GCS: Add service_account option (#6366)

* gcs client: add service_account support

* Update docs for GCS's service_account

* Fixed lint check failed

docs/sources/configuration/_index.md

@@ -864,6 +864,10 @@ The `gcs_storage_config` configures GCS as a general storage for different data
 # CLI flag: -<prefix>.gcs.bucketname
 [bucket_name: <string> | default = ""]
 
+# Service account key content in JSON format.
+# CLI flag: -<prefix>.gcs.service-account
+[service_account: <string> | default = ""]
+
 # The size of the buffer that GCS client for each PUT request. 0 to disable
 # buffering.
 # CLI flag: -<prefix>.gcs.chunk-buffer-size

pkg/storage/chunk/client/gcp/gcs_object_client.go

@@ -10,6 +10,7 @@ import (
 	"time"
 
 	"cloud.google.com/go/storage"
+	"github.com/grafana/dskit/flagext"
 	"github.com/pkg/errors"
 	"github.com/prometheus/client_golang/prometheus"
 	"google.golang.org/api/iterator"
@@ -33,6 +34,7 @@ type GCSObjectClient struct {
 // GCSConfig is config for the GCS Chunk Client.
 type GCSConfig struct {
 	BucketName       string         `yaml:"bucket_name"`
+	ServiceAccount   flagext.Secret `yaml:"service_account"`
 	ChunkBufferSize  int            `yaml:"chunk_buffer_size"`
 	RequestTimeout   time.Duration  `yaml:"request_timeout"`
 	EnableOpenCensus bool           `yaml:"enable_opencensus"`
@@ -49,6 +51,7 @@ func (cfg *GCSConfig) RegisterFlags(f *flag.FlagSet) {
 // RegisterFlagsWithPrefix registers flags with prefix.
 func (cfg *GCSConfig) RegisterFlagsWithPrefix(prefix string, f *flag.FlagSet) {
 	f.StringVar(&cfg.BucketName, prefix+"gcs.bucketname", "", "Name of GCS bucket. Please refer to https://cloud.google.com/docs/authentication/production for more information about how to configure authentication.")
+	f.Var(&cfg.ServiceAccount, prefix+"gcs.service-account", "Service account key content in JSON format, refer to https://cloud.google.com/iam/docs/creating-managing-service-account-keys for creation.")
 	f.IntVar(&cfg.ChunkBufferSize, prefix+"gcs.chunk-buffer-size", 0, "The size of the buffer that GCS client for each PUT request. 0 to disable buffering.")
 	f.DurationVar(&cfg.RequestTimeout, prefix+"gcs.request-timeout", 0, "The duration after which the requests to GCS should be timed out.")
 	f.BoolVar(&cfg.EnableOpenCensus, prefix+"gcs.enable-opencensus", true, "Enable OpenCensus (OC) instrumentation for all requests.")
@@ -81,7 +84,7 @@ func newGCSObjectClient(ctx context.Context, cfg GCSConfig, hedgingCfg hedging.C
 
 func newBucketHandle(ctx context.Context, cfg GCSConfig, hedgingCfg hedging.Config, enableHTTP2, hedging bool, clientFactory ClientFactory) (*storage.BucketHandle, error) {
 	var opts []option.ClientOption
-	transport, err := gcsTransport(ctx, storage.ScopeReadWrite, cfg.Insecure, enableHTTP2)
+	transport, err := gcsTransport(ctx, storage.ScopeReadWrite, cfg.Insecure, enableHTTP2, cfg.ServiceAccount)
 	if err != nil {
 		return nil, err
 	}
@@ -212,7 +215,7 @@ func (s *GCSObjectClient) IsObjectNotFoundErr(err error) bool {
 	return errors.Is(err, storage.ErrObjectNotExist)
 }
 
-func gcsTransport(ctx context.Context, scope string, insecure bool, http2 bool) (http.RoundTripper, error) {
+func gcsTransport(ctx context.Context, scope string, insecure bool, http2 bool, serviceAccount flagext.Secret) (http.RoundTripper, error) {
 	customTransport := &http.Transport{
 		Proxy: http.ProxyFromEnvironment,
 		DialContext: (&net.Dialer{
@@ -238,5 +241,8 @@ func gcsTransport(ctx context.Context, scope string, insecure bool, http2 bool)
 		// When using `insecure` (testing only), we add a fake API key as well to skip credential chain lookups.
 		transportOptions = append(transportOptions, option.WithAPIKey("insecure"))
 	}
+	if serviceAccount.String() != "" {
+		transportOptions = append(transportOptions, option.WithCredentialsJSON([]byte(serviceAccount.String())))
+	}
 	return google_http.NewTransport(ctx, customTransport, transportOptions...)
 }