	if freshness <= 0 {
-		freshness = defaultSyncFreshness
+	ttl := time.Duration(job.remote.MutableTTL) * time.Second
+	if ttl <= 0 {
+		ttl = defaultSyncFreshness
 	}
+	freshness := ttl
 	if job.prime {
 		freshness = 0 // prime ignores the recency gate but still respects a live lease
 	}
@@ -226,18 +227,15 @@ func (s *Syncer) process(ctx context.Context, job syncJob) {
 	defer cancel()
 
 	newEtag, changed, scanErr := s.prov.scanWithState(scanCtx, job.remote, s.store, etag)
-	releaseEtag := etag
-	if scanErr == nil {
-		releaseEtag = newEtag
-	} else {
+	if scanErr != nil {
 		slog.Error("github_rpm syncer: scan failed", "remote", job.remote.Name, "error", scanErr)
 	}
 
 	// Release on a detached context so a clean shutdown mid-scan still frees the
-	// lease and advances last_synced_at (otherwise it simply expires).
+	// lease and records the outcome (otherwise the lease simply expires).
 	relCtx, relCancel := context.WithTimeout(context.WithoutCancel(ctx), 10*time.Second)
 	defer relCancel()
-	if err := s.store.ReleaseGitHubSyncLease(relCtx, job.remote.Name, s.owner, releaseEtag, time.Now()); err != nil {
+	if err := s.store.ReleaseGitHubSyncLease(relCtx, job.remote.Name, s.owner, provider.NewSyncResult(newEtag, scanErr, ttl)); err != nil {
 		slog.Warn("github_rpm syncer: release lease", "remote", job.remote.Name, "error", err)
 	}
 

internal/provider/rpm/syncer_test.go

@@ -27,6 +27,8 @@ type fakeSyncStore struct {
 	leaseExp   map[string]time.Time
 	lastSynced map[string]time.Time
 	etags      map[string]string
+	retryAt    map[string]time.Time
+	lastResult provider.SyncResult
 }
 
 func newFakeSyncStore() *fakeSyncStore {
@@ -36,6 +38,7 @@ func newFakeSyncStore() *fakeSyncStore {
 		leaseExp:   map[string]time.Time{},
 		lastSynced: map[string]time.Time{},
 		etags:      map[string]string{},
+		retryAt:    map[string]time.Time{},
 	}
 }
 
@@ -52,6 +55,9 @@ func (f *fakeSyncStore) ClaimGitHubSyncLease(_ context.Context, name, owner stri
 	ls, hasLS := f.lastSynced[name]
 	exp, hasExp := f.leaseExp[name]
 	freshOK := !hasLS || now.Sub(ls) >= freshness
+	if ra, pending := f.retryAt[name]; pending {
+		freshOK = !now.Before(ra)
+	}
 	leaseOK := !hasExp || exp.Before(now)
 	if freshOK && leaseOK {
 		f.leaseOwner[name] = owner
@@ -61,14 +67,20 @@ func (f *fakeSyncStore) ClaimGitHubSyncLease(_ context.Context, name, owner stri
 	return false, "", nil
 }
 
-func (f *fakeSyncStore) ReleaseGitHubSyncLease(_ context.Context, name, owner, etag string, syncedAt time.Time) error {
+func (f *fakeSyncStore) ReleaseGitHubSyncLease(_ context.Context, name, owner string, res provider.SyncResult) error {
 	f.mu.Lock()
 	defer f.mu.Unlock()
 	if f.leaseOwner[name] != owner {
 		return nil
 	}
-	f.lastSynced[name] = syncedAt
-	f.etags[name] = etag
+	f.lastResult = res
+	if res.Failed {
+		f.retryAt[name] = time.Now().Add(res.Backoff)
+	} else {
+		f.lastSynced[name] = time.Now()
+		f.etags[name] = res.Etag
+		delete(f.retryAt, name)
+	}
 	delete(f.leaseOwner, name)
 	delete(f.leaseExp, name)
 	return nil
@@ -310,3 +322,80 @@ func TestSyncerPrimeBypassesRecencyPeriodicDoesNot(t *testing.T) {
 		t.Fatalf("periodic scan ran inside recency window: %d -> %d releases calls", releasesAfterPrime, fx.releasesHit)
 	}
 }
+
+// A rate-limited scan is not recorded as a sync: the last good repodata keeps
+// serving, the retry honours the upstream reset hint and backoff, and once the
+// upstream recovers the next poll after the backoff re-syncs without waiting
+// out mutable_ttl.
+func TestSyncerFailedScanRetriesAfterBackoff(t *testing.T) {
+	fx := newGitHubFixture(t, true)
+	fx.etag = `"v1"`
+	store := newFakeSyncStore()
+	p := newTestProvider()
+	s := newSyncer(store, p, testSyncConfig())
+	remote := fx.remote()
+	bg := context.Background()
+
+	s.process(bg, syncJob{remote: remote, prime: true})
+	if rows, _ := store.ListRPMMetadataEntries(bg, remote.Name); len(rows) != 1 {
+		t.Fatalf("prime did not derive: %d rows", len(rows))
+	}
+
+	// mutable_ttl elapses while GitHub is rate-limiting.
+	fx.mu.Lock()
+	fx.failStatus = http.StatusForbidden
+	fx.etag = `"v2"`
+	fx.mu.Unlock()
+	store.mu.Lock()
+	store.lastSynced[remote.Name] = time.Now().Add(-2 * time.Hour)
+	store.mu.Unlock()
+
+	s.process(bg, syncJob{remote: remote})
+	res := store.lastResult
+	if !res.Failed {
+		t.Fatal("403 scan was recorded as a successful sync")
+	}
+	if until := time.Until(res.RetryAt); until < 20*time.Second || until > 40*time.Second {
+		t.Fatalf("retry hint from X-RateLimit-Reset not carried: retry in %v", until)
+	}
+	if res.Backoff != time.Minute || res.MaxBackoff >= time.Duration(remote.MutableTTL)*time.Second {
+		t.Fatalf("backoff %v cap %v, want 1m first retry capped below mutable_ttl", res.Backoff, res.MaxBackoff)
+	}
+	if store.etags[remote.Name] != `"v1"` {
+		t.Fatalf("failed scan replaced the etag: %q", store.etags[remote.Name])
+	}
+
+	rec := httptest.NewRecorder()
+	req := httptest.NewRequest(http.MethodGet, "/api/v1/remote/acme-rpm/repodata/repomd.xml", nil)
+	p.ServeRemote(rec, req, remote, "repodata/repomd.xml", "https://x", store)
+	if rec.Code != http.StatusOK {
+		t.Fatalf("last good repodata not served during failure: %d %s", rec.Code, rec.Body.String())
+	}
+	if rows, _ := store.ListRPMMetadataEntries(bg, remote.Name); len(rows) != 1 {
+		t.Fatalf("failed scan dropped cached metadata: %d rows", len(rows))
+	}
+
+	// Inside the backoff nothing is retried.
+	hits := fx.releasesHit
+	s.process(bg, syncJob{remote: remote})
+	if fx.releasesHit != hits {
+		t.Fatal("scan retried inside the backoff window")
+	}
+
+	// Upstream recovers and the backoff elapses: the next poll re-syncs.
+	fx.mu.Lock()
+	fx.failStatus = 0
+	fx.rpmBytes["other-9-9.aarch64.rpm"] = testsupport.MinimalRPM("other", "9", "9", "aarch64")
+	fx.mu.Unlock()
+	store.mu.Lock()
+	store.retryAt[remote.Name] = time.Now().Add(-time.Second)
+	store.mu.Unlock()
+
+	s.process(bg, syncJob{remote: remote})
+	if store.lastResult.Failed || store.etags[remote.Name] != `"v2"` {
+		t.Fatalf("recovery scan not recorded: failed=%v etag=%q", store.lastResult.Failed, store.etags[remote.Name])
+	}
+	if rows, _ := store.ListRPMMetadataEntries(bg, remote.Name); len(rows) != 2 {
+		t.Fatalf("recovery did not refresh metadata: %d rows", len(rows))
+	}
+}

internal/provider/syncretry.go

@@ -0,0 +1,75 @@
+package provider
+
+import (
+	"errors"
+	"fmt"
+	"net/http"
+	"strconv"
+	"time"
+)
+
+const (
+	syncRetryBase = time.Minute
+	syncRetryMax  = 10 * time.Minute
+)
+
+// UpstreamStatusError is a non-success upstream response. RetryAt is the
+// upstream's own retry hint (Retry-After, or X-RateLimit-Reset once the quota
+// is exhausted); zero when it gave none.
+type UpstreamStatusError struct {
+	URL     string
+	Status  int
+	RetryAt time.Time
+}
+
+func (e *UpstreamStatusError) Error() string {
+	return fmt.Sprintf("%s: status %d", e.URL, e.Status)
+}
+
+// NewUpstreamStatusError wraps a non-success response, capturing its retry hint.
+func NewUpstreamStatusError(url string, resp *http.Response) *UpstreamStatusError {
+	e := &UpstreamStatusError{URL: url, Status: resp.StatusCode}
+	if ra := resp.Header.Get("Retry-After"); ra != "" {
+		if secs, err := strconv.Atoi(ra); err == nil {
+			e.RetryAt = time.Now().Add(time.Duration(secs) * time.Second)
+		} else if t, err := http.ParseTime(ra); err == nil {
+			e.RetryAt = t
+		}
+	} else if resp.Header.Get("X-RateLimit-Remaining") == "0" {
+		if reset, err := strconv.ParseInt(resp.Header.Get("X-RateLimit-Reset"), 10, 64); err == nil {
+			e.RetryAt = time.Unix(reset, 0)
+		}
+	}
+	return e
+}
+
+// SyncResult is a background scan's outcome, recorded when its sync lease is
+// released. A failed scan keeps the prior sync time and ETag and schedules a
+// retry after Backoff, doubled per consecutive failure up to MaxBackoff, and
+// never earlier than RetryAt.
+type SyncResult struct {
+	Etag       string
+	Failed     bool
+	RetryAt    time.Time
+	Backoff    time.Duration
+	MaxBackoff time.Duration
+}
+
+// NewSyncResult builds the result for a scan against a remote with the given
+// mutable_ttl. The retry cap stays well below ttl, and an upstream hint is
+// clamped to ttl so a bogus reset can never stall the remote longer than a
+// normal sync interval would.
+func NewSyncResult(etag string, scanErr error, ttl time.Duration) SyncResult {
+	if scanErr == nil {
+		return SyncResult{Etag: etag}
+	}
+	res := SyncResult{Failed: true, Backoff: syncRetryBase, MaxBackoff: min(syncRetryMax, max(syncRetryBase, ttl/4))}
+	var se *UpstreamStatusError
+	if errors.As(scanErr, &se) && !se.RetryAt.IsZero() {
+		res.RetryAt = se.RetryAt
+		if limit := time.Now().Add(ttl); res.RetryAt.After(limit) {
+			res.RetryAt = limit
+		}
+	}
+	return res
+}

internal/provider/syncretry_test.go

@@ -0,0 +1,63 @@
+package provider
+
+import (
+	"errors"
+	"fmt"
+	"net/http"
+	"strconv"
+	"testing"
+	"time"
+)
+
+func TestNewUpstreamStatusErrorRetryHint(t *testing.T) {
+	reset := time.Now().Add(15 * time.Minute).Truncate(time.Second)
+	cases := []struct {
+		name   string
+		header map[string]string
+		want   time.Duration // 0 = no hint
+	}{
+		{"retry-after seconds", map[string]string{"Retry-After": "90"}, 90 * time.Second},
+		{"retry-after date", map[string]string{"Retry-After": reset.UTC().Format(http.TimeFormat)}, 15 * time.Minute},
+		{"quota exhausted", map[string]string{"X-RateLimit-Remaining": "0", "X-RateLimit-Reset": strconv.FormatInt(reset.Unix(), 10)}, 15 * time.Minute},
+		{"quota left is not a hint", map[string]string{"X-RateLimit-Remaining": "12", "X-RateLimit-Reset": strconv.FormatInt(reset.Unix(), 10)}, 0},
+		{"no headers", nil, 0},
+	}
+	for _, c := range cases {
+		t.Run(c.name, func(t *testing.T) {
+			resp := &http.Response{StatusCode: http.StatusForbidden, Header: http.Header{}}
+			for k, v := range c.header {
+				resp.Header.Set(k, v)
+			}
+			e := NewUpstreamStatusError("u", resp)
+			if c.want == 0 {
+				if !e.RetryAt.IsZero() {
+					t.Fatalf("unexpected hint %v", e.RetryAt)
+				}
+				return
+			}
+			if d := time.Until(e.RetryAt) - c.want; d < -2*time.Second || d > 2*time.Second {
+				t.Fatalf("retry in %v, want ~%v", time.Until(e.RetryAt), c.want)
+			}
+		})
+	}
+}
+
+func TestNewSyncResult(t *testing.T) {
+	if r := NewSyncResult(`"e"`, nil, time.Hour); r.Failed || r.Etag != `"e"` {
+		t.Fatalf("success result = %+v", r)
+	}
+
+	r := NewSyncResult(`"e"`, errors.New("boom"), time.Hour)
+	if !r.Failed || r.Backoff != time.Minute || r.MaxBackoff != 10*time.Minute || !r.RetryAt.IsZero() {
+		t.Fatalf("plain failure = %+v, want 1m backoff capped at 10m, no hint", r)
+	}
+	if r := NewSyncResult("", errors.New("boom"), 5*time.Minute); r.MaxBackoff != time.Minute+15*time.Second {
+		t.Fatalf("short ttl cap = %v, want ttl/4", r.MaxBackoff)
+	}
+
+	far := &UpstreamStatusError{Status: 403, RetryAt: time.Now().Add(3 * time.Hour)}
+	r = NewSyncResult("", fmt.Errorf("scan: %w", far), time.Hour)
+	if until := time.Until(r.RetryAt); until > time.Hour || until < 59*time.Minute {
+		t.Fatalf("wrapped hint not clamped to ttl: retry in %v", until)
+	}
+}

internal/server/middleware.go

@@ -12,7 +12,7 @@ func cors(next http.Handler) http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		w.Header().Set("Access-Control-Allow-Origin", "*")
 		w.Header().Set("Access-Control-Allow-Methods", "GET, POST, PUT, DELETE, OPTIONS")
-		w.Header().Set("Access-Control-Allow-Headers", "Content-Type")
+		w.Header().Set("Access-Control-Allow-Headers", "Content-Type, Authorization")
 		if r.Method == http.MethodOptions {
 			w.WriteHeader(http.StatusNoContent)
 			return

internal/server/oidc_test.go

@@ -0,0 +1,80 @@
+package server
+
+import (
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+	"time"
+
+	"git.unkin.net/unkin/artifactapi/internal/testsupport"
+)
+
+func TestServerOIDCWriteAuth(t *testing.T) {
+	requireStack(t)
+	iss := testsupport.NewOIDCIssuer()
+	defer iss.Close()
+
+	cfg := *testSrv.cfg
+	cfg.OIDCIssuer = iss.URL
+	cfg.OIDCAudiences = []string{"artifactapi"}
+	s := *testSrv
+	s.cfg = &cfg
+	ts := httptest.NewServer(s.routes())
+	defer ts.Close()
+
+	good := iss.Token(nil, "artifactapi", "ci", time.Hour)
+	do := func(method, path, body, token string) int {
+		t.Helper()
+		rq, _ := http.NewRequest(method, ts.URL+path, strings.NewReader(body))
+		rq.Header.Set("Content-Type", "application/json")
+		if token != "" {
+			rq.Header.Set("Authorization", "Bearer "+token)
+		}
+		resp, err := http.DefaultClient.Do(rq)
+		if err != nil {
+			t.Fatalf("%s %s: %v", method, path, err)
+		}
+		_, _ = io.Copy(io.Discard, resp.Body)
+		_ = resp.Body.Close()
+		return resp.StatusCode
+	}
+	expect := func(want int, method, path, body, token string) {
+		t.Helper()
+		if got := do(method, path, body, token); got != want {
+			t.Errorf("%s %s: status %d, want %d", method, path, got, want)
+		}
+	}
+
+	remote := `{"name":"srv-oidc","package_type":"generic","repo_type":"local"}`
+	virtual := `{"name":"srv-oidc-v","package_type":"generic","members":["srv-oidc"]}`
+
+	expect(401, "POST", "/api/v2/remotes", remote, "")
+	expect(401, "POST", "/api/v2/remotes", remote, iss.Token(nil, "other", "ci", time.Hour))
+	expect(201, "POST", "/api/v2/remotes", remote, good)
+	expect(401, "PUT", "/api/v2/remotes/srv-oidc", `{"package_type":"generic"}`, "")
+	expect(401, "DELETE", "/api/v2/remotes/srv-oidc", "", "")
+	expect(401, "POST", "/api/v2/virtuals", virtual, "")
+	expect(201, "POST", "/api/v2/virtuals", virtual, good)
+	expect(401, "PUT", "/api/v2/virtuals/srv-oidc-v", virtual, "")
+	expect(401, "DELETE", "/api/v2/virtuals/srv-oidc-v", "", "")
+
+	expect(200, "GET", "/api/v2/remotes", "", "")
+	expect(200, "GET", "/api/v2/remotes/srv-oidc", "", "")
+	expect(200, "GET", "/api/v2/virtuals/srv-oidc-v", "", "")
+	expect(201, "PUT", "/api/v2/remotes/srv-oidc/files/a.bin", "payload", "")
+	expect(200, "GET", "/api/v2/remotes/srv-oidc/files/a.bin", "", "")
+	if got := do("DELETE", "/api/v2/remotes/srv-oidc/files/a.bin", "", ""); got >= 400 {
+		t.Errorf("delete file: status %d", got)
+	}
+	if got := do("POST", "/api/v2/probe", `{}`, ""); got == 401 {
+		t.Error("probe gated")
+	}
+	if got := do("GET", "/v2/", "", ""); got == 401 {
+		t.Error("docker /v2 gated")
+	}
+
+	expect(204, "DELETE", "/api/v2/virtuals/srv-oidc-v", "", good)
+	expect(204, "DELETE", "/api/v2/remotes/srv-oidc", "", good)
+}

internal/server/server.go

@@ -15,6 +15,7 @@ import (
 	tfregistry "git.unkin.net/unkin/artifactapi/internal/api/terraform"
 	v1 "git.unkin.net/unkin/artifactapi/internal/api/v1"
 	v2 "git.unkin.net/unkin/artifactapi/internal/api/v2"
+	"git.unkin.net/unkin/artifactapi/internal/auth"
 	"git.unkin.net/unkin/artifactapi/internal/cache"
 	"git.unkin.net/unkin/artifactapi/internal/config"
 	"git.unkin.net/unkin/artifactapi/internal/database"
@@ -186,10 +187,11 @@ func (s *Server) routes() chi.Router {
 	statsHandler := v2.NewStatsHandler(s.db)
 	eventsHandler := v2.NewEventsHandler()
 	probeHandler := v2.NewProbeHandler(s.engine, s.db)
+	writeAuth := auth.NewBearerOIDC(s.cfg.OIDCIssuer, s.cfg.OIDCAudiences)
 
 	r.Route("/api/v2", func(r chi.Router) {
-		r.Mount("/remotes", remotesHandler.Routes())
-		r.Mount("/virtuals", virtualsHandler.Routes())
+		r.Mount("/remotes", writeAuth.RequireWrites(remotesHandler.Routes()))
+		r.Mount("/virtuals", writeAuth.RequireWrites(virtualsHandler.Routes()))
 		r.Mount("/health", healthHandler.Routes())
 		r.Mount("/stats", statsHandler.Routes())
 		r.Mount("/events", eventsHandler.Routes())

internal/testsupport/oidc.go

@@ -0,0 +1,73 @@
+package testsupport
+
+import (
+	"crypto/rand"
+	"crypto/rsa"
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"time"
+
+	"github.com/go-jose/go-jose/v4"
+	"github.com/go-jose/go-jose/v4/jwt"
+)
+
+// OIDCIssuer is a minimal OIDC issuer serving discovery and JWKS, signing
+// RS256 tokens with a generated key.
+type OIDCIssuer struct {
+	*httptest.Server
+	key *rsa.PrivateKey
+}
+
+func NewOIDCIssuer() *OIDCIssuer {
+	key, err := rsa.GenerateKey(rand.Reader, 2048)
+	if err != nil {
+		panic(err)
+	}
+	iss := &OIDCIssuer{key: key}
+	mux := http.NewServeMux()
+	mux.HandleFunc("/.well-known/openid-configuration", func(w http.ResponseWriter, r *http.Request) {
+		_ = json.NewEncoder(w).Encode(map[string]any{
+			"issuer":                                iss.URL,
+			"jwks_uri":                              iss.URL + "/keys",
+			"id_token_signing_alg_values_supported": []string{"RS256"},
+		})
+	})
+	mux.HandleFunc("/keys", func(w http.ResponseWriter, r *http.Request) {
+		_ = json.NewEncoder(w).Encode(jose.JSONWebKeySet{Keys: []jose.JSONWebKey{
+			{Key: &key.PublicKey, KeyID: "k1", Algorithm: "RS256", Use: "sig"},
+		}})
+	})
+	iss.Server = httptest.NewServer(mux)
+	return iss
+}
+
+// Token signs a token for aud and sub. Pass a nil key to use the issuer's own;
+// expiry is relative to now.
+func (o *OIDCIssuer) Token(key *rsa.PrivateKey, aud, sub string, expiry time.Duration) string {
+	now := time.Now()
+	return o.Sign(key, jwt.Claims{
+		Issuer:   o.URL,
+		Subject:  sub,
+		Audience: jwt.Audience{aud},
+		IssuedAt: jwt.NewNumericDate(now.Add(-time.Minute)),
+		Expiry:   jwt.NewNumericDate(now.Add(expiry)),
+	})
+}
+
+// Sign signs arbitrary claims with RS256. Pass a nil key to use the issuer's own.
+func (o *OIDCIssuer) Sign(key *rsa.PrivateKey, claims jwt.Claims) string {
+	if key == nil {
+		key = o.key
+	}
+	sig, err := jose.NewSigner(jose.SigningKey{Algorithm: jose.RS256, Key: key},
+		(&jose.SignerOptions{}).WithType("JWT").WithHeader("kid", "k1"))
+	if err != nil {
+		panic(err)
+	}
+	tok, err := jwt.Signed(sig).Claims(claims).Serialize()
+	if err != nil {
+		panic(err)
+	}
+	return tok
+}

migrations/0002_github_sync_retry.sql

@@ -0,0 +1,9 @@
+-- Failed GitHub release scans retry with backoff instead of waiting out a full
+-- mutable_ttl: sync_failures counts consecutive failures, next_retry_at gates
+-- the next claim while a retry is pending.
+ALTER TABLE github_rpm_sync_state    ADD COLUMN IF NOT EXISTS sync_failures INT NOT NULL DEFAULT 0;
+ALTER TABLE github_rpm_sync_state    ADD COLUMN IF NOT EXISTS next_retry_at TIMESTAMPTZ;
+ALTER TABLE github_deb_sync_state    ADD COLUMN IF NOT EXISTS sync_failures INT NOT NULL DEFAULT 0;
+ALTER TABLE github_deb_sync_state    ADD COLUMN IF NOT EXISTS next_retry_at TIMESTAMPTZ;
+ALTER TABLE github_alpine_sync_state ADD COLUMN IF NOT EXISTS sync_failures INT NOT NULL DEFAULT 0;
+ALTER TABLE github_alpine_sync_state ADD COLUMN IF NOT EXISTS next_retry_at TIMESTAMPTZ;

migrations/0003_cargo_index.sql

@@ -0,0 +1,15 @@
+-- Local cargo registries: one sparse-index line per published crate version.
+-- line holds the index JSON minus yanked, which flips on yank/unyank.
+CREATE TABLE IF NOT EXISTS cargo_index (
+	id           BIGSERIAL PRIMARY KEY,
+	repo_name    TEXT NOT NULL,
+	file_path    TEXT NOT NULL,
+	name         TEXT NOT NULL,
+	version      TEXT NOT NULL,
+	line         TEXT NOT NULL,
+	yanked       BOOLEAN NOT NULL DEFAULT FALSE,
+	created_at   TIMESTAMPTZ DEFAULT NOW(),
+	UNIQUE(repo_name, file_path)
+);
+
+CREATE INDEX IF NOT EXISTS idx_cargo_index_repo_name ON cargo_index(repo_name, lower(name));

ui/src/components/UsageInstructions.tsx

@@ -229,6 +229,25 @@ go mod download`,
       ];
 
     case 'cargo':
+      if (isLocal) {
+        return [
+          {
+            title: 'Add the private registry (real sparse registry)',
+            language: 'toml',
+            code: `# $CARGO_HOME/config.toml
+[registries.${name}]
+index = "sparse+${url}/api/v1/local/${name}/"`,
+            note: 'cargo requires a token for publish/yank: set CARGO_REGISTRIES_' + name.toUpperCase().replace(/-/g, '_') + '_TOKEN to any value.',
+          },
+          {
+            title: 'Publish, depend on and yank crates',
+            language: 'bash',
+            code: `cargo publish --registry ${name}
+cargo add <crate> --registry ${name}
+cargo yank --version <version> --registry ${name}`,
+          },
+        ];
+      }
       return [
         {
           title: 'Point crates.io at this sparse registry',