Feat/v3 go rewrite (#47)

Complete rewrite of ArtifactAPI from Python/FastAPI to Go as a single binary.

Core engine:
- 10 package providers: generic, docker, helm, pypi, npm, rpm, alpine,
  puppet, terraform, goproxy — each with built-in mutable patterns
- Content-addressable storage (SHA256 dedup across all remotes)
- Three-tier caching: Redis (TTL/locks) → S3/MinIO (blobs) → upstream
- Classifier with allowlist/blocklist per-remote (empty = allow all)
- Circuit breaker, conditional revalidation, stale-on-error
- Background garbage collection for orphaned blobs
- Access logging to PostgreSQL

API:
- v1 proxy endpoints (backwards compatible)
- v2 management API: CRUD remotes/virtuals, object browser, stats,
  health, SSE events, probe/test endpoint
- Virtual repos with index merging (Helm YAML + PyPI HTML)

Frontend (React + Vite, separate Dockerfile):
- Dashboard with stats, health indicators, top remotes
- Remotes list with type filter, remote detail with config/patterns
- Object browser with pagination and evict
- Test Remote page: probe any remote path, see headers/size/timing
- Virtuals page with expandable member lists

TUI (Bubble Tea):
- Dashboard, remotes list/detail, object browser, virtuals
- Vim-style navigation, artifactapi tui --endpoint <url>

Infrastructure:
- S3 client supports MinIO, Ceph RGW, AWS S3 (minio-go)
- PostgreSQL schema with migrations
- Docker Compose: API + UI + Postgres 17 + Redis 7 + MinIO
- Makefile with Go version check, build/test/lint/fmt/e2e targets
- Distroless Docker image (~15MB)

Testing:
- Unit tests for models, classifier, providers, mergers
- E2E tests with testcontainers-go (real Postgres/Redis/MinIO)

Terraform config:
- All 40 production remotes + helm virtual as HCL
- Provider repo: terraform-provider-artifactapi v0.0.1 (separate)

---------

Co-authored-by: Ben Vincent <ben@unkin.net>
Reviewed-on: #47

internal/provider/alpine/alpine.go

@@ -0,0 +1,48 @@
+package alpine
+
+import (
+	"context"
+	"net/http"
+	"strings"
+
+	"git.unkin.net/unkin/artifactapi/internal/auth"
+	"git.unkin.net/unkin/artifactapi/internal/provider"
+	"git.unkin.net/unkin/artifactapi/pkg/models"
+)
+
+func init() {
+	provider.Register(&Provider{})
+}
+
+type Provider struct{}
+
+func (p *Provider) Type() models.PackageType { return models.PackageAlpine }
+
+func (p *Provider) Classify(path string) provider.Mutability {
+	if strings.HasSuffix(path, "APKINDEX.tar.gz") {
+		return provider.Mutable
+	}
+	return provider.Immutable
+}
+
+func (p *Provider) ContentType(path string) string {
+	if strings.HasSuffix(path, ".apk") {
+		return "application/vnd.android.package-archive"
+	}
+	if strings.HasSuffix(path, ".tar.gz") {
+		return "application/gzip"
+	}
+	return "application/octet-stream"
+}
+
+func (p *Provider) UpstreamURL(remote models.Remote, path string) string {
+	return strings.TrimRight(remote.BaseURL, "/") + "/" + strings.TrimLeft(path, "/")
+}
+
+func (p *Provider) RewriteResponse(_ []byte, _ models.Remote, _ string) ([]byte, error) {
+	return nil, nil
+}
+
+func (p *Provider) AuthHeaders(_ context.Context, remote models.Remote) (http.Header, error) {
+	return auth.BasicHeaders(remote), nil
+}

internal/provider/docker/docker.go

@@ -0,0 +1,62 @@
+package docker
+
+import (
+	"context"
+	"encoding/base64"
+	"net/http"
+	"regexp"
+	"strings"
+
+	"git.unkin.net/unkin/artifactapi/internal/provider"
+	"git.unkin.net/unkin/artifactapi/pkg/models"
+)
+
+func init() {
+	provider.Register(&Provider{})
+}
+
+var (
+	tagManifestRe    = regexp.MustCompile(`/manifests/[^/]+$`)
+	digestManifestRe = regexp.MustCompile(`/manifests/sha256:[0-9a-fA-F]+$`)
+	tagsListRe       = regexp.MustCompile(`/tags/list$`)
+)
+
+type Provider struct{}
+
+func (p *Provider) Type() models.PackageType { return models.PackageDocker }
+
+func (p *Provider) Classify(path string) provider.Mutability {
+	if tagsListRe.MatchString(path) {
+		return provider.Mutable
+	}
+	if tagManifestRe.MatchString(path) && !digestManifestRe.MatchString(path) {
+		return provider.Mutable
+	}
+	return provider.Immutable
+}
+
+func (p *Provider) ContentType(path string) string {
+	if strings.Contains(path, "/blobs/") {
+		return "application/octet-stream"
+	}
+	if strings.Contains(path, "/manifests/") {
+		return "application/vnd.docker.distribution.manifest.v2+json"
+	}
+	return "application/json"
+}
+
+func (p *Provider) UpstreamURL(remote models.Remote, path string) string {
+	return strings.TrimRight(remote.BaseURL, "/") + "/v2/" + strings.TrimLeft(path, "/")
+}
+
+func (p *Provider) RewriteResponse(_ []byte, _ models.Remote, _ string) ([]byte, error) {
+	return nil, nil
+}
+
+func (p *Provider) AuthHeaders(_ context.Context, remote models.Remote) (http.Header, error) {
+	h := http.Header{}
+	if remote.Username != "" && remote.Password != "" {
+		h.Set("Authorization", "Basic "+base64.StdEncoding.EncodeToString([]byte(remote.Username+":"+remote.Password)))
+	}
+	return h, nil
+}

internal/provider/docker/docker_test.go

@@ -0,0 +1,54 @@
+package docker_test
+
+import (
+	"testing"
+
+	"git.unkin.net/unkin/artifactapi/internal/provider"
+	"git.unkin.net/unkin/artifactapi/internal/provider/docker"
+	"git.unkin.net/unkin/artifactapi/pkg/models"
+)
+
+func TestProvider_Type(t *testing.T) {
+	p := &docker.Provider{}
+	if p.Type() != models.PackageDocker {
+		t.Errorf("expected docker, got %q", p.Type())
+	}
+}
+
+func TestProvider_Classify(t *testing.T) {
+	p := &docker.Provider{}
+	tests := []struct {
+		path string
+		want provider.Mutability
+	}{
+		{"library/nginx/manifests/latest", provider.Mutable},
+		{"library/nginx/manifests/v1.25", provider.Mutable},
+		{"library/nginx/manifests/sha256:abcdef1234567890abcdef1234567890abcdef1234567890abcdef1234567890", provider.Immutable},
+		{"library/nginx/tags/list", provider.Mutable},
+		{"library/nginx/blobs/sha256:abc123", provider.Immutable},
+	}
+	for _, tt := range tests {
+		if got := p.Classify(tt.path); got != tt.want {
+			t.Errorf("Classify(%q) = %v, want %v", tt.path, got, tt.want)
+		}
+	}
+}
+
+func TestProvider_UpstreamURL(t *testing.T) {
+	p := &docker.Provider{}
+	got := p.UpstreamURL(models.Remote{BaseURL: "https://registry-1.docker.io"}, "library/nginx/manifests/latest")
+	want := "https://registry-1.docker.io/v2/library/nginx/manifests/latest"
+	if got != want {
+		t.Errorf("got %q, want %q", got, want)
+	}
+}
+
+func TestProvider_ContentType(t *testing.T) {
+	p := &docker.Provider{}
+	if p.ContentType("x/blobs/sha256:abc") != "application/octet-stream" {
+		t.Error("blobs should be octet-stream")
+	}
+	if p.ContentType("x/manifests/latest") != "application/vnd.docker.distribution.manifest.v2+json" {
+		t.Error("manifests should be manifest type")
+	}
+}

internal/provider/generic/generic.go

@@ -0,0 +1,68 @@
+package generic
+
+import (
+	"context"
+	"encoding/base64"
+	"net/http"
+	"path"
+	"strings"
+
+	"git.unkin.net/unkin/artifactapi/internal/provider"
+	"git.unkin.net/unkin/artifactapi/pkg/models"
+)
+
+func init() {
+	provider.Register(&Provider{})
+}
+
+type Provider struct{}
+
+func (p *Provider) Type() models.PackageType { return models.PackageGeneric }
+
+func (p *Provider) Classify(_ string) provider.Mutability {
+	return provider.Immutable
+}
+
+var contentTypeMap = map[string]string{
+	".tar.gz": "application/gzip",
+	".tgz":    "application/gzip",
+	".gz":     "application/gzip",
+	".zip":    "application/zip",
+	".whl":    "application/zip",
+	".exe":    "application/x-msdownload",
+	".rpm":    "application/x-rpm",
+	".xml":    "application/xml",
+	".yaml":   "text/yaml",
+	".yml":    "text/yaml",
+	".json":   "application/json",
+	".sig":    "application/octet-stream",
+}
+
+func (p *Provider) ContentType(filePath string) string {
+	lower := strings.ToLower(filePath)
+	if strings.HasSuffix(lower, ".tar.gz") {
+		return "application/gzip"
+	}
+	ext := path.Ext(lower)
+	if ct, ok := contentTypeMap[ext]; ok {
+		return ct
+	}
+	return "application/octet-stream"
+}
+
+func (p *Provider) UpstreamURL(remote models.Remote, reqPath string) string {
+	base := strings.TrimRight(remote.BaseURL, "/")
+	return base + "/" + strings.TrimLeft(reqPath, "/")
+}
+
+func (p *Provider) RewriteResponse(_ []byte, _ models.Remote, _ string) ([]byte, error) {
+	return nil, nil
+}
+
+func (p *Provider) AuthHeaders(_ context.Context, remote models.Remote) (http.Header, error) {
+	h := http.Header{}
+	if remote.Username != "" {
+		h.Set("Authorization", "Basic "+base64.StdEncoding.EncodeToString([]byte(remote.Username+":"+remote.Password)))
+	}
+	return h, nil
+}

internal/provider/generic/generic_test.go

@@ -0,0 +1,69 @@
+package generic_test
+
+import (
+	"context"
+	"testing"
+
+	"git.unkin.net/unkin/artifactapi/internal/provider"
+	"git.unkin.net/unkin/artifactapi/internal/provider/generic"
+	"git.unkin.net/unkin/artifactapi/pkg/models"
+)
+
+func TestProvider_Type(t *testing.T) {
+	p := &generic.Provider{}
+	if p.Type() != models.PackageGeneric {
+		t.Errorf("expected generic, got %q", p.Type())
+	}
+}
+
+func TestProvider_Classify_AllImmutable(t *testing.T) {
+	p := &generic.Provider{}
+	paths := []string{"file.tar.gz", "path/to/binary", "index.html", "data.json"}
+	for _, path := range paths {
+		if p.Classify(path) != provider.Immutable {
+			t.Errorf("generic should classify %q as immutable", path)
+		}
+	}
+}
+
+func TestProvider_ContentType(t *testing.T) {
+	p := &generic.Provider{}
+	tests := []struct{ path, want string }{
+		{"file.tar.gz", "application/gzip"},
+		{"file.tgz", "application/gzip"},
+		{"file.zip", "application/zip"},
+		{"file.rpm", "application/x-rpm"},
+		{"file.json", "application/json"},
+		{"file.unknown", "application/octet-stream"},
+	}
+	for _, tt := range tests {
+		if got := p.ContentType(tt.path); got != tt.want {
+			t.Errorf("ContentType(%q) = %q, want %q", tt.path, got, tt.want)
+		}
+	}
+}
+
+func TestProvider_UpstreamURL(t *testing.T) {
+	p := &generic.Provider{}
+	got := p.UpstreamURL(models.Remote{BaseURL: "https://example.com/repo"}, "path/to/file.tar.gz")
+	want := "https://example.com/repo/path/to/file.tar.gz"
+	if got != want {
+		t.Errorf("got %q, want %q", got, want)
+	}
+}
+
+func TestProvider_AuthHeaders_BasicAuth(t *testing.T) {
+	p := &generic.Provider{}
+	h, _ := p.AuthHeaders(context.Background(), models.Remote{Username: "user", Password: "pass"})
+	if h.Get("Authorization") != "Basic dXNlcjpwYXNz" {
+		t.Errorf("unexpected auth header: %q", h.Get("Authorization"))
+	}
+}
+
+func TestProvider_AuthHeaders_NoAuth(t *testing.T) {
+	p := &generic.Provider{}
+	h, _ := p.AuthHeaders(context.Background(), models.Remote{})
+	if h.Get("Authorization") != "" {
+		t.Error("expected no auth header")
+	}
+}

internal/provider/goproxy/goproxy.go

@@ -0,0 +1,54 @@
+package goproxy
+
+import (
+	"context"
+	"net/http"
+	"strings"
+
+	"git.unkin.net/unkin/artifactapi/internal/auth"
+	"git.unkin.net/unkin/artifactapi/internal/provider"
+	"git.unkin.net/unkin/artifactapi/pkg/models"
+)
+
+func init() {
+	provider.Register(&Provider{})
+}
+
+type Provider struct{}
+
+func (p *Provider) Type() models.PackageType { return models.PackageGoProxy }
+
+func (p *Provider) Classify(path string) provider.Mutability {
+	if strings.HasSuffix(path, "/@v/list") || strings.HasSuffix(path, "/@latest") {
+		return provider.Mutable
+	}
+	return provider.Immutable
+}
+
+func (p *Provider) ContentType(path string) string {
+	if strings.HasSuffix(path, ".zip") {
+		return "application/zip"
+	}
+	if strings.HasSuffix(path, ".mod") {
+		return "text/plain"
+	}
+	if strings.HasSuffix(path, ".info") {
+		return "application/json"
+	}
+	if strings.HasSuffix(path, "/list") {
+		return "text/plain"
+	}
+	return "application/octet-stream"
+}
+
+func (p *Provider) UpstreamURL(remote models.Remote, path string) string {
+	return strings.TrimRight(remote.BaseURL, "/") + "/" + strings.TrimLeft(path, "/")
+}
+
+func (p *Provider) RewriteResponse(_ []byte, _ models.Remote, _ string) ([]byte, error) {
+	return nil, nil
+}
+
+func (p *Provider) AuthHeaders(_ context.Context, remote models.Remote) (http.Header, error) {
+	return auth.BasicHeaders(remote), nil
+}

internal/provider/goproxy/goproxy_test.go

@@ -0,0 +1,50 @@
+package goproxy_test
+
+import (
+	"testing"
+
+	"git.unkin.net/unkin/artifactapi/internal/provider"
+	"git.unkin.net/unkin/artifactapi/internal/provider/goproxy"
+	"git.unkin.net/unkin/artifactapi/pkg/models"
+)
+
+func TestProvider_Type(t *testing.T) {
+	p := &goproxy.Provider{}
+	if p.Type() != models.PackageGoProxy {
+		t.Errorf("expected goproxy, got %q", p.Type())
+	}
+}
+
+func TestProvider_Classify(t *testing.T) {
+	p := &goproxy.Provider{}
+	tests := []struct {
+		path string
+		want provider.Mutability
+	}{
+		{"golang.org/x/net/@v/list", provider.Mutable},
+		{"golang.org/x/net/@latest", provider.Mutable},
+		{"golang.org/x/net/@v/v0.1.0.info", provider.Immutable},
+		{"golang.org/x/net/@v/v0.1.0.mod", provider.Immutable},
+		{"golang.org/x/net/@v/v0.1.0.zip", provider.Immutable},
+	}
+	for _, tt := range tests {
+		if got := p.Classify(tt.path); got != tt.want {
+			t.Errorf("Classify(%q) = %v, want %v", tt.path, got, tt.want)
+		}
+	}
+}
+
+func TestProvider_ContentType(t *testing.T) {
+	p := &goproxy.Provider{}
+	tests := []struct{ path, want string }{
+		{"m/@v/v1.0.0.zip", "application/zip"},
+		{"m/@v/v1.0.0.mod", "text/plain"},
+		{"m/@v/v1.0.0.info", "application/json"},
+		{"m/@v/list", "text/plain"},
+	}
+	for _, tt := range tests {
+		if got := p.ContentType(tt.path); got != tt.want {
+			t.Errorf("ContentType(%q) = %q, want %q", tt.path, got, tt.want)
+		}
+	}
+}

internal/provider/helm/helm.go

@@ -0,0 +1,58 @@
+package helm
+
+import (
+	"context"
+	"net/http"
+	"strings"
+
+	"git.unkin.net/unkin/artifactapi/internal/auth"
+	"git.unkin.net/unkin/artifactapi/internal/provider"
+	"git.unkin.net/unkin/artifactapi/pkg/models"
+)
+
+func init() {
+	provider.Register(&Provider{})
+}
+
+type Provider struct{}
+
+func (p *Provider) Type() models.PackageType { return models.PackageHelm }
+
+func (p *Provider) Classify(path string) provider.Mutability {
+	if strings.HasSuffix(path, "index.yaml") || strings.HasSuffix(path, "index.yml") {
+		return provider.Mutable
+	}
+	return provider.Immutable
+}
+
+func (p *Provider) ContentType(path string) string {
+	if strings.HasSuffix(path, ".tgz") || strings.HasSuffix(path, ".tar.gz") {
+		return "application/gzip"
+	}
+	if strings.HasSuffix(path, ".yaml") || strings.HasSuffix(path, ".yml") {
+		return "text/yaml"
+	}
+	return "application/octet-stream"
+}
+
+func (p *Provider) UpstreamURL(remote models.Remote, path string) string {
+	return strings.TrimRight(remote.BaseURL, "/") + "/" + strings.TrimLeft(path, "/")
+}
+
+func (p *Provider) RewriteResponse(body []byte, remote models.Remote, proxyBaseURL string) ([]byte, error) {
+	if proxyBaseURL == "" {
+		return nil, nil
+	}
+	content := string(body)
+	baseURL := strings.TrimRight(remote.BaseURL, "/")
+	proxyURL := strings.TrimRight(proxyBaseURL, "/") + "/api/v1/remote/" + remote.Name
+	rewritten := strings.ReplaceAll(content, baseURL, proxyURL)
+	if rewritten == content {
+		return nil, nil
+	}
+	return []byte(rewritten), nil
+}
+
+func (p *Provider) AuthHeaders(_ context.Context, remote models.Remote) (http.Header, error) {
+	return auth.BasicHeaders(remote), nil
+}

internal/provider/helm/helm_test.go

@@ -0,0 +1,51 @@
+package helm_test
+
+import (
+	"strings"
+	"testing"
+
+	"git.unkin.net/unkin/artifactapi/internal/provider"
+	"git.unkin.net/unkin/artifactapi/internal/provider/helm"
+	"git.unkin.net/unkin/artifactapi/pkg/models"
+)
+
+func TestProvider_Type(t *testing.T) {
+	p := &helm.Provider{}
+	if p.Type() != models.PackageHelm {
+		t.Errorf("expected helm, got %q", p.Type())
+	}
+}
+
+func TestProvider_Classify(t *testing.T) {
+	p := &helm.Provider{}
+	tests := []struct {
+		path string
+		want provider.Mutability
+	}{
+		{"index.yaml", provider.Mutable},
+		{"index.yml", provider.Mutable},
+		{"chart-1.0.tgz", provider.Immutable},
+		{"charts/nginx-1.0.tgz", provider.Immutable},
+	}
+	for _, tt := range tests {
+		if got := p.Classify(tt.path); got != tt.want {
+			t.Errorf("Classify(%q) = %v, want %v", tt.path, got, tt.want)
+		}
+	}
+}
+
+func TestProvider_RewriteResponse(t *testing.T) {
+	p := &helm.Provider{}
+	body := []byte("urls:\n- https://charts.example.com/chart-1.0.tgz")
+	remote := models.Remote{Name: "helm-test", BaseURL: "https://charts.example.com"}
+	rewritten, err := p.RewriteResponse(body, remote, "https://proxy.example.com")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if rewritten == nil {
+		t.Fatal("expected rewrite")
+	}
+	if !strings.Contains(string(rewritten), "proxy.example.com/api/v1/remote/helm-test") {
+		t.Errorf("expected proxy URL in body: %s", rewritten)
+	}
+}

internal/provider/npm/npm.go

@@ -0,0 +1,56 @@
+package npm
+
+import (
+	"context"
+	"encoding/json"
+	"net/http"
+	"strings"
+
+	"git.unkin.net/unkin/artifactapi/internal/auth"
+	"git.unkin.net/unkin/artifactapi/internal/provider"
+	"git.unkin.net/unkin/artifactapi/pkg/models"
+)
+
+func init() {
+	provider.Register(&Provider{})
+}
+
+type Provider struct{}
+
+func (p *Provider) Type() models.PackageType { return models.PackageNPM }
+
+func (p *Provider) Classify(path string) provider.Mutability {
+	if strings.HasSuffix(path, ".tgz") {
+		return provider.Immutable
+	}
+	return provider.Mutable
+}
+
+func (p *Provider) ContentType(path string) string {
+	if strings.HasSuffix(path, ".tgz") {
+		return "application/gzip"
+	}
+	return "application/json"
+}
+
+func (p *Provider) UpstreamURL(remote models.Remote, path string) string {
+	return strings.TrimRight(remote.BaseURL, "/") + "/" + strings.TrimLeft(path, "/")
+}
+
+func (p *Provider) RewriteResponse(body []byte, remote models.Remote, proxyBaseURL string) ([]byte, error) {
+	if proxyBaseURL == "" || !json.Valid(body) {
+		return nil, nil
+	}
+	content := string(body)
+	baseURL := strings.TrimRight(remote.BaseURL, "/")
+	proxyURL := strings.TrimRight(proxyBaseURL, "/") + "/api/v1/remote/" + remote.Name
+	rewritten := strings.ReplaceAll(content, baseURL, proxyURL)
+	if rewritten == content {
+		return nil, nil
+	}
+	return []byte(rewritten), nil
+}
+
+func (p *Provider) AuthHeaders(_ context.Context, remote models.Remote) (http.Header, error) {
+	return auth.BasicHeaders(remote), nil
+}

internal/provider/provider.go

@@ -0,0 +1,52 @@
+package provider
+
+import (
+	"context"
+	"fmt"
+	"net/http"
+
+	"git.unkin.net/unkin/artifactapi/pkg/models"
+)
+
+type Mutability int
+
+const (
+	Immutable Mutability = iota
+	Mutable
+)
+
+type Provider interface {
+	Type() models.PackageType
+	Classify(path string) Mutability
+	ContentType(path string) string
+	UpstreamURL(remote models.Remote, path string) string
+	RewriteResponse(body []byte, remote models.Remote, proxyBaseURL string) ([]byte, error)
+	AuthHeaders(ctx context.Context, remote models.Remote) (http.Header, error)
+}
+
+type IndexMerger interface {
+	MergeIndexes(members []MemberIndex, proxyBaseURL string) ([]byte, error)
+}
+
+type MemberIndex struct {
+	RemoteName string
+	Body       []byte
+}
+
+var registry = map[models.PackageType]Provider{}
+
+func Register(p Provider) {
+	registry[p.Type()] = p
+}
+
+func Get(t models.PackageType) (Provider, error) {
+	p, ok := registry[t]
+	if !ok {
+		return nil, fmt.Errorf("no provider registered for package type %q", t)
+	}
+	return p, nil
+}
+
+func All() map[models.PackageType]Provider {
+	return registry
+}

internal/provider/puppet/puppet.go

@@ -0,0 +1,56 @@
+package puppet
+
+import (
+	"context"
+	"net/http"
+	"strings"
+
+	"git.unkin.net/unkin/artifactapi/internal/auth"
+	"git.unkin.net/unkin/artifactapi/internal/provider"
+	"git.unkin.net/unkin/artifactapi/pkg/models"
+)
+
+func init() {
+	provider.Register(&Provider{})
+}
+
+type Provider struct{}
+
+func (p *Provider) Type() models.PackageType { return models.PackagePuppet }
+
+func (p *Provider) Classify(path string) provider.Mutability {
+	if strings.HasPrefix(path, "v3/modules/") || strings.HasPrefix(path, "v3/releases") {
+		return provider.Mutable
+	}
+	return provider.Immutable
+}
+
+func (p *Provider) ContentType(path string) string {
+	if strings.HasSuffix(path, ".tar.gz") {
+		return "application/gzip"
+	}
+	if strings.HasPrefix(path, "v3/") {
+		return "application/json"
+	}
+	return "application/octet-stream"
+}
+
+func (p *Provider) UpstreamURL(remote models.Remote, path string) string {
+	return strings.TrimRight(remote.BaseURL, "/") + "/" + strings.TrimLeft(path, "/")
+}
+
+func (p *Provider) RewriteResponse(body []byte, remote models.Remote, proxyBaseURL string) ([]byte, error) {
+	if proxyBaseURL == "" {
+		return nil, nil
+	}
+	content := string(body)
+	proxyURL := strings.TrimRight(proxyBaseURL, "/") + "/api/v1/remote/" + remote.Name
+	content = strings.ReplaceAll(content, `"/v3/files/`, `"`+proxyURL+`/v3/files/`)
+	baseURL := strings.TrimRight(remote.BaseURL, "/")
+	content = strings.ReplaceAll(content, baseURL, proxyURL)
+	return []byte(content), nil
+}
+
+func (p *Provider) AuthHeaders(_ context.Context, remote models.Remote) (http.Header, error) {
+	return auth.BasicHeaders(remote), nil
+}

internal/provider/pypi/pypi.go

@@ -0,0 +1,62 @@
+package pypi
+
+import (
+	"context"
+	"net/http"
+	"strings"
+
+	"git.unkin.net/unkin/artifactapi/internal/auth"
+	"git.unkin.net/unkin/artifactapi/internal/provider"
+	"git.unkin.net/unkin/artifactapi/pkg/models"
+)
+
+func init() {
+	provider.Register(&Provider{})
+}
+
+type Provider struct{}
+
+func (p *Provider) Type() models.PackageType { return models.PackagePyPI }
+
+func (p *Provider) Classify(path string) provider.Mutability {
+	if strings.Contains(path, "simple/") {
+		return provider.Mutable
+	}
+	return provider.Immutable
+}
+
+func (p *Provider) ContentType(path string) string {
+	lower := strings.ToLower(path)
+	if strings.HasSuffix(lower, ".whl") || strings.HasSuffix(lower, ".zip") {
+		return "application/zip"
+	}
+	if strings.HasSuffix(lower, ".tar.gz") {
+		return "application/gzip"
+	}
+	if strings.Contains(path, "simple/") {
+		return "text/html"
+	}
+	return "application/octet-stream"
+}
+
+func (p *Provider) UpstreamURL(remote models.Remote, path string) string {
+	if strings.HasPrefix(path, "simple/") {
+		return "https://pypi.org/" + path
+	}
+	return strings.TrimRight(remote.BaseURL, "/") + "/" + strings.TrimLeft(path, "/")
+}
+
+func (p *Provider) RewriteResponse(body []byte, remote models.Remote, proxyBaseURL string) ([]byte, error) {
+	if proxyBaseURL == "" {
+		return nil, nil
+	}
+	content := string(body)
+	proxyURL := strings.TrimRight(proxyBaseURL, "/") + "/api/v1/remote/" + remote.Name + "/"
+	content = strings.ReplaceAll(content, "https://files.pythonhosted.org/", proxyURL)
+	content = strings.ReplaceAll(content, "../../", proxyURL)
+	return []byte(content), nil
+}
+
+func (p *Provider) AuthHeaders(_ context.Context, remote models.Remote) (http.Header, error) {
+	return auth.BasicHeaders(remote), nil
+}

internal/provider/rpm/rpm.go

@@ -0,0 +1,57 @@
+package rpm
+
+import (
+	"context"
+	"net/http"
+	"regexp"
+	"strings"
+
+	"git.unkin.net/unkin/artifactapi/internal/auth"
+	"git.unkin.net/unkin/artifactapi/internal/provider"
+	"git.unkin.net/unkin/artifactapi/pkg/models"
+)
+
+func init() {
+	provider.Register(&Provider{})
+}
+
+var mutableRe = []*regexp.Regexp{
+	regexp.MustCompile(`repomd\.xml$`),
+	regexp.MustCompile(`repodata/`),
+	regexp.MustCompile(`Packages\.gz$`),
+}
+
+type Provider struct{}
+
+func (p *Provider) Type() models.PackageType { return models.PackageRPM }
+
+func (p *Provider) Classify(path string) provider.Mutability {
+	for _, re := range mutableRe {
+		if re.MatchString(path) {
+			return provider.Mutable
+		}
+	}
+	return provider.Immutable
+}
+
+func (p *Provider) ContentType(path string) string {
+	if strings.HasSuffix(path, ".rpm") {
+		return "application/x-rpm"
+	}
+	if strings.HasSuffix(path, ".xml") || strings.HasSuffix(path, ".xml.gz") || strings.HasSuffix(path, ".xml.xz") {
+		return "application/xml"
+	}
+	return "application/octet-stream"
+}
+
+func (p *Provider) UpstreamURL(remote models.Remote, path string) string {
+	return strings.TrimRight(remote.BaseURL, "/") + "/" + strings.TrimLeft(path, "/")
+}
+
+func (p *Provider) RewriteResponse(_ []byte, _ models.Remote, _ string) ([]byte, error) {
+	return nil, nil
+}
+
+func (p *Provider) AuthHeaders(_ context.Context, remote models.Remote) (http.Header, error) {
+	return auth.BasicHeaders(remote), nil
+}

internal/provider/rpm/rpm_test.go

@@ -0,0 +1,35 @@
+package rpm_test
+
+import (
+	"testing"
+
+	"git.unkin.net/unkin/artifactapi/internal/provider"
+	"git.unkin.net/unkin/artifactapi/internal/provider/rpm"
+	"git.unkin.net/unkin/artifactapi/pkg/models"
+)
+
+func TestProvider_Type(t *testing.T) {
+	p := &rpm.Provider{}
+	if p.Type() != models.PackageRPM {
+		t.Errorf("expected rpm, got %q", p.Type())
+	}
+}
+
+func TestProvider_Classify(t *testing.T) {
+	p := &rpm.Provider{}
+	tests := []struct {
+		path string
+		want provider.Mutability
+	}{
+		{"repomd.xml", provider.Mutable},
+		{"repodata/primary.xml.gz", provider.Mutable},
+		{"Packages.gz", provider.Mutable},
+		{"package-1.0.rpm", provider.Immutable},
+		{"RPM-GPG-KEY-almalinux", provider.Immutable},
+	}
+	for _, tt := range tests {
+		if got := p.Classify(tt.path); got != tt.want {
+			t.Errorf("Classify(%q) = %v, want %v", tt.path, got, tt.want)
+		}
+	}
+}

internal/provider/terraform/terraform.go

@@ -0,0 +1,88 @@
+package terraform
+
+import (
+	"context"
+	"encoding/json"
+	"net/http"
+	"net/url"
+	"regexp"
+	"strings"
+
+	"git.unkin.net/unkin/artifactapi/internal/auth"
+	"git.unkin.net/unkin/artifactapi/internal/provider"
+	"git.unkin.net/unkin/artifactapi/pkg/models"
+)
+
+func init() {
+	provider.Register(&Provider{})
+}
+
+var versionsRe = regexp.MustCompile(`[^/]+/[^/]+/versions$`)
+
+type Provider struct{}
+
+func (p *Provider) Type() models.PackageType { return models.PackageTerraform }
+
+func (p *Provider) Classify(path string) provider.Mutability {
+	if versionsRe.MatchString(path) {
+		return provider.Mutable
+	}
+	return provider.Immutable
+}
+
+func (p *Provider) ContentType(path string) string {
+	lower := strings.ToLower(path)
+	if strings.HasSuffix(lower, ".zip") {
+		return "application/zip"
+	}
+	if strings.HasSuffix(lower, ".sig") {
+		return "application/octet-stream"
+	}
+	return "application/json"
+}
+
+func (p *Provider) UpstreamURL(remote models.Remote, path string) string {
+	return strings.TrimRight(remote.BaseURL, "/") + "/v1/providers/" + strings.TrimLeft(path, "/")
+}
+
+func (p *Provider) RewriteResponse(body []byte, remote models.Remote, proxyBaseURL string) ([]byte, error) {
+	if remote.ReleasesRemote == "" {
+		return nil, nil
+	}
+	if !json.Valid(body) {
+		return nil, nil
+	}
+
+	var data map[string]any
+	if err := json.Unmarshal(body, &data); err != nil {
+		return nil, nil
+	}
+
+	changed := false
+	for _, field := range []string{"download_url", "shasums_url", "shasums_signature_url"} {
+		if val, ok := data[field].(string); ok && val != "" {
+			rewritten := rewriteDownloadURL(val, remote.ReleasesRemote, proxyBaseURL)
+			if rewritten != val {
+				data[field] = rewritten
+				changed = true
+			}
+		}
+	}
+
+	if !changed {
+		return nil, nil
+	}
+	return json.Marshal(data)
+}
+
+func rewriteDownloadURL(originalURL, releasesRemote, proxyBaseURL string) string {
+	parsed, err := url.Parse(originalURL)
+	if err != nil || proxyBaseURL == "" {
+		return originalURL
+	}
+	return strings.TrimRight(proxyBaseURL, "/") + "/api/v1/remote/" + releasesRemote + parsed.Path
+}
+
+func (p *Provider) AuthHeaders(_ context.Context, remote models.Remote) (http.Header, error) {
+	return auth.BasicHeaders(remote), nil
+}

internal/provider/terraform/terraform_test.go

@@ -0,0 +1,55 @@
+package terraform_test
+
+import (
+	"encoding/json"
+	"strings"
+	"testing"
+
+	"git.unkin.net/unkin/artifactapi/internal/provider"
+	"git.unkin.net/unkin/artifactapi/internal/provider/terraform"
+	"git.unkin.net/unkin/artifactapi/pkg/models"
+)
+
+func TestProvider_Type(t *testing.T) {
+	p := &terraform.Provider{}
+	if p.Type() != models.PackageTerraform {
+		t.Errorf("expected terraform, got %q", p.Type())
+	}
+}
+
+func TestProvider_Classify(t *testing.T) {
+	p := &terraform.Provider{}
+	tests := []struct {
+		path string
+		want provider.Mutability
+	}{
+		{"hashicorp/vault/versions", provider.Mutable},
+		{"hashicorp/vault/0.28.0/download/linux/amd64", provider.Immutable},
+	}
+	for _, tt := range tests {
+		if got := p.Classify(tt.path); got != tt.want {
+			t.Errorf("Classify(%q) = %v, want %v", tt.path, got, tt.want)
+		}
+	}
+}
+
+func TestProvider_RewriteResponse_DownloadInfo(t *testing.T) {
+	p := &terraform.Provider{}
+	remote := models.Remote{Name: "tf", ReleasesRemote: "hashicorp-releases"}
+	body, _ := json.Marshal(map[string]any{
+		"download_url": "https://releases.hashicorp.com/terraform-provider-vault/0.28.0/file.zip",
+		"shasums_url":  "https://releases.hashicorp.com/terraform-provider-vault/0.28.0/SHA256SUMS",
+	})
+	rewritten, err := p.RewriteResponse(body, remote, "https://proxy")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if rewritten == nil {
+		t.Fatal("expected rewrite")
+	}
+	var result map[string]any
+	json.Unmarshal(rewritten, &result)
+	if !strings.Contains(result["download_url"].(string), "proxy/api/v1/remote/hashicorp-releases") {
+		t.Errorf("download_url not rewritten: %s", result["download_url"])
+	}
+}