feat(http): add GCP authentication for ar+https scheme

go.mod

@@ -1,6 +1,6 @@
 module github.com/aptly-dev/aptly
 
-go 1.24
+go 1.24.0
 
 require (
 	github.com/AlekSi/pointer v1.1.0
@@ -41,6 +41,7 @@ require (
 )
 
 require (
+	cloud.google.com/go/compute/metadata v0.3.0 // indirect
 	github.com/Azure/azure-sdk-for-go/sdk/internal v1.10.0 // indirect
 	github.com/KyleBanks/depth v1.2.1 // indirect
 	github.com/PuerkitoBio/purell v1.1.1 // indirect
@@ -128,5 +129,6 @@ require (
 	github.com/swaggo/gin-swagger v1.6.0
 	github.com/swaggo/swag v1.16.3
 	go.etcd.io/etcd/client/v3 v3.5.15
+	golang.org/x/oauth2 v0.33.0
 	gopkg.in/yaml.v3 v3.0.1
 )

go.sum

@@ -1,3 +1,5 @@
+cloud.google.com/go/compute/metadata v0.3.0 h1:Tz+eQXMEqDIKRsmY3cHTL6FVaynIjX2QxYC4trgAKZc=
+cloud.google.com/go/compute/metadata v0.3.0/go.mod h1:zFmK7XCadkQkj6TtorcaGlCW1hT1fIilQDwofLpJ20k=
 github.com/AlekSi/pointer v1.1.0 h1:SSDMPcXD9jSl8FPy9cRzoRaMJtm9g9ggGTxecRUbQoI=
 github.com/AlekSi/pointer v1.1.0/go.mod h1:y7BvfRI3wXPWKXEBhU71nbnIEEZX0QTSB2Bj48UJIZE=
 github.com/Azure/azure-sdk-for-go/sdk/azcore v1.14.0 h1:nyQWyZvwGTvunIMxi1Y9uXkcyr+I7TeNrr/foo4Kpk8=
@@ -348,6 +350,8 @@ golang.org/x/net v0.7.0/go.mod h1:2Tu9+aMcznHK/AK1HMvgo6xiTLG5rD5rZLDS+rp2Bjs=
 golang.org/x/net v0.8.0/go.mod h1:QVkue5JL9kW//ek3r6jTKnTFis1tRmNAW2P1shuFdJc=
 golang.org/x/net v0.38.0 h1:vRMAPTMaeGqVhG5QyLJHqNDwecKTomGeqbnfZyKlBI8=
 golang.org/x/net v0.38.0/go.mod h1:ivrbrMbzFq5J41QOQh0siUuly180yBYtLp+CKbEaFx8=
+golang.org/x/oauth2 v0.33.0 h1:4Q+qn+E5z8gPRJfmRy7C2gGG3T4jIprK6aSYgTXGRpo=
+golang.org/x/oauth2 v0.33.0/go.mod h1:lzm5WQJQwKZ3nwavOZ3IS5Aulzxi68dUSgRHujetwEA=
 golang.org/x/sync v0.0.0-20180314180146-1d60e4601c6f/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.0.0-20190911185100-cd5d95a43a6e/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=

http/download.go

@@ -44,6 +44,7 @@ func NewDownloader(downLimit int64, maxTries int, progress aptly.Progress) aptly
 	transport.DisableCompression = true
 	initTransport(&transport)
 	transport.RegisterProtocol("ftp", &protocol.FTPRoundTripper{})
+	transport.RegisterProtocol("ar+https", NewGCPRoundTripper(&transport))
 
 	downloader := &downloaderImpl{
 		progress:  progress,

http/gcp_auth.go

@@ -0,0 +1,64 @@
+package http
+
+import (
+	"context"
+	"fmt"
+	"net/http"
+	"strings"
+	"sync"
+
+	"golang.org/x/oauth2"
+	"golang.org/x/oauth2/google"
+)
+
+// gcpRoundTripper wraps http.RoundTripper to add Google Cloud authentication.
+// It delays GCP authentication initialization until the first actual request is made.
+// This avoids unnecessary credential loading when ar+https protocol is not actually used.
+//
+// It uses Application Default Credentials (ADC) which checks:
+// 1. GOOGLE_APPLICATION_CREDENTIALS environment variable
+// 2. gcloud auth application-default credentials
+// 3. GCE/GKE metadata server
+// See https://cloud.google.com/docs/authentication/application-default-credentials for usage details.
+type gcpRoundTripper struct {
+	base     http.RoundTripper
+	initOnce sync.Once
+	tokenSrc oauth2.TokenSource
+	initErr  error
+}
+
+func (t *gcpRoundTripper) RoundTrip(req *http.Request) (*http.Response, error) {
+	// Lazy initialization: only initialize GCP credentials on first request
+	t.initOnce.Do(func() {
+		creds, err := google.FindDefaultCredentials(context.Background(),
+			"https://www.googleapis.com/auth/cloud-platform")
+		if err != nil {
+			t.initErr = fmt.Errorf("failed to find default credentials: %w", err)
+			return
+		}
+		t.tokenSrc = creds.TokenSource
+	})
+
+	reqCopy := req.Clone(req.Context())
+	reqCopy.URL.Scheme = strings.TrimPrefix(reqCopy.URL.Scheme, "ar+")
+
+	// Fall back to base transport if GCP auth initialization failed
+	if t.initErr != nil {
+		return t.base.RoundTrip(reqCopy)
+	}
+
+	token, err := t.tokenSrc.Token()
+	if err != nil {
+		return nil, fmt.Errorf("failed to get OAuth2 token: %w", err)
+	}
+	token.SetAuthHeader(reqCopy)
+
+	return t.base.RoundTrip(reqCopy)
+}
+
+// NewGCPRoundTripper creates a new RoundTripper that handles GCP authentication for ar+https protocol.
+func NewGCPRoundTripper(base http.RoundTripper) http.RoundTripper {
+	return &gcpRoundTripper{
+		base: base,
+	}
+}

http/gcp_auth_test.go

@@ -0,0 +1,110 @@
+package http
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"os"
+	"testing"
+
+	"golang.org/x/oauth2"
+)
+
+func TestGCPAuthTransport_RoundTrip(t *testing.T) {
+	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		auth := r.Header.Get("Authorization")
+		if auth == "" {
+			t.Error("Expected Authorization header, got none")
+		}
+		w.WriteHeader(http.StatusOK)
+	}))
+	defer ts.Close()
+
+	transport := NewGCPRoundTripper(http.DefaultTransport)
+
+	if os.Getenv("GOOGLE_APPLICATION_CREDENTIALS") == "" {
+		t.Skip("Skipping test: GOOGLE_APPLICATION_CREDENTIALS not set")
+	}
+
+	client := &http.Client{Transport: transport}
+	resp, err := client.Get(ts.URL)
+	if err != nil {
+		t.Fatalf("Failed to make request: %v", err)
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		t.Errorf("Expected status 200, got %d", resp.StatusCode)
+	}
+}
+
+func TestGCPAuthTransport_RoundTrip_with_dummy_tokenSource(t *testing.T) {
+	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		auth := r.Header.Get("Authorization")
+		if auth != "Bearer dummy-token" {
+			t.Errorf("Expected Authorization header 'Bearer dummy-token', got '%s'", auth)
+		}
+		w.WriteHeader(http.StatusOK)
+	}))
+	defer ts.Close()
+
+	// Use a dummy token source for testing
+	transport := &gcpRoundTripper{
+		base: http.DefaultTransport,
+		tokenSrc: oauth2.StaticTokenSource(&oauth2.Token{
+			AccessToken: "dummy-token",
+		}),
+	}
+	transport.initOnce.Do(func() {}) // Mark as initialized for testing
+
+	client := &http.Client{Transport: transport}
+	resp, err := client.Get(ts.URL)
+	if err != nil {
+		t.Fatalf("Failed to make request: %v", err)
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		t.Errorf("Expected status 200, got %d", resp.StatusCode)
+	}
+}
+
+func TestGCPAuthTransport_RoundTrip_with_InvalidCredentials(t *testing.T) {
+	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusForbidden)
+	}))
+	defer ts.Close()
+
+	// Create a temporary invalid credentials file
+	tmpFile, err := os.CreateTemp("", "invalid_credentials.json")
+	if err != nil {
+		t.Fatalf("Failed to create temp file: %s", err)
+	}
+	defer os.Remove(tmpFile.Name())
+	if _, err := tmpFile.WriteString(`{"invalid": "data"}`); err != nil {
+		t.Fatalf("Failed to write to temp file: %s", err)
+	}
+	tmpFile.Close()
+
+	defaultEnv := os.Getenv("GOOGLE_APPLICATION_CREDENTIALS")
+	os.Setenv("GOOGLE_APPLICATION_CREDENTIALS", tmpFile.Name())
+	defer os.Setenv("GOOGLE_APPLICATION_CREDENTIALS", defaultEnv)
+
+	transport := &gcpRoundTripper{
+		base: http.DefaultTransport,
+	}
+
+	client := &http.Client{Transport: transport}
+	resp, err := client.Get(ts.URL)
+	if err != nil {
+		t.Fatalf("Failed to make request: %s", err)
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusForbidden {
+		t.Errorf("Expected status 403, got %d", resp.StatusCode)
+	}
+
+	if transport.initErr == nil {
+		t.Error("Expected init error due to invalid credentials, got none")
+	}
+}