Add Google Cloud Storage replica

cmd/litestream/main.go

@@ -20,6 +20,7 @@ import (
 
 	"github.com/benbjohnson/litestream"
 	"github.com/benbjohnson/litestream/file"
+	"github.com/benbjohnson/litestream/gcs"
 	"github.com/benbjohnson/litestream/s3"
 	_ "github.com/mattn/go-sqlite3"
 	"gopkg.in/yaml.v2"
@@ -330,6 +331,10 @@ func NewReplicaFromConfig(c *ReplicaConfig, db *litestream.DB) (_ *litestream.Re
 		if r.Client, err = newS3ReplicaClientFromConfig(c, r); err != nil {
 			return nil, err
 		}
+	case "gcs":
+		if r.Client, err = newGCSReplicaClientFromConfig(c, r); err != nil {
+			return nil, err
+		}
 	default:
 		return nil, fmt.Errorf("unknown replica type in config: %q", c.Type)
 	}
@@ -431,6 +436,45 @@ func newS3ReplicaClientFromConfig(c *ReplicaConfig, r *litestream.Replica) (_ *s
 	return client, nil
 }
 
+// newGCSReplicaClientFromConfig returns a new instance of gcs.ReplicaClient built from config.
+func newGCSReplicaClientFromConfig(c *ReplicaConfig, r *litestream.Replica) (_ *gcs.ReplicaClient, err error) {
+	// Ensure URL & constituent parts are not both specified.
+	if c.URL != "" && c.Path != "" {
+		return nil, fmt.Errorf("cannot specify url & path for gcs replica")
+	} else if c.URL != "" && c.Bucket != "" {
+		return nil, fmt.Errorf("cannot specify url & bucket for gcs replica")
+	}
+
+	bucket, path := c.Bucket, c.Path
+
+	// Apply settings from URL, if specified.
+	if c.URL != "" {
+		_, uhost, upath, err := ParseReplicaURL(c.URL)
+		if err != nil {
+			return nil, err
+		}
+
+		// Only apply URL parts to field that have not been overridden.
+		if path == "" {
+			path = upath
+		}
+		if bucket == "" {
+			bucket = uhost
+		}
+	}
+
+	// Ensure required settings are set.
+	if bucket == "" {
+		return nil, fmt.Errorf("bucket required for gcs replica")
+	}
+
+	// Build replica.
+	client := gcs.NewReplicaClient()
+	client.Bucket = bucket
+	client.Path = path
+	return client, nil
+}
+
 // applyLitestreamEnv copies "LITESTREAM" prefixed environment variables to
 // their AWS counterparts as the "AWS" prefix can be confusing when using a
 // non-AWS S3-compatible service.

cmd/litestream/main_test.go

@@ -8,6 +8,7 @@ import (
 
 	main "github.com/benbjohnson/litestream/cmd/litestream"
 	"github.com/benbjohnson/litestream/file"
+	"github.com/benbjohnson/litestream/gcs"
 	"github.com/benbjohnson/litestream/s3"
 )
 
@@ -160,23 +161,17 @@ func TestNewS3ReplicaFromConfig(t *testing.T) {
 			t.Fatalf("ForcePathStyle=%v, want %v", got, want)
 		}
 	})
-
-	t.Run("GCS", func(t *testing.T) {
-		r, err := main.NewReplicaFromConfig(&main.ReplicaConfig{URL: "s3://foo.storage.googleapis.com/bar"}, nil)
-		if err != nil {
-			t.Fatal(err)
-		} else if client, ok := r.Client.(*s3.ReplicaClient); !ok {
-			t.Fatal("unexpected replica type")
-		} else if got, want := client.Bucket, "foo"; got != want {
-			t.Fatalf("Bucket=%s, want %s", got, want)
-		} else if got, want := client.Path, "bar"; got != want {
-			t.Fatalf("Path=%s, want %s", got, want)
-		} else if got, want := client.Region, "us-east-1"; got != want {
-			t.Fatalf("Region=%s, want %s", got, want)
-		} else if got, want := client.Endpoint, "https://storage.googleapis.com"; got != want {
-			t.Fatalf("Endpoint=%s, want %s", got, want)
-		} else if got, want := client.ForcePathStyle, true; got != want {
-			t.Fatalf("ForcePathStyle=%v, want %v", got, want)
-		}
-	})
+}
+
+func TestNewGCSReplicaFromConfig(t *testing.T) {
+	r, err := main.NewReplicaFromConfig(&main.ReplicaConfig{URL: "gcs://foo/bar"}, nil)
+	if err != nil {
+		t.Fatal(err)
+	} else if client, ok := r.Client.(*gcs.ReplicaClient); !ok {
+		t.Fatal("unexpected replica type")
+	} else if got, want := client.Bucket, "foo"; got != want {
+		t.Fatalf("Bucket=%s, want %s", got, want)
+	} else if got, want := client.Path, "bar"; got != want {
+		t.Fatalf("Path=%s, want %s", got, want)
+	}
 }

cmd/litestream/replicate.go

@@ -12,6 +12,7 @@ import (
 
 	"github.com/benbjohnson/litestream"
 	"github.com/benbjohnson/litestream/file"
+	"github.com/benbjohnson/litestream/gcs"
 	"github.com/benbjohnson/litestream/s3"
 	"github.com/prometheus/client_golang/prometheus/promhttp"
 )
@@ -108,6 +109,8 @@ func (c *ReplicateCommand) Run(ctx context.Context) (err error) {
 				log.Printf("replicating to: name=%q type=%q path=%q", r.Name(), client.Type(), client.Path())
 			case *s3.ReplicaClient:
 				log.Printf("replicating to: name=%q type=%q bucket=%q path=%q region=%q endpoint=%q sync-interval=%s", r.Name(), client.Type(), client.Bucket, client.Path, client.Region, client.Endpoint, r.SyncInterval)
+			case *gcs.ReplicaClient:
+				log.Printf("replicating to: name=%q type=%q bucket=%q path=%q sync-interval=%s", r.Name(), client.Type(), client.Bucket, client.Path, r.SyncInterval)
 			default:
 				log.Printf("replicating to: name=%q type=%q", r.Name(), client.Type())
 			}