Add S3-compatible storage backend

internal/app/backends_test.go

@@ -110,11 +110,9 @@ func TestBackendFactoryOpensSSHDestinationWithRegisteredOpener(t *testing.T) {
 func TestBackendFactoryRejectsUnsupportedSource(t *testing.T) {
 	factory := newBackendFactory()
 	_, err := factory.openSource(context.Background(), config.Backend{
-		Backend:  config.BackendS3,
-		Endpoint: "https://s3.example.com",
-		Bucket:   "reports",
+		Backend: "ftp",
 	})
-	if err == nil || !strings.Contains(err.Error(), "source backend s3 is not implemented for execution") {
+	if err == nil || !strings.Contains(err.Error(), "source backend ftp is not implemented for execution") {
 		t.Fatalf("openSource() error = %v, want not implemented", err)
 	}
 }
@@ -122,15 +120,85 @@ func TestBackendFactoryRejectsUnsupportedSource(t *testing.T) {
 func TestBackendFactoryRejectsUnsupportedDestination(t *testing.T) {
 	factory := newBackendFactory()
 	_, err := factory.openDestination(context.Background(), config.Destination{
-		Backend:  config.BackendS3,
-		Endpoint: "https://s3.example.com",
-		Bucket:   "reports",
+		Backend: "ftp",
 	})
-	if err == nil || !strings.Contains(err.Error(), "backend s3 is not implemented for execution") {
+	if err == nil || !strings.Contains(err.Error(), "backend ftp is not implemented for execution") {
 		t.Fatalf("openDestination() error = %v, want not implemented", err)
 	}
 }
 
+func TestBackendFactoryOpensS3DestinationWithRegisteredOpener(t *testing.T) {
+	factory := &backendFactory{
+		registry:    storage.NewRegistry(),
+		environment: config.NewEnvironment(nil, func(string) (string, bool) { return "", false }),
+	}
+	var got storage.OpenConfig
+	if err := factory.registry.Register(config.BackendS3, func(ctx context.Context, cfg storage.OpenConfig) (storage.Backend, error) {
+		got = cfg
+		return fake.New(), nil
+	}); err != nil {
+		t.Fatalf("Register() error = %v", err)
+	}
+	forcePathStyle := false
+	backend, err := factory.openDestination(context.Background(), config.Destination{
+		Backend:   config.BackendS3,
+		Endpoint:  "https://s3.example.com",
+		Bucket:    "reports",
+		Prefix:    "archive",
+		Region:    config.DefaultS3Region,
+		ForcePath: &forcePathStyle,
+	})
+	if err != nil {
+		t.Fatalf("openDestination() error = %v", err)
+	}
+	if backend == nil {
+		t.Fatal("openDestination() backend = nil")
+	}
+	assertOpenConfig(t, got, map[string]string{
+		s3EndpointKey:       "https://s3.example.com",
+		s3BucketKey:         "reports",
+		s3PrefixKey:         "archive",
+		s3RegionKey:         config.DefaultS3Region,
+		s3ForcePathStyleKey: "false",
+	})
+}
+
+func TestBackendFactoryResolvesS3CredentialsThroughSecretsAwareEnvironment(t *testing.T) {
+	factory := &backendFactory{
+		registry: storage.NewRegistry(),
+		environment: config.NewEnvironment(map[string]string{
+			"ACCESS_KEY_ID":     "secret-access",
+			"SECRET_ACCESS_KEY": "secret-secret",
+		}, func(string) (string, bool) { return "", false }),
+	}
+	var got storage.OpenConfig
+	if err := factory.registry.Register(config.BackendS3, func(ctx context.Context, cfg storage.OpenConfig) (storage.Backend, error) {
+		got = cfg
+		return fake.New(), nil
+	}); err != nil {
+		t.Fatalf("Register() error = %v", err)
+	}
+	forcePathStyle := true
+	_, err := factory.openSource(context.Background(), config.Backend{
+		Backend:   config.BackendS3,
+		Endpoint:  "https://s3.example.com",
+		Bucket:    "reports",
+		Region:    config.DefaultS3Region,
+		ForcePath: &forcePathStyle,
+		Creds: config.Credentials{
+			AccessKeyIDEnv:     "ACCESS_KEY_ID",
+			SecretAccessKeyEnv: "SECRET_ACCESS_KEY",
+		},
+	})
+	if err != nil {
+		t.Fatalf("openSource() error = %v", err)
+	}
+	assertOpenConfig(t, got, map[string]string{
+		s3AccessKeyIDKey:  "secret-access",
+		s3SecretAccessKey: "secret-secret",
+	})
+}
+
 func TestBackendFactoryResolvesCredentialsThroughEnvironment(t *testing.T) {
 	factory := newBackendFactoryWithEnvironment(config.NewEnvironment(map[string]string{
 		"ACCESS_KEY_ID":     "secret-access",