Gate local repo writes behind OIDC tokens

Add ARTIFACTAPI_AUTH_UPLOADS to require a verified token for local
uploads, deletes, evictions, /api/v1 publishes and /v2 push. Accept the
token as Bearer, Token, Basic password or bare header, and serve a
Docker registry token endpoint so pulls stay anonymous.

internal/config/env.go

@@ -61,6 +61,8 @@ type Config struct {
 	// Bearer-JWT auth on configuration writes; empty issuer disables it.
 	OIDCIssuer    string
 	OIDCAudiences []string
+	// AuthUploads extends that auth to local repo uploads, deletes and evictions.
+	AuthUploads bool
 }
 
 func (c *Config) DatabaseDSN() string {
@@ -105,6 +107,13 @@ func Load() (*Config, error) {
 	if oidcIssuer != "" && len(oidcAudiences) == 0 {
 		return nil, fmt.Errorf("ARTIFACTAPI_OIDC_AUDIENCE is required when ARTIFACTAPI_OIDC_ISSUER is set")
 	}
+	authUploads, err := strconv.ParseBool(getenv("ARTIFACTAPI_AUTH_UPLOADS", "false"))
+	if err != nil {
+		return nil, fmt.Errorf("invalid ARTIFACTAPI_AUTH_UPLOADS: %w", err)
+	}
+	if authUploads && oidcIssuer == "" {
+		return nil, fmt.Errorf("ARTIFACTAPI_OIDC_ISSUER is required when ARTIFACTAPI_AUTH_UPLOADS is set")
+	}
 
 	cfg := &Config{
 		ListenAddr: getenv("LISTEN_ADDR", ":8000"),
@@ -142,6 +151,7 @@ func Load() (*Config, error) {
 
 		OIDCIssuer:    oidcIssuer,
 		OIDCAudiences: oidcAudiences,
+		AuthUploads:   authUploads,
 	}
 
 	return cfg, nil

internal/config/env_test.go

@@ -81,3 +81,23 @@ func TestLoadOIDC(t *testing.T) {
 		t.Error("expected error for issuer without audience")
 	}
 }
+
+func TestLoadAuthUploads(t *testing.T) {
+	cfg, err := Load()
+	if err != nil || cfg.AuthUploads {
+		t.Fatalf("default: %v, AuthUploads=%v", err, cfg.AuthUploads)
+	}
+	t.Setenv("ARTIFACTAPI_AUTH_UPLOADS", "true")
+	if _, err := Load(); err == nil {
+		t.Error("expected error for AUTH_UPLOADS without issuer")
+	}
+	t.Setenv("ARTIFACTAPI_OIDC_ISSUER", "https://vault.example/v1/identity/oidc")
+	t.Setenv("ARTIFACTAPI_OIDC_AUDIENCE", "artifactapi")
+	if cfg, err := Load(); err != nil || !cfg.AuthUploads {
+		t.Fatalf("enabled: %v, AuthUploads=%v", err, cfg.AuthUploads)
+	}
+	t.Setenv("ARTIFACTAPI_AUTH_UPLOADS", "maybe")
+	if _, err := Load(); err == nil {
+		t.Error("expected error for invalid ARTIFACTAPI_AUTH_UPLOADS")
+	}
+}