feat: wire the circuit breaker into the proxy fetch path (#90)

Fixes #74

## Why
`internal/proxy/circuit.go` implemented and tested a circuit breaker, but nothing ever called it — a repeatedly-failing upstream was still hit on every request.

## Changes
- Construct a `CircuitBreaker` in `NewEngine`.
- In `Engine.Fetch`: short-circuit when the breaker is open (serve stale from the store if present, otherwise return 503), `RecordFailure` on each `UpstreamError`, and `RecordSuccess` on a successful fetch.

## Validation
- `go test ./internal/proxy/` and `make e2e` pass.

---------

Co-authored-by: BenVincent <benvin@main.unkin.net>
Reviewed-on: #90
Co-authored-by: Ben Vincent <ben@unkin.net>
Co-committed-by: Ben Vincent <ben@unkin.net>

.pre-commit-config.yaml

@@ -0,0 +1,24 @@
+repos:
+  - repo: https://github.com/pre-commit/pre-commit-hooks
+    rev: v5.0.0
+    hooks:
+      - id: trailing-whitespace
+      - id: end-of-file-fixer
+      - id: check-yaml
+      - id: check-added-large-files
+      - id: check-merge-conflict
+
+  - repo: https://github.com/dnephin/pre-commit-golang
+    rev: v0.5.1
+    hooks:
+      - id: go-fmt
+      - id: go-mod-tidy
+
+  - repo: local
+    hooks:
+      - id: go-vet
+        name: go vet
+        entry: go vet ./...
+        language: system
+        types: [go]
+        pass_filenames: false

.woodpecker/docker.yaml

@@ -8,6 +8,8 @@ steps:
     settings:
       registry: git.unkin.net
       repo: git.unkin.net/unkin/artifactapi
+      build_args:
+        VERSION: ${CI_COMMIT_TAG}
       username: droneci
       password:
         from_secret: DRONECI_PASSWORD
@@ -22,6 +24,8 @@ steps:
       repo: git.unkin.net/unkin/artifactapi-ui
       dockerfile: ui/Dockerfile.ui
       context: ui
+      build_args:
+        BASE_PATH: /ui
       username: droneci
       password:
         from_secret: DRONECI_PASSWORD

.woodpecker/pre-commit.yaml

@@ -3,7 +3,15 @@ when:
 
 steps:
   - name: pre-commit
-    image: golang:1.25
+    image: git.unkin.net/unkin/almalinux9-gobuilder:20260606
     commands:
-      - test -z "$(gofmt -l .)"
-      - go vet ./...
+      - uvx pre-commit run --all-files
+    backend_options:
+      kubernetes:
+        resources:
+          requests:
+            memory: 512Mi
+            cpu: 1
+          limits:
+            memory: 2Gi
+            cpu: 2

Dockerfile

@@ -9,7 +9,8 @@ RUN go mod download
 
 COPY . .
 
-RUN CGO_ENABLED=0 go build -ldflags="-s -w" -o artifactapi ./cmd/artifactapi
+ARG VERSION=dev
+RUN CGO_ENABLED=0 go build -ldflags="-s -w -X main.version=${VERSION}" -o artifactapi ./cmd/artifactapi
 
 FROM gcr.io/distroless/static-debian12:nonroot
 

Makefile

@@ -12,7 +12,7 @@ check-go:
 	fi
 
 build: check-go tidy
-	go build -ldflags="-s -w" -o $(BINARY) ./cmd/artifactapi
+	go build -ldflags="-s -w -X main.version=$(VERSION)" -o $(BINARY) ./cmd/artifactapi
 
 test: check-go
 	go test -race -count=1 ./pkg/... ./internal/...

cmd/artifactapi/main.go

@@ -13,6 +13,8 @@ import (
 	"git.unkin.net/unkin/artifactapi/internal/tui"
 )
 
+var version = "dev"
+
 func main() {
 	if len(os.Args) > 1 && os.Args[1] == "tui" {
 		endpoint := os.Getenv("ARTIFACTAPI_ENDPOINT")
@@ -42,7 +44,7 @@ func main() {
 	ctx, cancel := signal.NotifyContext(context.Background(), syscall.SIGINT, syscall.SIGTERM)
 	defer cancel()
 
-	srv, err := server.New(cfg)
+	srv, err := server.New(cfg, version)
 	if err != nil {
 		slog.Error("failed to create server", "error", err)
 		os.Exit(1)

e2e/e2e_test.go

@@ -95,7 +95,7 @@ func TestMain(m *testing.M) {
 	}
 	cfg.ListenAddr = "127.0.0.1:0"
 
-	srv, err := server.New(cfg)
+	srv, err := server.New(cfg, "e2e-test")
 	if err != nil {
 		log.Fatalf("server: %v", err)
 	}

e2e/management_test.go

@@ -24,6 +24,30 @@ func TestRoot(t *testing.T) {
 	}
 }
 
+func TestRemoteUpstreamTimeouts(t *testing.T) {
+	createRemote(t, `{
+		"name": "timeout-test",
+		"package_type": "generic",
+		"base_url": "https://example.com",
+		"stale_on_error": true,
+		"upstream_dial_timeout": 3,
+		"upstream_tls_timeout": 4,
+		"upstream_response_header_timeout": 5
+	}`)
+	defer deleteRemote(t, "timeout-test")
+
+	remote := getJSON(t, apiURL("/api/v2/remotes/timeout-test"))
+	for field, want := range map[string]float64{
+		"upstream_dial_timeout":            3,
+		"upstream_tls_timeout":             4,
+		"upstream_response_header_timeout": 5,
+	} {
+		if got, _ := remote[field].(float64); got != want {
+			t.Errorf("%s: got %v, want %v", field, remote[field], want)
+		}
+	}
+}
+
 func TestRemoteCRUD(t *testing.T) {
 	createRemote(t, `{
 		"name": "test-generic",

e2e/proxy_test.go

@@ -24,6 +24,39 @@ func TestProxyBlocklist(t *testing.T) {
 	assertStatus(t, apiURL("/api/v1/remote/blocklist-test/malware.exe"), http.StatusForbidden)
 }
 
+func TestProxyHeadBlocklist(t *testing.T) {
+	createRemote(t, `{
+		"name": "head-block-test",
+		"package_type": "generic",
+		"base_url": "https://example.com",
+		"blocklist": ["\\.exe$"],
+		"stale_on_error": true
+	}`)
+	defer deleteRemote(t, "head-block-test")
+
+	req, _ := http.NewRequest(http.MethodHead, apiURL("/v2/head-block-test/malware.exe"), nil)
+	resp, err := http.DefaultClient.Do(req)
+	if err != nil {
+		t.Fatalf("HEAD: %v", err)
+	}
+	resp.Body.Close()
+	if resp.StatusCode != http.StatusForbidden {
+		t.Fatalf("HEAD blocklisted path: got %d, want 403", resp.StatusCode)
+	}
+}
+
+func TestProxyHeadUnknownRemote(t *testing.T) {
+	req, _ := http.NewRequest(http.MethodHead, apiURL("/v2/nonexistent/some/path"), nil)
+	resp, err := http.DefaultClient.Do(req)
+	if err != nil {
+		t.Fatalf("HEAD: %v", err)
+	}
+	resp.Body.Close()
+	if resp.StatusCode != http.StatusNotFound {
+		t.Fatalf("HEAD unknown remote: got %d, want 404", resp.StatusCode)
+	}
+}
+
 func TestProxyPatterns(t *testing.T) {
 	createRemote(t, `{
 		"name": "patterns-test",

internal/api/v1/proxy.go

@@ -37,6 +37,20 @@ func (h *ProxyHandler) Routes() chi.Router {
 	return r
 }
 
+func (h *ProxyHandler) DockerV2Routes() chi.Router {
+	r := chi.NewRouter()
+	r.Get("/", h.handleDockerPing)
+	r.Head("/", h.handleDockerPing)
+	r.Get("/{remoteName}/*", h.handleProxy)
+	r.Head("/{remoteName}/*", h.handleProxyHead)
+	return r
+}
+
+func (h *ProxyHandler) handleDockerPing(w http.ResponseWriter, r *http.Request) {
+	w.Header().Set("Docker-Distribution-Api-Version", "registry/2.0")
+	w.WriteHeader(http.StatusOK)
+}
+
 func (h *ProxyHandler) handleProxy(w http.ResponseWriter, r *http.Request) {
 	remoteName := chi.URLParam(r, "remoteName")
 	path := chi.URLParam(r, "*")
@@ -53,7 +67,7 @@ func (h *ProxyHandler) handleProxy(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	result, err := h.engine.Fetch(r.Context(), *remote, path, prov)
+	result, err := h.engine.Fetch(r.Context(), *remote, path, prov, r.Header)
 	if err != nil {
 		var proxyErr *proxy.ProxyError
 		if errors.As(err, &proxyErr) {
@@ -75,6 +89,42 @@ func (h *ProxyHandler) handleProxy(w http.ResponseWriter, r *http.Request) {
 	io.Copy(w, result.Reader)
 }
 
+func (h *ProxyHandler) handleProxyHead(w http.ResponseWriter, r *http.Request) {
+	remoteName := chi.URLParam(r, "remoteName")
+	path := chi.URLParam(r, "*")
+
+	remote, err := h.db.GetRemote(r.Context(), remoteName)
+	if err != nil {
+		http.Error(w, fmt.Sprintf("remote %q not found", remoteName), http.StatusNotFound)
+		return
+	}
+
+	prov, err := provider.Get(remote.PackageType)
+	if err != nil {
+		http.Error(w, fmt.Sprintf("no provider for %q", remote.PackageType), http.StatusInternalServerError)
+		return
+	}
+
+	result, err := h.engine.Head(r.Context(), *remote, path, prov)
+	if err != nil {
+		var proxyErr *proxy.ProxyError
+		if errors.As(err, &proxyErr) {
+			http.Error(w, proxyErr.Message, proxyErr.Status)
+			return
+		}
+		slog.Error("proxy head failed", "remote", remoteName, "path", path, "error", err)
+		http.Error(w, "bad gateway", http.StatusBadGateway)
+		return
+	}
+
+	w.Header().Set("Content-Type", result.ContentType)
+	w.Header().Set("X-Artifact-Source", result.Source)
+	if result.Size > 0 {
+		w.Header().Set("Content-Length", fmt.Sprintf("%d", result.Size))
+	}
+	w.WriteHeader(http.StatusOK)
+}
+
 func (h *ProxyHandler) handleVirtual(w http.ResponseWriter, r *http.Request) {
 	virtualName := chi.URLParam(r, "virtualName")
 	path := chi.URLParam(r, "*")

internal/api/v2/remotes.go

@@ -69,6 +69,10 @@ func (h *RemotesHandler) create(w http.ResponseWriter, r *http.Request) {
 		http.Error(w, "base_url is required for remote repositories", http.StatusBadRequest)
 		return
 	}
+	if err := remote.ValidatePatterns(); err != nil {
+		http.Error(w, err.Error(), http.StatusBadRequest)
+		return
+	}
 	if err := h.db.CreateRemote(r.Context(), &remote); err != nil {
 		http.Error(w, err.Error(), http.StatusInternalServerError)
 		return
@@ -84,6 +88,10 @@ func (h *RemotesHandler) update(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 	remote.Name = name
+	if err := remote.ValidatePatterns(); err != nil {
+		http.Error(w, err.Error(), http.StatusBadRequest)
+		return
+	}
 	if err := h.db.UpdateRemote(r.Context(), &remote); err != nil {
 		http.Error(w, err.Error(), http.StatusInternalServerError)
 		return

internal/cache/redis.go

@@ -70,6 +70,18 @@ func (r *Redis) GetETag(ctx context.Context, remote, path string) (string, error
 	return val, err
 }
 
+func (r *Redis) GetToken(ctx context.Context, key string) (string, error) {
+	val, err := r.client.Get(ctx, "token:"+key).Result()
+	if err == redis.Nil {
+		return "", nil
+	}
+	return val, err
+}
+
+func (r *Redis) SetToken(ctx context.Context, key, token string, ttl time.Duration) error {
+	return r.client.Set(ctx, "token:"+key, token, ttl).Err()
+}
+
 func (r *Redis) IncrCircuitFailure(ctx context.Context, remote string, cooldown time.Duration) (int64, error) {
 	key := fmt.Sprintf("circuit:%s", remote)
 	pipe := r.client.Pipeline()

internal/config/env.go

@@ -65,7 +65,7 @@ func Load() (*Config, error) {
 }
 
 func getenv(key, fallback string) string {
-	if v := os.Getenv(key); v != "" {
+	if v, ok := os.LookupEnv(key); ok {
 		return v
 	}
 	return fallback

internal/database/artifacts.go

@@ -4,6 +4,8 @@ import (
 	"context"
 	"time"
 
+	"github.com/jackc/pgx/v5"
+
 	"git.unkin.net/unkin/artifactapi/pkg/models"
 )
 
@@ -109,16 +111,49 @@ func (db *DB) InsertAccessLog(ctx context.Context, remoteName, path string, cach
 	return err
 }
 
-func (db *DB) FindOrphanedBlobs(ctx context.Context) ([]models.Blob, error) {
+// AccessLogEntry is one buffered access-log record.
+type AccessLogEntry struct {
+	RemoteName string
+	Path       string
+	CacheHit   bool
+	SizeBytes  int64
+	UpstreamMS int
+	ClientIP   string
+}
+
+// InsertAccessLogBatch bulk-inserts access-log rows with a single COPY.
+func (db *DB) InsertAccessLogBatch(ctx context.Context, entries []AccessLogEntry) error {
+	if len(entries) == 0 {
+		return nil
+	}
+	rows := make([][]any, len(entries))
+	for i, e := range entries {
+		rows[i] = []any{e.RemoteName, e.Path, e.CacheHit, e.SizeBytes, e.UpstreamMS, e.ClientIP}
+	}
+	_, err := db.Pool.CopyFrom(ctx,
+		pgx.Identifier{"access_log"},
+		[]string{"remote_name", "path", "cache_hit", "size_bytes", "upstream_ms", "client_ip"},
+		pgx.CopyFromRows(rows),
+	)
+	return err
+}
+
+// FindOrphanedBlobs returns blobs no longer referenced by any artifact or
+// local file, restricted to those created before now()-minAge. The age cutoff
+// is a grace period that avoids a TOCTOU race with in-flight dedup uploads,
+// which insert the blob row before the referencing artifact/local_files row.
+func (db *DB) FindOrphanedBlobs(ctx context.Context, minAge time.Duration) ([]models.Blob, error) {
+	cutoff := time.Now().Add(-minAge)
 	rows, err := db.Pool.Query(ctx, `
 		SELECT b.content_hash, b.s3_key, b.size_bytes, b.content_type, b.created_at
 		FROM blobs b
-		WHERE b.content_hash NOT IN (
+		WHERE b.created_at < $1
+		  AND b.content_hash NOT IN (
 			SELECT content_hash FROM artifacts
 			UNION
 			SELECT content_hash FROM local_files
 		)
-	`)
+	`, cutoff)
 	if err != nil {
 		return nil, err
 	}

internal/database/postgres.go

@@ -124,6 +124,9 @@ func (db *DB) migrate() error {
 		CREATE INDEX IF NOT EXISTS idx_access_log_remote_time ON access_log(remote_name, created_at);
 
 		ALTER TABLE remotes ADD COLUMN IF NOT EXISTS repo_type TEXT DEFAULT 'remote';
+		ALTER TABLE remotes ADD COLUMN IF NOT EXISTS upstream_dial_timeout INTEGER DEFAULT 0;
+		ALTER TABLE remotes ADD COLUMN IF NOT EXISTS upstream_tls_timeout INTEGER DEFAULT 0;
+		ALTER TABLE remotes ADD COLUMN IF NOT EXISTS upstream_response_header_timeout INTEGER DEFAULT 0;
 
 		CREATE TABLE IF NOT EXISTS rpm_metadata (
 			id              BIGSERIAL PRIMARY KEY,

internal/database/remotes.go

@@ -11,7 +11,9 @@ const remoteCols = `name, package_type, repo_type, base_url, description, userna
 	patterns, blocklist, mutable_patterns, immutable_patterns,
 	ban_tags_enabled, ban_tags,
 	quarantine_enabled, quarantine_days, stale_on_error,
-	releases_remote, managed_by, created_at, updated_at`
+	releases_remote, managed_by,
+	upstream_dial_timeout, upstream_tls_timeout, upstream_response_header_timeout,
+	created_at, updated_at`
 
 func scanRemote(scanner interface{ Scan(...any) error }, r *models.Remote) error {
 	return scanner.Scan(
@@ -20,7 +22,9 @@ func scanRemote(scanner interface{ Scan(...any) error }, r *models.Remote) error
 		&r.Patterns, &r.Blocklist, &r.MutablePatterns, &r.ImmutablePatterns,
 		&r.BanTagsEnabled, &r.BanTags,
 		&r.QuarantineEnabled, &r.QuarantineDays, &r.StaleOnError,
-		&r.ReleasesRemote, &r.ManagedBy, &r.CreatedAt, &r.UpdatedAt,
+		&r.ReleasesRemote, &r.ManagedBy,
+		&r.UpstreamDialTimeout, &r.UpstreamTLSTimeout, &r.UpstreamResponseHeaderTimeout,
+		&r.CreatedAt, &r.UpdatedAt,
 	)
 }
 
@@ -59,8 +63,9 @@ func (db *DB) CreateRemote(ctx context.Context, r *models.Remote) error {
 			patterns, blocklist, mutable_patterns, immutable_patterns,
 			ban_tags_enabled, ban_tags,
 			quarantine_enabled, quarantine_days, stale_on_error,
-			releases_remote, managed_by
-		) VALUES ($1,$2,$3,$4,$5,$6,$7,$8,$9,$10,$11,$12,$13,$14,$15,$16,$17,$18,$19,$20,$21)
+			releases_remote, managed_by,
+			upstream_dial_timeout, upstream_tls_timeout, upstream_response_header_timeout
+		) VALUES ($1,$2,$3,$4,$5,$6,$7,$8,$9,$10,$11,$12,$13,$14,$15,$16,$17,$18,$19,$20,$21,$22,$23,$24)
 	`,
 		r.Name, r.PackageType, r.RepoType, r.BaseURL, r.Description, r.Username, r.Password,
 		r.ImmutableTTL, r.MutableTTL, r.CheckMutable,
@@ -68,6 +73,7 @@ func (db *DB) CreateRemote(ctx context.Context, r *models.Remote) error {
 		r.BanTagsEnabled, r.BanTags,
 		r.QuarantineEnabled, r.QuarantineDays, r.StaleOnError,
 		r.ReleasesRemote, r.ManagedBy,
+		r.UpstreamDialTimeout, r.UpstreamTLSTimeout, r.UpstreamResponseHeaderTimeout,
 	)
 	return err
 }
@@ -80,7 +86,9 @@ func (db *DB) UpdateRemote(ctx context.Context, r *models.Remote) error {
 			patterns=$11, blocklist=$12, mutable_patterns=$13, immutable_patterns=$14,
 			ban_tags_enabled=$15, ban_tags=$16,
 			quarantine_enabled=$17, quarantine_days=$18, stale_on_error=$19,
-			releases_remote=$20, managed_by=$21, updated_at=NOW()
+			releases_remote=$20, managed_by=$21,
+			upstream_dial_timeout=$22, upstream_tls_timeout=$23, upstream_response_header_timeout=$24,
+			updated_at=NOW()
 		WHERE name=$1
 	`,
 		r.Name, r.PackageType, r.RepoType, r.BaseURL, r.Description, r.Username, r.Password,
@@ -89,6 +97,7 @@ func (db *DB) UpdateRemote(ctx context.Context, r *models.Remote) error {
 		r.BanTagsEnabled, r.BanTags,
 		r.QuarantineEnabled, r.QuarantineDays, r.StaleOnError,
 		r.ReleasesRemote, r.ManagedBy,
+		r.UpstreamDialTimeout, r.UpstreamTLSTimeout, r.UpstreamResponseHeaderTimeout,
 	)
 	return err
 }

internal/database/rpm_metadata.go

@@ -33,29 +33,29 @@ func (db *DB) InsertRPMMetadata(ctx context.Context, meta *provider.RPMMetadata)
 }
 
 type RPMMetadataRow struct {
-	RepoName    string
-	FilePath    string
-	ContentHash string
-	Name        string
-	Epoch       int
-	Version     string
-	Release     string
-	Arch        string
-	Summary     string
-	Description string
-	RPMSize     int64
+	RepoName      string
+	FilePath      string
+	ContentHash   string
+	Name          string
+	Epoch         int
+	Version       string
+	Release       string
+	Arch          string
+	Summary       string
+	Description   string
+	RPMSize       int64
 	InstalledSize int64
-	License     string
-	Vendor      string
-	Group       string
-	BuildHost   string
-	SourceRPM   string
-	URL         string
-	Packager    string
-	Requires    json.RawMessage
-	Provides    json.RawMessage
-	Files       json.RawMessage
-	Changelogs  json.RawMessage
+	License       string
+	Vendor        string
+	Group         string
+	BuildHost     string
+	SourceRPM     string
+	URL           string
+	Packager      string
+	Requires      json.RawMessage
+	Provides      json.RawMessage
+	Files         json.RawMessage
+	Changelogs    json.RawMessage
 }
 
 func (db *DB) ListRPMMetadataEntries(ctx context.Context, repoName string) ([]provider.RPMMetadata, error) {

internal/database/stats.go

@@ -30,6 +30,15 @@ func (db *DB) GetOverviewStats(ctx context.Context) (*models.OverviewStats, erro
 		return nil, err
 	}
 
+	err = db.Pool.QueryRow(ctx, `
+		SELECT COALESCE(SUM(size_bytes), 0)
+		FROM access_log
+		WHERE cache_hit = TRUE AND created_at > NOW() - INTERVAL '30 days'
+	`).Scan(&stats.BandwidthSaved30d)
+	if err != nil {
+		return nil, err
+	}
+
 	return &stats, nil
 }
 

internal/gc/gc.go

@@ -9,6 +9,11 @@ import (
 	"git.unkin.net/unkin/artifactapi/internal/storage"
 )
 
+// blobGracePeriod is how old an orphaned blob must be before GC will delete
+// it. This avoids racing in-flight dedup uploads that insert the blob row
+// before the referencing artifact/local_files row exists.
+const blobGracePeriod = 1 * time.Hour
+
 type Collector struct {
 	db       *database.DB
 	store    *storage.S3
@@ -38,7 +43,7 @@ func (c *Collector) Run(ctx context.Context) {
 func (c *Collector) sweep(ctx context.Context) {
 	start := time.Now()
 
-	orphaned, err := c.db.FindOrphanedBlobs(ctx)
+	orphaned, err := c.db.FindOrphanedBlobs(ctx, blobGracePeriod)
 	if err != nil {
 		slog.Error("gc: find orphaned blobs", "error", err)
 		return

internal/proxy/classifier.go

@@ -2,6 +2,7 @@ package proxy
 
 import (
 	"regexp"
+	"sync"
 
 	"git.unkin.net/unkin/artifactapi/internal/provider"
 	"git.unkin.net/unkin/artifactapi/pkg/models"
@@ -60,10 +61,29 @@ func (c *Classifier) Classify(remote models.Remote, path string) Classification
 	return ClassImmutable
 }
 
+// patternCache memoises regex compilation. Classify runs on every proxied
+// request and previously recompiled each remote's pattern lists every time;
+// keying by the pattern string lets each distinct pattern compile once and
+// then be reused, with no invalidation needed (the pattern text is the key).
+// A pattern that fails to compile is cached as a typed nil so we don't retry.
+var patternCache sync.Map // map[string]*regexp.Regexp
+
+func compileCached(pattern string) *regexp.Regexp {
+	if v, ok := patternCache.Load(pattern); ok {
+		return v.(*regexp.Regexp)
+	}
+	re, err := regexp.Compile(pattern)
+	if err != nil {
+		re = nil
+	}
+	patternCache.Store(pattern, re)
+	return re
+}
+
 func compilePatterns(patterns []string) []*regexp.Regexp {
 	compiled := make([]*regexp.Regexp, 0, len(patterns))
 	for _, p := range patterns {
-		if re, err := regexp.Compile(p); err == nil {
+		if re := compileCached(p); re != nil {
 			compiled = append(compiled, re)
 		}
 	}

internal/proxy/engine.go

@@ -4,10 +4,13 @@ import (
 	"context"
 	"crypto/sha256"
 	"encoding/hex"
+	"encoding/json"
+	"errors"
 	"fmt"
 	"io"
 	"log/slog"
 	"net/http"
+	"strings"
 	"time"
 
 	"git.unkin.net/unkin/artifactapi/internal/cache"
@@ -19,19 +22,65 @@ import (
 
 const fetchLockTTL = 30 * time.Second
 
+const (
+	accessLogBufferSize = 4096
+	accessLogBatchSize  = 128
+	accessLogFlushEvery = 2 * time.Second
+)
+
 type Engine struct {
-	db    *database.DB
-	cache *cache.Redis
-	store *storage.S3
-	cas   *storage.CAS
+	db        *database.DB
+	cache     *cache.Redis
+	store     *storage.S3
+	cas       *storage.CAS
+	circuit   *CircuitBreaker
+	accessLog chan database.AccessLogEntry
 }
 
 func NewEngine(db *database.DB, c *cache.Redis, s *storage.S3) *Engine {
-	return &Engine{
-		db:    db,
-		cache: c,
-		store: s,
-		cas:   storage.NewCAS(s),
+	e := &Engine{
+		db:        db,
+		cache:     c,
+		store:     s,
+		cas:       storage.NewCAS(s),
+		circuit:   NewCircuitBreaker(c),
+		accessLog: make(chan database.AccessLogEntry, accessLogBufferSize),
+	}
+	go e.runAccessLogWriter()
+	return e
+}
+
+// runAccessLogWriter drains the access-log channel and writes rows in batches,
+// replacing a goroutine-per-request insert. It runs for the process lifetime;
+// access logs are best-effort telemetry, so a small tail may be lost on abrupt
+// shutdown.
+func (e *Engine) runAccessLogWriter() {
+	ticker := time.NewTicker(accessLogFlushEvery)
+	defer ticker.Stop()
+
+	batch := make([]database.AccessLogEntry, 0, accessLogBatchSize)
+	flush := func() {
+		if len(batch) == 0 {
+			return
+		}
+		ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+		if err := e.db.InsertAccessLogBatch(ctx, batch); err != nil {
+			slog.Warn("access log batch insert failed", "error", err, "count", len(batch))
+		}
+		cancel()
+		batch = batch[:0]
+	}
+
+	for {
+		select {
+		case entry := <-e.accessLog:
+			batch = append(batch, entry)
+			if len(batch) >= accessLogBatchSize {
+				flush()
+			}
+		case <-ticker.C:
+			flush()
+		}
 	}
 }
 
@@ -42,7 +91,7 @@ type FetchResult struct {
 	Source      string // "cache" or "remote"
 }
 
-func (e *Engine) Fetch(ctx context.Context, remote models.Remote, path string, prov provider.Provider) (*FetchResult, error) {
+func (e *Engine) Fetch(ctx context.Context, remote models.Remote, path string, prov provider.Provider, clientHeaders ...http.Header) (*FetchResult, error) {
 	classifier := NewClassifier(prov)
 	class := classifier.Classify(remote, path)
 
@@ -61,7 +110,7 @@ func (e *Engine) Fetch(ctx context.Context, remote models.Remote, path string, p
 		result, err := e.serveFromStore(ctx, remote, path)
 		if err == nil {
 			result.Source = "cache"
-			go e.logAccess(remote.Name, path, true, result.Size, 0)
+			e.logAccess(remote.Name, path, true, result.Size, 0)
 			return result, nil
 		}
 		slog.Warn("cache hit but S3 miss, re-fetching", "remote", remote.Name, "path", path)
@@ -73,11 +122,12 @@ func (e *Engine) Fetch(ctx context.Context, remote models.Remote, path string, p
 	}
 
 	if !locked {
-		time.Sleep(500 * time.Millisecond)
-		result, err := e.serveFromStore(ctx, remote, path)
-		if err == nil {
+		// Another request holds the fetch lock. Poll the store until the leader
+		// populates it rather than immediately racing to fetch upstream too; a
+		// cold-cache stampede otherwise hits upstream once per waiter.
+		if result := e.waitForStore(ctx, remote, path); result != nil {
 			result.Source = "cache"
-			go e.logAccess(remote.Name, path, true, result.Size, 0)
+			e.logAccess(remote.Name, path, true, result.Size, 0)
 			return result, nil
 		}
 	}
@@ -96,35 +146,138 @@ func (e *Engine) Fetch(ctx context.Context, remote models.Remote, path string, p
 				result, err := e.serveFromStore(ctx, remote, path)
 				if err == nil {
 					result.Source = "cache"
-					go e.logAccess(remote.Name, path, true, result.Size, 0)
+					e.logAccess(remote.Name, path, true, result.Size, 0)
 					return result, nil
 				}
 			}
 		}
 	}
 
+	var fwdHeaders http.Header
+	if len(clientHeaders) > 0 && clientHeaders[0] != nil {
+		fwdHeaders = clientHeaders[0]
+	}
+
+	// Short-circuit upstream calls when the remote's breaker is open: serve
+	// stale from the store if we have it, otherwise fail fast rather than
+	// hammering a known-bad upstream.
+	if e.circuit.IsOpen(ctx, remote.Name) {
+		if stale, serr := e.serveFromStore(ctx, remote, path); serr == nil {
+			slog.Warn("circuit open, serving stale", "remote", remote.Name, "path", path)
+			stale.Source = "cache"
+			e.logAccess(remote.Name, path, true, stale.Size, 0)
+			return stale, nil
+		}
+		return nil, &ProxyError{Status: http.StatusServiceUnavailable, Message: "upstream circuit open"}
+	}
+
 	start := time.Now()
-	result, err := e.fetchFromUpstream(ctx, remote, path, prov, class, ttl)
+	result, err := e.fetchFromUpstream(ctx, remote, path, prov, class, ttl, fwdHeaders)
 	upstreamMS := int(time.Since(start).Milliseconds())
 	if err != nil {
+		if isNetworkError(err) {
+			e.circuit.RecordFailure(ctx, remote.Name)
+		}
 		if remote.StaleOnError && isNetworkError(err) {
 			_ = e.cache.SetTTL(ctx, remote.Name, path, ttl)
 			stale, serr := e.serveFromStore(ctx, remote, path)
 			if serr == nil {
 				slog.Warn("serving stale on upstream error", "remote", remote.Name, "path", path, "error", err)
 				stale.Source = "cache"
-				go e.logAccess(remote.Name, path, true, stale.Size, 0)
+				e.logAccess(remote.Name, path, true, stale.Size, 0)
 				return stale, nil
 			}
 		}
 		return nil, err
 	}
 
-	go e.logAccess(remote.Name, path, false, result.Size, upstreamMS)
+	e.circuit.RecordSuccess(ctx, remote.Name)
+	e.logAccess(remote.Name, path, false, result.Size, upstreamMS)
 	return result, nil
 }
 
-func (e *Engine) fetchFromUpstream(ctx context.Context, remote models.Remote, path string, prov provider.Provider, class Classification, ttl time.Duration) (*FetchResult, error) {
+// HeadResult carries artifact metadata for a HEAD request. There is no body.
+type HeadResult struct {
+	ContentType string
+	Size        int64
+	Source      string // "cache" or "remote"
+}
+
+// Head resolves artifact metadata without fetching or streaming the body.
+// Cached artifacts/indexes are answered from the store metadata; on a miss it
+// issues an upstream HEAD. It never downloads or caches the body.
+func (e *Engine) Head(ctx context.Context, remote models.Remote, path string, prov provider.Provider) (*HeadResult, error) {
+	class := NewClassifier(prov).Classify(remote, path)
+	if class == ClassDenied {
+		return nil, &ProxyError{Status: http.StatusForbidden, Message: "access denied"}
+	}
+
+	if artifact, err := e.db.GetArtifact(ctx, remote.Name, path); err == nil && artifact != nil {
+		return &HeadResult{ContentType: artifact.ContentType, Size: artifact.SizeBytes, Source: "cache"}, nil
+	}
+	if info, err := e.store.Stat(ctx, storage.IndexKey(remote.Name, path)); err == nil {
+		return &HeadResult{ContentType: info.ContentType, Size: info.Size, Source: "cache"}, nil
+	}
+
+	return e.headUpstream(ctx, remote, path, prov)
+}
+
+func (e *Engine) headUpstream(ctx context.Context, remote models.Remote, path string, prov provider.Provider) (*HeadResult, error) {
+	url := prov.UpstreamURL(remote, path)
+
+	authHeaders, err := prov.AuthHeaders(ctx, remote)
+	if err != nil {
+		return nil, fmt.Errorf("auth headers: %w", err)
+	}
+
+	doHead := func(extra http.Header) (*http.Response, error) {
+		req, err := http.NewRequestWithContext(ctx, http.MethodHead, url, nil)
+		if err != nil {
+			return nil, fmt.Errorf("create request: %w", err)
+		}
+		for k, vv := range authHeaders {
+			for _, v := range vv {
+				req.Header.Add(k, v)
+			}
+		}
+		for k, vv := range extra {
+			for _, v := range vv {
+				req.Header.Set(k, v)
+			}
+		}
+		return http.DefaultClient.Do(req)
+	}
+
+	resp, err := doHead(nil)
+	if err != nil {
+		return nil, &UpstreamError{Err: err}
+	}
+	if resp.StatusCode == http.StatusUnauthorized {
+		resp.Body.Close()
+		token, _, terr := fetchBearerToken(ctx, resp.Header.Get("Www-Authenticate"), remote)
+		if terr == nil && token != "" {
+			resp, err = doHead(http.Header{"Authorization": []string{"Bearer " + token}})
+			if err != nil {
+				return nil, &UpstreamError{Err: err}
+			}
+		} else {
+			return nil, &ProxyError{Status: http.StatusUnauthorized, Message: "upstream returned 401"}
+		}
+	}
+	resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return nil, &ProxyError{Status: resp.StatusCode, Message: fmt.Sprintf("upstream returned %d", resp.StatusCode)}
+	}
+
+	contentType := prov.ContentType(path)
+	if ct := resp.Header.Get("Content-Type"); ct != "" {
+		contentType = ct
+	}
+	return &HeadResult{ContentType: contentType, Size: resp.ContentLength, Source: "remote"}, nil
+}
+
+func (e *Engine) fetchFromUpstream(ctx context.Context, remote models.Remote, path string, prov provider.Provider, class Classification, ttl time.Duration, clientHeaders http.Header) (*FetchResult, error) {
 	url := prov.UpstreamURL(remote, path)
 
 	authHeaders, err := prov.AuthHeaders(ctx, remote)
@@ -141,94 +294,144 @@ func (e *Engine) fetchFromUpstream(ctx context.Context, remote models.Remote, pa
 			req.Header.Add(k, v)
 		}
 	}
+	if clientHeaders != nil {
+		if accept := clientHeaders.Get("Accept"); accept != "" {
+			req.Header.Set("Accept", accept)
+		}
+	}
 
-	resp, err := http.DefaultClient.Do(req)
+	resp, err := clientForRemote(remote).Do(req)
 	if err != nil {
 		return nil, &UpstreamError{Err: err}
 	}
 
+	if resp.StatusCode == http.StatusUnauthorized {
+		resp.Body.Close()
+		token, err := e.cachedBearerToken(ctx, resp.Header.Get("Www-Authenticate"), remote)
+		if err == nil && token != "" {
+			req2, _ := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
+			req2.Header.Set("Authorization", "Bearer "+token)
+			if clientHeaders != nil {
+				if accept := clientHeaders.Get("Accept"); accept != "" {
+					req2.Header.Set("Accept", accept)
+				}
+			}
+			resp, err = clientForRemote(remote).Do(req2)
+			if err != nil {
+				return nil, &UpstreamError{Err: err}
+			}
+		} else {
+			return nil, &ProxyError{Status: http.StatusUnauthorized, Message: "upstream returned 401"}
+		}
+	}
+
 	if resp.StatusCode != http.StatusOK {
 		resp.Body.Close()
 		return nil, &ProxyError{Status: resp.StatusCode, Message: fmt.Sprintf("upstream returned %d", resp.StatusCode)}
 	}
 
-	body, err := io.ReadAll(resp.Body)
-	resp.Body.Close()
-	if err != nil {
-		return nil, fmt.Errorf("read upstream body: %w", err)
-	}
-
-	rewritten, err := prov.RewriteResponse(body, remote, "")
-	if err != nil {
-		return nil, fmt.Errorf("rewrite response: %w", err)
-	}
-	if rewritten != nil {
-		body = rewritten
-	}
-
 	contentType := prov.ContentType(path)
-	if ct := resp.Header.Get("Content-Type"); ct != "" && contentType == "application/octet-stream" {
+	if ct := resp.Header.Get("Content-Type"); ct != "" {
 		contentType = ct
 	}
 
+	// Mutable indexes are small and may be rewritten, so buffer them in memory.
 	if class == ClassMutable {
+		body, err := io.ReadAll(resp.Body)
+		resp.Body.Close()
+		if err != nil {
+			return nil, fmt.Errorf("read upstream body: %w", err)
+		}
+
+		rewritten, err := prov.RewriteResponse(body, remote, "")
+		if err != nil {
+			return nil, fmt.Errorf("rewrite response: %w", err)
+		}
+		if rewritten != nil {
+			body = rewritten
+		}
+
 		s3Key := storage.IndexKey(remote.Name, path)
 		if err := e.store.Upload(ctx, s3Key, bytesReader(body), int64(len(body)), contentType); err != nil {
 			return nil, fmt.Errorf("upload index: %w", err)
 		}
 
-		etag := resp.Header.Get("ETag")
-		_ = e.cache.SetTTL(ctx, remote.Name, path, ttl)
-		if etag != "" {
-			_ = e.cache.SetETag(ctx, remote.Name, path, etag, ttl)
-		}
-	} else {
-		hash := sha256Hash(body)
-		s3Key := storage.BlobKey(hash)
-
-		exists, _ := e.store.Exists(ctx, s3Key)
-		if !exists {
-			if err := e.store.Upload(ctx, s3Key, bytesReader(body), int64(len(body)), contentType); err != nil {
-				return nil, fmt.Errorf("upload blob: %w", err)
-			}
-		}
-
-		contentHash := fmt.Sprintf("sha256:%s", hash)
-		if err := e.db.UpsertBlob(ctx, contentHash, s3Key, int64(len(body)), contentType); err != nil {
-			slog.Warn("upsert blob failed", "error", err)
-		}
-		if err := e.db.UpsertArtifact(ctx, remote.Name, path, contentHash, resp.Header.Get("ETag")); err != nil {
-			slog.Warn("upsert artifact failed", "error", err)
-		}
-
 		_ = e.cache.SetTTL(ctx, remote.Name, path, ttl)
 		if etag := resp.Header.Get("ETag"); etag != "" {
 			_ = e.cache.SetETag(ctx, remote.Name, path, etag, ttl)
 		}
+
+		return &FetchResult{
+			Reader:      io.NopCloser(bytesReader(body)),
+			ContentType: contentType,
+			Size:        int64(len(body)),
+			Source:      "remote",
+		}, nil
 	}
 
+	// Immutable blobs are streamed through the content-addressable store
+	// (tempfile -> sha256 -> S3) so arbitrarily large artifacts never sit
+	// fully in memory. Immutable content is never rewritten in the proxy path.
+	casResult, err := e.cas.Store(ctx, resp.Body, contentType)
+	resp.Body.Close()
+	if err != nil {
+		return nil, fmt.Errorf("store blob: %w", err)
+	}
+
+	if err := e.db.UpsertBlob(ctx, casResult.ContentHash, casResult.S3Key, casResult.SizeBytes, contentType); err != nil {
+		slog.Warn("upsert blob failed", "error", err)
+	}
+	if err := e.db.UpsertArtifact(ctx, remote.Name, path, casResult.ContentHash, resp.Header.Get("ETag")); err != nil {
+		slog.Warn("upsert artifact failed", "error", err)
+	}
+
+	_ = e.cache.SetTTL(ctx, remote.Name, path, ttl)
+	if etag := resp.Header.Get("ETag"); etag != "" {
+		_ = e.cache.SetETag(ctx, remote.Name, path, etag, ttl)
+	}
+
+	reader, info, err := e.store.Download(ctx, casResult.S3Key)
+	if err != nil {
+		return nil, fmt.Errorf("serve stored blob: %w", err)
+	}
 	return &FetchResult{
-		Reader:      io.NopCloser(bytesReader(body)),
-		ContentType: contentType,
-		Size:        int64(len(body)),
+		Reader:      reader,
+		ContentType: info.ContentType,
+		Size:        casResult.SizeBytes,
 		Source:      "remote",
 	}, nil
 }
 
+// waitForStore polls the store for an artifact populated by the request that
+// holds the fetch lock, returning it once available or nil if it does not
+// appear within the wait budget (after which the caller fetches upstream
+// itself). It stops early if the request context is cancelled.
+func (e *Engine) waitForStore(ctx context.Context, remote models.Remote, path string) *FetchResult {
+	const (
+		pollInterval = 100 * time.Millisecond
+		maxWait      = 5 * time.Second
+	)
+	deadline := time.Now().Add(maxWait)
+	for {
+		if result, err := e.serveFromStore(ctx, remote, path); err == nil {
+			return result
+		}
+		if time.Now().After(deadline) {
+			return nil
+		}
+		select {
+		case <-ctx.Done():
+			return nil
+		case <-time.After(pollInterval):
+		}
+	}
+}
+
 func (e *Engine) serveFromStore(ctx context.Context, remote models.Remote, path string) (*FetchResult, error) {
 	artifact, err := e.db.GetArtifact(ctx, remote.Name, path)
 	if err == nil && artifact != nil {
-		reader, info, err := e.store.Download(ctx, artifact.ContentHash[len("sha256:"):])
-		if err == nil {
-			_ = e.db.TouchArtifactAccess(ctx, remote.Name, path)
-			return &FetchResult{
-				Reader:      reader,
-				ContentType: info.ContentType,
-				Size:        info.Size,
-			}, nil
-		}
 		s3Key := storage.BlobKey(artifact.ContentHash[len("sha256:"):])
-		reader, info, err = e.store.Download(ctx, s3Key)
+		reader, info, err := e.store.Download(ctx, s3Key)
 		if err == nil {
 			_ = e.db.TouchArtifactAccess(ctx, remote.Name, path)
 			return &FetchResult{
@@ -270,7 +473,7 @@ func (e *Engine) checkUpstream(ctx context.Context, remote models.Remote, path,
 		}
 	}
 
-	resp, err := http.DefaultClient.Do(req)
+	resp, err := clientForRemote(remote).Do(req)
 	if err != nil {
 		return false, &UpstreamError{Err: err}
 	}
@@ -291,15 +494,20 @@ func (e *Engine) ttlFor(remote models.Remote, class Classification) time.Duratio
 	}
 }
 
+// logAccess enqueues an access-log entry for the batch writer. It never blocks
+// the request path: if the buffer is full the entry is dropped.
 func (e *Engine) logAccess(remoteName, path string, cacheHit bool, size int64, upstreamMS int) {
-	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
-	defer cancel()
-	_ = e.db.InsertAccessLog(ctx, remoteName, path, cacheHit, size, upstreamMS, "")
-}
-
-func sha256Hash(data []byte) string {
-	h := sha256.Sum256(data)
-	return hex.EncodeToString(h[:])
+	select {
+	case e.accessLog <- database.AccessLogEntry{
+		RemoteName: remoteName,
+		Path:       path,
+		CacheHit:   cacheHit,
+		SizeBytes:  size,
+		UpstreamMS: upstreamMS,
+	}:
+	default:
+		slog.Warn("access log buffer full, dropping entry", "remote", remoteName, "path", path)
+	}
 }
 
 func bytesReader(data []byte) io.Reader {
@@ -319,6 +527,110 @@ func (r readerAt) ReadAt(p []byte, off int64) (n int, err error) {
 	return
 }
 
+// bearerTokenTTLDefault/Margin bound how long a token is cached: the default
+// is used when the token endpoint omits expires_in, and the margin is
+// subtracted so a cached token is refreshed slightly before it actually expires.
+const (
+	bearerTokenTTLDefault = 60 * time.Second
+	bearerTokenTTLMargin  = 10 * time.Second
+)
+
+func sha256Hash(data []byte) string {
+	h := sha256.Sum256(data)
+	return hex.EncodeToString(h[:])
+}
+
+// cachedBearerToken returns a bearer token for the given challenge, reusing a
+// Redis-cached token for the same remote+challenge while it is still valid.
+func (e *Engine) cachedBearerToken(ctx context.Context, wwwAuth string, remote models.Remote) (string, error) {
+	key := remote.Name + ":" + sha256Hash([]byte(wwwAuth))
+	if tok, err := e.cache.GetToken(ctx, key); err == nil && tok != "" {
+		return tok, nil
+	}
+
+	tok, ttl, err := fetchBearerToken(ctx, wwwAuth, remote)
+	if err != nil {
+		return "", err
+	}
+	if tok != "" {
+		if ttl <= 0 {
+			ttl = bearerTokenTTLDefault
+		}
+		if ttl > bearerTokenTTLMargin {
+			ttl -= bearerTokenTTLMargin
+		}
+		_ = e.cache.SetToken(ctx, key, tok, ttl)
+	}
+	return tok, nil
+}
+
+func fetchBearerToken(ctx context.Context, wwwAuth string, remote models.Remote) (string, time.Duration, error) {
+	if !strings.HasPrefix(wwwAuth, "Bearer ") {
+		return "", 0, fmt.Errorf("not a Bearer challenge")
+	}
+
+	params := map[string]string{}
+	for _, part := range strings.Split(wwwAuth[7:], ",") {
+		part = strings.TrimSpace(part)
+		eq := strings.Index(part, "=")
+		if eq < 0 {
+			continue
+		}
+		key := part[:eq]
+		val := strings.Trim(part[eq+1:], `"`)
+		params[key] = val
+	}
+
+	realm := params["realm"]
+	if realm == "" {
+		return "", 0, fmt.Errorf("no realm in Bearer challenge")
+	}
+
+	tokenURL := realm
+	sep := "?"
+	if s, ok := params["service"]; ok {
+		tokenURL += sep + "service=" + s
+		sep = "&"
+	}
+	if s, ok := params["scope"]; ok {
+		tokenURL += sep + "scope=" + s
+	}
+
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, tokenURL, nil)
+	if err != nil {
+		return "", 0, err
+	}
+
+	if remote.Username != "" && remote.Password != "" {
+		req.SetBasicAuth(remote.Username, remote.Password)
+	}
+
+	resp, err := clientForRemote(remote).Do(req)
+	if err != nil {
+		return "", 0, err
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return "", 0, fmt.Errorf("token endpoint returned %d", resp.StatusCode)
+	}
+
+	var tokenResp struct {
+		Token       string `json:"token"`
+		AccessToken string `json:"access_token"`
+		ExpiresIn   int    `json:"expires_in"`
+	}
+	if err := json.NewDecoder(resp.Body).Decode(&tokenResp); err != nil {
+		return "", 0, err
+	}
+
+	ttl := time.Duration(tokenResp.ExpiresIn) * time.Second
+	if tokenResp.Token != "" {
+		return tokenResp.Token, ttl, nil
+	}
+	return tokenResp.AccessToken, ttl, nil
+}
+
 type ProxyError struct {
 	Status  int
 	Message string
@@ -334,8 +646,6 @@ func (e *UpstreamError) Error() string { return fmt.Sprintf("upstream error: %v"
 func (e *UpstreamError) Unwrap() error { return e.Err }
 
 func isNetworkError(err error) bool {
-	if _, ok := err.(*UpstreamError); ok {
-		return true
-	}
-	return false
+	var ue *UpstreamError
+	return errors.As(err, &ue)
 }

internal/proxy/httpclient.go

@@ -0,0 +1,83 @@
+package proxy
+
+import (
+	"net"
+	"net/http"
+	"sync"
+	"time"
+
+	"git.unkin.net/unkin/artifactapi/pkg/models"
+)
+
+// Default upstream timeouts. A remote may override any of these; a zero
+// override falls back to the default here. There is deliberately no overall
+// Client.Timeout: the proxy streams arbitrarily large artifacts and total time
+// is bounded by the request context instead. We only constrain the phases that
+// must never hang — connect, TLS handshake, and time-to-first-response-header —
+// so a slow or wedged upstream cannot pin a goroutine and connection.
+const (
+	defaultDialTimeout           = 10 * time.Second
+	defaultTLSTimeout            = 10 * time.Second
+	defaultResponseHeaderTimeout = 30 * time.Second
+)
+
+type clientKey struct {
+	dial       time.Duration
+	tls        time.Duration
+	respHeader time.Duration
+}
+
+var (
+	clientCacheMu sync.Mutex
+	clientCache   = map[clientKey]*http.Client{}
+)
+
+// upstreamClientFor returns an HTTP client configured with the given timeouts,
+// reusing a cached client (and its connection pool) for identical timeout sets.
+// Zero values fall back to the defaults.
+func upstreamClientFor(dial, tls, respHeader time.Duration) *http.Client {
+	if dial <= 0 {
+		dial = defaultDialTimeout
+	}
+	if tls <= 0 {
+		tls = defaultTLSTimeout
+	}
+	if respHeader <= 0 {
+		respHeader = defaultResponseHeaderTimeout
+	}
+	key := clientKey{dial: dial, tls: tls, respHeader: respHeader}
+
+	clientCacheMu.Lock()
+	defer clientCacheMu.Unlock()
+	if c, ok := clientCache[key]; ok {
+		return c
+	}
+
+	c := &http.Client{
+		Transport: &http.Transport{
+			Proxy: http.ProxyFromEnvironment,
+			DialContext: (&net.Dialer{
+				Timeout:   dial,
+				KeepAlive: 30 * time.Second,
+			}).DialContext,
+			MaxIdleConns:          100,
+			MaxIdleConnsPerHost:   10,
+			IdleConnTimeout:       90 * time.Second,
+			TLSHandshakeTimeout:   tls,
+			ExpectContinueTimeout: 1 * time.Second,
+			ResponseHeaderTimeout: respHeader,
+		},
+	}
+	clientCache[key] = c
+	return c
+}
+
+// clientForRemote returns the upstream client for a remote, applying its
+// per-remote timeout overrides (in seconds) on top of the defaults.
+func clientForRemote(remote models.Remote) *http.Client {
+	return upstreamClientFor(
+		time.Duration(remote.UpstreamDialTimeout)*time.Second,
+		time.Duration(remote.UpstreamTLSTimeout)*time.Second,
+		time.Duration(remote.UpstreamResponseHeaderTimeout)*time.Second,
+	)
+}

internal/server/server.go

@@ -35,6 +35,7 @@ import (
 
 type Server struct {
 	cfg          *config.Config
+	version      string
 	router       chi.Router
 	db           *database.DB
 	cache        *cache.Redis
@@ -45,7 +46,7 @@ type Server struct {
 	gc           *gc.Collector
 }
 
-func New(cfg *config.Config) (*Server, error) {
+func New(cfg *config.Config, version string) (*Server, error) {
 	db, err := database.New(cfg.DatabaseDSN())
 	if err != nil {
 		return nil, fmt.Errorf("database: %w", err)
@@ -68,6 +69,7 @@ func New(cfg *config.Config) (*Server, error) {
 
 	s := &Server{
 		cfg:          cfg,
+		version:      version,
 		db:           db,
 		cache:        redis,
 		store:        s3,
@@ -96,6 +98,7 @@ func (s *Server) routes() chi.Router {
 
 	proxyHandler := v1.NewProxyHandler(s.engine, s.virtEngine, s.db, s.store, s.localHandler)
 	r.Mount("/api/v1", proxyHandler.Routes())
+	r.Mount("/v2", proxyHandler.DockerV2Routes())
 
 	remotesHandler := v2.NewRemotesHandler(s.db)
 	virtualsHandler := v2.NewVirtualsHandler(s.db)
@@ -137,7 +140,7 @@ func (s *Server) handleHealth(w http.ResponseWriter, r *http.Request) {
 func (s *Server) handleRoot(w http.ResponseWriter, r *http.Request) {
 	w.Header().Set("Content-Type", "application/json")
 	w.WriteHeader(http.StatusOK)
-	fmt.Fprint(w, `{"name":"artifactapi","version":"3.0.0-dev"}`)
+	fmt.Fprintf(w, `{"name":"artifactapi","version":"%s"}`, s.version)
 }
 
 func (s *Server) newHTTPServer() *http.Server {

internal/virtual/engine.go

@@ -79,7 +79,7 @@ func (e *Engine) fetchMemberIndexes(ctx context.Context, virt models.Virtual, pa
 					results[idx] = result{err: fmt.Errorf("local index %q: %w", name, err)}
 					return
 				}
-				results[idx] = result{index: MemberIndex{RemoteName: name, RepoType: remote.RepoType, Body: body}}
+				results[idx] = result{index: MemberIndex{RemoteName: name, RepoType: remote.RepoType, BaseURL: remote.BaseURL, Body: body}}
 				return
 			}
 
@@ -102,7 +102,7 @@ func (e *Engine) fetchMemberIndexes(ctx context.Context, virt models.Virtual, pa
 				return
 			}
 
-			results[idx] = result{index: MemberIndex{RemoteName: name, RepoType: remote.RepoType, Body: body}}
+			results[idx] = result{index: MemberIndex{RemoteName: name, RepoType: remote.RepoType, BaseURL: remote.BaseURL, Body: body}}
 		}(i, memberName)
 	}
 

internal/virtual/helm_merger.go

@@ -54,15 +54,27 @@ func (m *HelmMerger) MergeIndexes(members []MemberIndex, proxyBaseURL string) ([
 				seen[chart][ver.Version] = true
 
 				if proxyBaseURL != "" {
+					routePrefix := "remote"
+					if member.RepoType == "local" {
+						routePrefix = "local"
+					}
+					baseHost := extractHost(member.BaseURL)
+
 					for i, u := range ver.URLs {
 						if strings.HasPrefix(u, "http://") || strings.HasPrefix(u, "https://") {
-							ver.URLs[i] = fmt.Sprintf("%s/api/v1/remote/%s/%s",
+							if baseHost != "" && extractHost(u) != baseHost {
+								continue
+							}
+							relPath := extractPathRelativeToBase(u, member.BaseURL)
+							ver.URLs[i] = fmt.Sprintf("%s/api/v1/%s/%s/%s",
 								strings.TrimRight(proxyBaseURL, "/"),
+								routePrefix,
 								member.RemoteName,
-								extractPath(u))
+								relPath)
 						} else {
-							ver.URLs[i] = fmt.Sprintf("%s/api/v1/remote/%s/%s",
+							ver.URLs[i] = fmt.Sprintf("%s/api/v1/%s/%s/%s",
 								strings.TrimRight(proxyBaseURL, "/"),
+								routePrefix,
 								member.RemoteName,
 								u)
 						}
@@ -78,6 +90,31 @@ func (m *HelmMerger) MergeIndexes(members []MemberIndex, proxyBaseURL string) ([
 	return yaml.Marshal(merged)
 }
 
+func extractHost(rawURL string) string {
+	idx := strings.Index(rawURL, "://")
+	if idx == -1 {
+		return ""
+	}
+	rest := rawURL[idx+3:]
+	slashIdx := strings.Index(rest, "/")
+	if slashIdx == -1 {
+		return rest
+	}
+	return rest[:slashIdx]
+}
+
+func extractPathRelativeToBase(rawURL, baseURL string) string {
+	fullPath := extractPath(rawURL)
+	basePath := extractPath(baseURL)
+	if basePath != "" {
+		basePath = strings.TrimRight(basePath, "/") + "/"
+		if strings.HasPrefix(fullPath, basePath) {
+			return fullPath[len(basePath):]
+		}
+	}
+	return fullPath
+}
+
 func extractPath(rawURL string) string {
 	idx := strings.Index(rawURL, "://")
 	if idx == -1 {

internal/virtual/merger.go

@@ -9,6 +9,7 @@ import (
 type MemberIndex struct {
 	RemoteName string
 	RepoType   models.RepoType
+	BaseURL    string
 	Body       []byte
 }
 

pkg/models/remote.go

@@ -2,6 +2,7 @@ package models
 
 import (
 	"fmt"
+	"regexp"
 	"time"
 )
 
@@ -46,6 +47,11 @@ type Remote struct {
 	MutableTTL   int  `json:"mutable_ttl"`
 	CheckMutable bool `json:"check_mutable"`
 
+	// Upstream HTTP timeouts in seconds. 0 means use the server default.
+	UpstreamDialTimeout           int `json:"upstream_dial_timeout,omitempty"`
+	UpstreamTLSTimeout            int `json:"upstream_tls_timeout,omitempty"`
+	UpstreamResponseHeaderTimeout int `json:"upstream_response_header_timeout,omitempty"`
+
 	Patterns          []string `json:"patterns,omitempty"`
 	Blocklist         []string `json:"blocklist,omitempty"`
 	MutablePatterns   []string `json:"mutable_patterns,omitempty"`
@@ -66,6 +72,30 @@ type Remote struct {
 	UpdatedAt time.Time `json:"updated_at"`
 }
 
+// ValidatePatterns ensures every configured regex compiles. Storing an
+// invalid pattern would otherwise be silently dropped at match time, which
+// for the blocklist is a fail-open: a mistyped deny rule becomes a no-op.
+func (r *Remote) ValidatePatterns() error {
+	groups := []struct {
+		field    string
+		patterns []string
+	}{
+		{"patterns", r.Patterns},
+		{"blocklist", r.Blocklist},
+		{"mutable_patterns", r.MutablePatterns},
+		{"immutable_patterns", r.ImmutablePatterns},
+		{"ban_tags", r.BanTags},
+	}
+	for _, g := range groups {
+		for _, p := range g.patterns {
+			if _, err := regexp.Compile(p); err != nil {
+				return fmt.Errorf("invalid regex in %s: %q: %w", g.field, p, err)
+			}
+		}
+	}
+	return nil
+}
+
 type RemoteWithStats struct {
 	Remote
 	Stats RemoteStats `json:"stats"`

pkg/models/remote_test.go

@@ -0,0 +1,19 @@
+package models
+
+import "testing"
+
+func TestRemote_ValidatePatterns(t *testing.T) {
+	valid := &Remote{
+		Patterns:          []string{`.*\.tar\.gz$`},
+		Blocklist:         []string{`^secret/`},
+		ImmutablePatterns: []string{`\.rpm$`},
+	}
+	if err := valid.ValidatePatterns(); err != nil {
+		t.Fatalf("expected valid patterns, got %v", err)
+	}
+
+	bad := &Remote{Blocklist: []string{`[unterminated`}}
+	if err := bad.ValidatePatterns(); err == nil {
+		t.Fatal("expected error for invalid blocklist regex, got nil")
+	}
+}

ui/Dockerfile.ui

@@ -6,13 +6,20 @@ COPY package.json package-lock.json* ./
 RUN npm ci
 
 COPY . .
+
+ARG BASE_PATH=/
+ENV BASE_PATH=${BASE_PATH}
 RUN npm run build
 
 FROM nginx:alpine
 
+ARG BASE_PATH=/
+
 COPY --from=builder /app/dist /usr/share/nginx/html
 COPY nginx.conf /etc/nginx/conf.d/default.conf
 
+RUN sed -i "s|\${BASE_PATH}|${BASE_PATH}|g" /etc/nginx/conf.d/default.conf
+
 EXPOSE 80
 
 CMD ["nginx", "-g", "daemon off;"]

ui/nginx.conf

@@ -5,33 +5,12 @@ server {
     root /usr/share/nginx/html;
     index index.html;
 
-    location /api/ {
-        proxy_pass http://artifactapi:8000;
-        proxy_set_header Host $host;
-        proxy_set_header X-Real-IP $remote_addr;
-        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
-        proxy_set_header X-Forwarded-Proto $scheme;
-        proxy_buffering off;
-    }
-
-    location /v2/ {
-        proxy_pass http://artifactapi:8000;
-        proxy_set_header Host $host;
-        proxy_set_header X-Real-IP $remote_addr;
-        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
-        proxy_set_header X-Forwarded-Proto $scheme;
-        proxy_buffering off;
-    }
-
-    location /health {
-        proxy_pass http://artifactapi:8000;
-    }
-
-    location /metrics {
-        proxy_pass http://artifactapi:8000;
-    }
-
-    location / {
+    location ${BASE_PATH}/ {
+        rewrite ^${BASE_PATH}(/.*)$ $1 break;
         try_files $uri $uri/ /index.html;
     }
+
+    location = ${BASE_PATH} {
+        return 301 ${BASE_PATH}/;
+    }
 }

ui/src/App.tsx

@@ -2,6 +2,8 @@ import { Routes, Route, NavLink } from 'react-router-dom';
 import { Dashboard } from './pages/Dashboard';
 import { Remotes } from './pages/Remotes';
 import { RemoteDetail } from './pages/RemoteDetail';
+import { Locals } from './pages/Locals';
+import { LocalDetail } from './pages/LocalDetail';
 import { Virtuals } from './pages/Virtuals';
 import { Objects } from './pages/Objects';
 import { Probe } from './pages/Probe';
@@ -18,6 +20,7 @@ export function App() {
         <div className="sidebar-nav">
           <NavLink to="/" end>Dashboard</NavLink>
           <NavLink to="/remotes">Remotes</NavLink>
+          <NavLink to="/locals">Locals</NavLink>
           <NavLink to="/virtuals">Virtuals</NavLink>
           <NavLink to="/probe">Test Remote</NavLink>
         </div>
@@ -31,6 +34,9 @@ export function App() {
           <Route path="/remotes" element={<Remotes />} />
           <Route path="/remotes/:name" element={<RemoteDetail />} />
           <Route path="/remotes/:name/objects" element={<Objects />} />
+          <Route path="/locals" element={<Locals />} />
+          <Route path="/locals/:name" element={<LocalDetail />} />
+          <Route path="/locals/:name/objects" element={<Objects />} />
           <Route path="/virtuals" element={<Virtuals />} />
           <Route path="/probe" element={<Probe />} />
         </Routes>

ui/src/main.tsx

@@ -4,9 +4,13 @@ import { BrowserRouter } from 'react-router-dom';
 import { App } from './App';
 import './index.css';
 
+declare const __BASE_PATH__: string;
+
+const basename = __BASE_PATH__.replace(/\/+$/, '') || '/';
+
 createRoot(document.getElementById('root')!).render(
   <StrictMode>
-    <BrowserRouter>
+    <BrowserRouter basename={basename}>
       <App />
     </BrowserRouter>
   </StrictMode>,

ui/src/pages/Dashboard.tsx

@@ -50,6 +50,11 @@ export function Dashboard() {
           value={formatNumber(stats.total_blobs_deduped)}
           sub="shared blobs"
         />
+        <StatsCard
+          label="Bandwidth Saved"
+          value={formatBytes(stats.bandwidth_saved_30d)}
+          sub="last 30 days"
+        />
       </div>
 
       {health && (

ui/src/pages/LocalDetail.tsx

@@ -0,0 +1,46 @@
+import { useEffect, useState } from 'react';
+import { useParams, Link } from 'react-router-dom';
+import { api } from '../api/client';
+import type { Remote } from '../api/types';
+import { Badge } from '../components/Badge';
+import './RemoteDetail.css';
+
+export function LocalDetail() {
+  const { name } = useParams<{ name: string }>();
+  const [remote, setRemote] = useState<Remote | null>(null);
+  const [error, setError] = useState<string | null>(null);
+
+  useEffect(() => {
+    if (!name) return;
+    api.getRemote(name)
+      .then(setRemote)
+      .catch(e => setError(e.message));
+  }, [name]);
+
+  if (error) return <div className="error-banner">{error}</div>;
+  if (!remote) return <div className="loading">Loading...</div>;
+
+  return (
+    <div>
+      <div className="detail-header">
+        <Link to="/locals" className="back-link">&larr; Locals</Link>
+        <h1 className="page-title">{remote.name}</h1>
+        <div className="detail-badges">
+          <Badge variant="blue">{remote.package_type}</Badge>
+          <Badge variant="default">local</Badge>
+          {remote.managed_by && <Badge variant="green">managed by {remote.managed_by}</Badge>}
+        </div>
+      </div>
+
+      {remote.description && (
+        <p className="detail-description">{remote.description}</p>
+      )}
+
+      <div className="detail-actions">
+        <Link to={`/locals/${remote.name}/objects`} className="btn btn-primary">
+          Browse Files
+        </Link>
+      </div>
+    </div>
+  );
+}

ui/src/pages/Locals.tsx

@@ -0,0 +1,93 @@
+import { useEffect, useState } from 'react';
+import { useNavigate } from 'react-router-dom';
+import { api } from '../api/client';
+import type { Remote } from '../api/types';
+import { Badge } from '../components/Badge';
+import { DataTable } from '../components/DataTable';
+import './Remotes.css';
+
+const typeColors: Record<string, 'blue' | 'green' | 'yellow' | 'red' | 'default'> = {
+  docker: 'blue',
+  helm: 'green',
+  rpm: 'yellow',
+  pypi: 'blue',
+  npm: 'red',
+  generic: 'default',
+  alpine: 'green',
+  puppet: 'yellow',
+  terraform: 'blue',
+  goproxy: 'green',
+};
+
+export function Locals() {
+  const navigate = useNavigate();
+  const [remotes, setRemotes] = useState<Remote[]>([]);
+  const [filter, setFilter] = useState('');
+  const [loading, setLoading] = useState(true);
+
+  useEffect(() => {
+    api.listRemotes()
+      .then(r => setRemotes((r || []).filter(x => x.repo_type === 'local')))
+      .finally(() => setLoading(false));
+  }, []);
+
+  const filtered = remotes.filter(r => {
+    if (filter && !r.name.toLowerCase().includes(filter.toLowerCase())) return false;
+    return true;
+  });
+
+  return (
+    <div>
+      <h1 className="page-title">Local Repositories</h1>
+
+      <div className="remotes-toolbar">
+        <input
+          className="search-input"
+          placeholder="Filter by name..."
+          value={filter}
+          onChange={e => setFilter(e.target.value)}
+        />
+        <span className="result-count">{filtered.length} locals</span>
+      </div>
+
+      {loading ? (
+        <div className="loading">Loading...</div>
+      ) : (
+        <DataTable
+          columns={[
+            {
+              key: 'name',
+              header: 'Name',
+              render: (r: Remote) => <span className="mono">{r.name}</span>,
+            },
+            {
+              key: 'type',
+              header: 'Type',
+              render: (r: Remote) => (
+                <Badge variant={typeColors[r.package_type] || 'default'}>
+                  {r.package_type}
+                </Badge>
+              ),
+              width: '110px',
+            },
+            {
+              key: 'description',
+              header: 'Description',
+              render: (r: Remote) => r.description || <span className="text-muted">—</span>,
+            },
+            {
+              key: 'managed',
+              header: 'Managed',
+              render: (r: Remote) =>
+                r.managed_by ? <Badge variant="blue">{r.managed_by}</Badge> : <span className="text-muted">—</span>,
+              width: '100px',
+            },
+          ]}
+          data={filtered}
+          emptyMessage="No local repositories configured"
+          onRowClick={(r) => navigate(`/locals/${r.name}`)}
+        />
+      )}
+    </div>
+  );
+}

ui/src/pages/Objects.tsx

@@ -1,5 +1,5 @@
 import { useEffect, useState, useCallback, useMemo } from 'react';
-import { useParams, Link } from 'react-router-dom';
+import { useParams, useLocation, Link } from 'react-router-dom';
 import { api } from '../api/client';
 import type { Artifact } from '../api/types';
 import { formatBytes, timeAgo, truncateHash } from '../components/format';
@@ -171,6 +171,9 @@ function TreeRow({ node, depth, expanded, onToggle, onEvict }: TreeRowProps) {
 
 export function Objects() {
   const { name } = useParams<{ name: string }>();
+  const location = useLocation();
+  const isLocal = location.pathname.startsWith('/locals/');
+  const backLink = isLocal ? `/locals/${name}` : `/remotes/${name}`;
   const [artifacts, setArtifacts] = useState<Artifact[]>([]);
   const [loading, setLoading] = useState(true);
   const [filter, setFilter] = useState('');
@@ -233,7 +236,7 @@ export function Objects() {
   return (
     <div>
       <div className="detail-header">
-        <Link to={`/remotes/${name}`} className="back-link">&larr; {name}</Link>
+        <Link to={backLink} className="back-link">&larr; {name}</Link>
         <h1 className="page-title">Cached Objects</h1>
       </div>
 

ui/src/pages/Remotes.tsx

@@ -32,9 +32,10 @@ export function Remotes() {
       .finally(() => setLoading(false));
   }, []);
 
-  const types = [...new Set(remotes.map(r => r.package_type))].sort();
+  const remoteOnly = remotes.filter(r => r.repo_type !== 'local');
+  const types = [...new Set(remoteOnly.map(r => r.package_type))].sort();
 
-  const filtered = remotes.filter(r => {
+  const filtered = remoteOnly.filter(r => {
     if (typeFilter && r.package_type !== typeFilter) return false;
     if (filter && !r.name.toLowerCase().includes(filter.toLowerCase())) return false;
     return true;

ui/src/pages/Virtuals.tsx

@@ -1,21 +1,38 @@
 import { useEffect, useState } from 'react';
+import { Link } from 'react-router-dom';
 import { api } from '../api/client';
-import type { Virtual } from '../api/types';
+import type { Remote, Virtual } from '../api/types';
 import { Badge } from '../components/Badge';
 import { DataTable } from '../components/DataTable';
 import './Virtuals.css';
 
 export function Virtuals() {
   const [virtuals, setVirtuals] = useState<Virtual[]>([]);
+  const [remoteMap, setRemoteMap] = useState<Record<string, Remote>>({});
   const [loading, setLoading] = useState(true);
   const [expanded, setExpanded] = useState<string | null>(null);
 
   useEffect(() => {
-    api.listVirtuals()
-      .then(v => setVirtuals(v || []))
+    Promise.all([api.listVirtuals(), api.listRemotes()])
+      .then(([v, r]) => {
+        setVirtuals(v || []);
+        const map: Record<string, Remote> = {};
+        for (const remote of r || []) {
+          map[remote.name] = remote;
+        }
+        setRemoteMap(map);
+      })
       .finally(() => setLoading(false));
   }, []);
 
+  function memberLink(name: string) {
+    const remote = remoteMap[name];
+    if (remote?.repo_type === 'local') {
+      return `/locals/${name}`;
+    }
+    return `/remotes/${name}`;
+  }
+
   return (
     <div>
       <h1 className="page-title">Virtual Repositories</h1>
@@ -40,7 +57,7 @@ export function Virtuals() {
               key: 'members',
               header: 'Members',
               render: (v: Virtual) => (
-                <span className="member-count">{v.members?.length || 0} remotes</span>
+                <span className="member-count">{v.members?.length || 0} repos</span>
               ),
               width: '110px',
             },
@@ -69,12 +86,17 @@ export function Virtuals() {
           <ul className="member-list">
             {virtuals
               .find(v => v.name === expanded)
-              ?.members?.map((m, i) => (
-                <li key={m}>
-                  <span className="member-priority">{i + 1}</span>
-                  <a href={`/remotes/${m}`} className="mono">{m}</a>
-                </li>
-              ))}
+              ?.members?.map((m, i) => {
+                const remote = remoteMap[m];
+                const typeLabel = remote?.repo_type === 'local' ? 'local' : 'remote';
+                return (
+                  <li key={m}>
+                    <span className="member-priority">{i + 1}</span>
+                    <Link to={memberLink(m)} className="mono">{m}</Link>
+                    <Badge variant={typeLabel === 'local' ? 'yellow' : 'default'}>{typeLabel}</Badge>
+                  </li>
+                );
+              })}
           </ul>
         </div>
       )}

ui/vite.config.ts

@@ -1,7 +1,10 @@
 import { defineConfig } from 'vite'
 import react from '@vitejs/plugin-react'
 
+const basePath = process.env.BASE_PATH || '/'
+
 export default defineConfig({
+  base: basePath,
   plugins: [react()],
   server: {
     proxy: {
@@ -11,4 +14,7 @@ export default defineConfig({
       '/metrics': 'http://localhost:8000',
     },
   },
+  define: {
+    '__BASE_PATH__': JSON.stringify(basePath),
+  },
 })