gcs: add support for automatic credentials

We can now also support implicit credentials using the Application
Default Credentials strategy

README.md

@@ -587,7 +587,7 @@ Other notes:
 
 Each user can be mapped with a Google Cloud Storage bucket or a bucket virtual folder, this way the mapped bucket/virtual folder is exposed over SFTP/SCP. This backend is very similar to the S3 backend and it has the same limitations.
 
-To connect SFTPGo to Google Cloud Storage you need a credentials file that you can obtain from the Google Cloud Console, take a look at the "Setting up authentication" section [here](https://cloud.google.com/storage/docs/reference/libraries) for details.
+To connect SFTPGo to Google Cloud Storage you can use use the Application Default Credentials (ADC) strategy to try to find your application's credentials automatically or you can explicitly provide a JSON credentials file that you can obtain from the Google Cloud Console, take a look [here](https://cloud.google.com/docs/authentication/production#providing_credentials_to_your_application) for details.
 
 You can optionally specify a [storage class](https://cloud.google.com/storage/docs/storage-classes) too, leave blank to use the default storage class.
 
@@ -618,29 +618,30 @@ Usage:
   sftpgo portable [flags]
 
 Flags:
-  -C, --advertise-credentials         If the SFTP service is advertised via multicast DNS this flag allows to put username/password inside the advertised TXT record
+  -C, --advertise-credentials           If the SFTP service is advertised via multicast DNS this flag allows to put username/password inside the advertised TXT record
-  -S, --advertise-service             Advertise SFTP service using multicast DNS (default true)
+  -S, --advertise-service               Advertise SFTP service using multicast DNS (default true)
-  -d, --directory string              Path to the directory to serve. This can be an absolute path or a path relative to the current directory (default ".")
+  -d, --directory string                Path to the directory to serve. This can be an absolute path or a path relative to the current directory (default ".")
-  -f, --fs-provider int               0 means local filesystem, 1 Amazon S3 compatible, 2 Google Cloud Storage
+  -f, --fs-provider int                 0 means local filesystem, 1 Amazon S3 compatible, 2 Google Cloud Storage
+      --gcs-automatic-credentials int   0 means explicit credentials using a JSON credentials file, 1 automatic (default 1)
       --gcs-bucket string
-      --gcs-credentials-file string   Google Cloud Storage JSON credentials file
+      --gcs-credentials-file string     Google Cloud Storage JSON credentials file
-      --gcs-key-prefix string         Allows to restrict access to the virtual folder identified by this prefix and its contents
+      --gcs-key-prefix string           Allows to restrict access to the virtual folder identified by this prefix and its contents
       --gcs-storage-class string
-  -h, --help                          help for portable
+  -h, --help                            help for portable
-  -l, --log-file-path string          Leave empty to disable logging
+  -l, --log-file-path string            Leave empty to disable logging
-  -p, --password string               Leave empty to use an auto generated value
+  -p, --password string                 Leave empty to use an auto generated value
-  -g, --permissions strings           User's permissions. "*" means any permission (default [list,download])
+  -g, --permissions strings             User's permissions. "*" means any permission (default [list,download])
   -k, --public-key strings
       --s3-access-key string
       --s3-access-secret string
       --s3-bucket string
       --s3-endpoint string
-      --s3-key-prefix string          Allows to restrict access to the virtual folder identified by this prefix and its contents
+      --s3-key-prefix string            Allows to restrict access to the virtual folder identified by this prefix and its contents
       --s3-region string
       --s3-storage-class string
-  -s, --sftpd-port int                0 means a random non privileged port
+  -s, --sftpd-port int                  0 means a random non privileged port
-  -c, --ssh-commands strings          SSH commands to enable. "*" means any supported SSH command including scp (default [md5sum,sha1sum,cd,pwd])
+  -c, --ssh-commands strings            SSH commands to enable. "*" means any supported SSH command including scp (default [md5sum,sha1sum,cd,pwd])
-  -u, --username string               Leave empty to use an auto generated value
+  -u, --username string                 Leave empty to use an auto generated value
 ```
 
 In portable mode SFTPGo can advertise the SFTP service and, optionally, the credentials via multicast DNS, so there is a standard way to discover the service and to automatically connect to it.
@@ -696,6 +697,7 @@ For each account the following properties can be configured:
 - `s3_key_prefix`, allows to restrict access to the virtual folder identified by this prefix and its contents
 - `gcs_bucket`, required for GCS filesystem
 - `gcs_credentials`, Google Cloud Storage JSON credentials base64 encoded
+- `gcs_automatic_credentials`, integer. Set to 1 to use Application Default Credentials strategy or set to 0 to use explicit credentials via `gcs_credentials`
 - `gcs_storage_class`
 - `gcs_key_prefix`, allows to restrict access to the virtual folder identified by this prefix and its contents
 

cmd/portable.go

@@ -35,6 +35,7 @@ var (
 	portableS3KeyPrefix          string
 	portableGCSBucket            string
 	portableGCSCredentialsFile   string
+	portableGCSAutoCredentials   int
 	portableGCSStorageClass      string
 	portableGCSKeyPrefix         string
 	portableCmd                  = &cobra.Command{
@@ -48,12 +49,16 @@ Please take a look at the usage below to customize the serving parameters`,
 		Run: func(cmd *cobra.Command, args []string) {
 			portableDir := directoryToServe
 			if !filepath.IsAbs(portableDir) {
-				portableDir, _ = filepath.Abs(portableDir)
+				if portableFsProvider == 0 {
+					portableDir, _ = filepath.Abs(portableDir)
+				} else {
+					portableDir = os.TempDir()
+				}
 			}
 			permissions := make(map[string][]string)
 			permissions["/"] = portablePermissions
 			portableGCSCredentials := ""
-			if portableFsProvider == 2 {
+			if portableFsProvider == 2 && len(portableGCSCredentialsFile) > 0 {
 				fi, err := os.Stat(portableGCSCredentialsFile)
 				if err != nil {
 					fmt.Printf("Invalid GCS credentials file: %v\n", err)
@@ -69,6 +74,7 @@ Please take a look at the usage below to customize the serving parameters`,
 					fmt.Printf("Unable to read credentials file: %v\n", err)
 				}
 				portableGCSCredentials = base64.StdEncoding.EncodeToString(creds)
+				portableGCSAutoCredentials = 0
 			}
 			service := service.Service{
 				ConfigDir:     defaultConfigDir,
@@ -100,10 +106,11 @@ Please take a look at the usage below to customize the serving parameters`,
 							KeyPrefix:    portableS3KeyPrefix,
 						},
 						GCSConfig: vfs.GCSFsConfig{
-							Bucket:       portableGCSBucket,
+							Bucket:               portableGCSBucket,
-							Credentials:  portableGCSCredentials,
+							Credentials:          portableGCSCredentials,
-							StorageClass: portableGCSStorageClass,
+							AutomaticCredentials: portableGCSAutoCredentials,
-							KeyPrefix:    portableGCSKeyPrefix,
+							StorageClass:         portableGCSStorageClass,
+							KeyPrefix:            portableGCSKeyPrefix,
 						},
 					},
 				},
@@ -147,5 +154,7 @@ func init() {
 	portableCmd.Flags().StringVar(&portableGCSKeyPrefix, "gcs-key-prefix", "", "Allows to restrict access to the virtual folder "+
 		"identified by this prefix and its contents")
 	portableCmd.Flags().StringVar(&portableGCSCredentialsFile, "gcs-credentials-file", "", "Google Cloud Storage JSON credentials file")
+	portableCmd.Flags().IntVar(&portableGCSAutoCredentials, "gcs-automatic-credentials", 1, "0 means explicit credentials using a JSON "+
+		"credentials file, 1 automatic")
 	rootCmd.AddCommand(portableCmd)
 }

dataprovider/dataprovider.go

@@ -813,6 +813,9 @@ func addCredentialsToUser(user *User) error {
 	if user.FsConfig.Provider != 2 {
 		return nil
 	}
+	if user.FsConfig.GCSConfig.AutomaticCredentials > 0 {
+		return nil
+	}
 	cred, err := ioutil.ReadFile(user.getGCSCredentialsFilePath())
 	if err != nil {
 		return err

dataprovider/user.go

@@ -419,10 +419,11 @@ func (u *User) getACopy() User {
 			KeyPrefix:    u.FsConfig.S3Config.KeyPrefix,
 		},
 		GCSConfig: vfs.GCSFsConfig{
-			Bucket:         u.FsConfig.GCSConfig.Bucket,
+			Bucket:               u.FsConfig.GCSConfig.Bucket,
-			CredentialFile: u.FsConfig.GCSConfig.CredentialFile,
+			CredentialFile:       u.FsConfig.GCSConfig.CredentialFile,
-			StorageClass:   u.FsConfig.GCSConfig.StorageClass,
+			AutomaticCredentials: u.FsConfig.GCSConfig.AutomaticCredentials,
-			KeyPrefix:      u.FsConfig.GCSConfig.KeyPrefix,
+			StorageClass:         u.FsConfig.GCSConfig.StorageClass,
+			KeyPrefix:            u.FsConfig.GCSConfig.KeyPrefix,
 		},
 	}
 

httpd/api_utils.go

@@ -462,6 +462,9 @@ func compareUserFsConfig(expected *dataprovider.User, actual *dataprovider.User)
 		expected.FsConfig.GCSConfig.KeyPrefix+"/" != actual.FsConfig.GCSConfig.KeyPrefix {
 		return errors.New("GCS key prefix mismatch")
 	}
+	if expected.FsConfig.GCSConfig.AutomaticCredentials != actual.FsConfig.GCSConfig.AutomaticCredentials {
+		return errors.New("GCS automatic credentials mismatch")
+	}
 	return nil
 }
 

httpd/httpd_test.go

@@ -352,6 +352,7 @@ func TestAddUserInvalidFsConfig(t *testing.T) {
 	}
 	u.FsConfig.GCSConfig.KeyPrefix = "somedir/subdir/"
 	u.FsConfig.GCSConfig.Credentials = ""
+	u.FsConfig.GCSConfig.AutomaticCredentials = 0
 	_, _, err = httpd.AddUser(u, http.StatusBadRequest)
 	if err != nil {
 		t.Errorf("unexpected error adding user with invalid fs config: %v", err)
@@ -519,6 +520,14 @@ func TestUserGCSConfig(t *testing.T) {
 	if err != nil {
 		t.Errorf("unable to add user: %v", err)
 	}
+	os.RemoveAll(credentialsPath)
+	os.MkdirAll(credentialsPath, 0700)
+	user.FsConfig.GCSConfig.Credentials = ""
+	user.FsConfig.GCSConfig.AutomaticCredentials = 1
+	user, _, err = httpd.UpdateUser(user, http.StatusOK)
+	if err != nil {
+		t.Errorf("unable to update user: %v", err)
+	}
 	user.FsConfig.Provider = 1
 	user.FsConfig.S3Config.Bucket = "test1"
 	user.FsConfig.S3Config.Region = "us-east-1"
@@ -1937,6 +1946,26 @@ func TestWebUserGCSMock(t *testing.T) {
 	if updateUser.FsConfig.GCSConfig.KeyPrefix != user.FsConfig.GCSConfig.KeyPrefix {
 		t.Error("GCS key prefix mismatch")
 	}
+	form.Set("gcs_auto_credentials", "on")
+	b, contentType, _ = getMultipartFormData(form, "", "")
+	req, _ = http.NewRequest(http.MethodPost, webUserPath+"/"+strconv.FormatInt(user.ID, 10), &b)
+	req.Header.Set("Content-Type", contentType)
+	rr = executeRequest(req)
+	checkResponseCode(t, http.StatusSeeOther, rr.Code)
+	req, _ = http.NewRequest(http.MethodGet, userPath+"?limit=1&offset=0&order=ASC&username="+user.Username, nil)
+	rr = executeRequest(req)
+	checkResponseCode(t, http.StatusOK, rr.Code)
+	err = render.DecodeJSON(rr.Body, &users)
+	if err != nil {
+		t.Errorf("Error decoding users: %v", err)
+	}
+	if len(users) != 1 {
+		t.Errorf("1 user is expected")
+	}
+	updateUser = users[0]
+	if updateUser.FsConfig.GCSConfig.AutomaticCredentials != 1 {
+		t.Error("GCS automatic credentials mismatch")
+	}
 	req, _ = http.NewRequest(http.MethodDelete, userPath+"/"+strconv.FormatInt(user.ID, 10), nil)
 	rr = executeRequest(req)
 	checkResponseCode(t, http.StatusOK, rr.Code)

httpd/internal_test.go

@@ -286,8 +286,13 @@ func TestCompareUserFsConfig(t *testing.T) {
 		t.Errorf("S3 key prefix does not match")
 	}
 	expected.FsConfig.S3Config.KeyPrefix = ""
+}
+
+func TestCompareUserGCSConfig(t *testing.T) {
+	expected := &dataprovider.User{}
+	actual := &dataprovider.User{}
 	expected.FsConfig.GCSConfig.KeyPrefix = "somedir/subdir"
-	err = compareUserFsConfig(expected, actual)
+	err := compareUserFsConfig(expected, actual)
 	if err == nil {
 		t.Errorf("GCS key prefix does not match")
 	}
@@ -304,6 +309,12 @@ func TestCompareUserFsConfig(t *testing.T) {
 		t.Errorf("GCS storage class does not match")
 	}
 	expected.FsConfig.GCSConfig.StorageClass = ""
+	expected.FsConfig.GCSConfig.AutomaticCredentials = 1
+	err = compareUserFsConfig(expected, actual)
+	if err == nil {
+		t.Errorf("GCS automatic credentials does not match")
+	}
+	expected.FsConfig.GCSConfig.AutomaticCredentials = 0
 }
 
 func TestGCSWebInvalidFormFile(t *testing.T) {

httpd/schema/openapi.yaml

@@ -2,7 +2,7 @@ openapi: 3.0.1
 info:
   title: SFTPGo
   description: 'SFTPGo REST API'
-  version: 1.7.0
+  version: 1.8.0
 
 servers:
 - url: /api/v1
@@ -987,6 +987,16 @@ components:
           type: string
           format: byte
           description: Google Cloud Storage JSON credentials base64 encoded. This field must be populated only when adding/updating an user. It will be always omitted, since there are sensitive data, when you search/get users. The credentials will be stored in the configured "credentials_path"
+        automatic_credentials:
+          type: integer
+          nullable: true
+          enum:
+            - 0
+            - 1
+          description: >
+            Automatic credentials:
+              * `0` - disabled, explicit credentials, using a JSON credentials file, must be provided. This is the default value if the field is null
+              * `1` - enabled, we try to use the Application Default Credentials (ADC) strategy to find your application's credentials
         storage_class:
           type: string
         key_prefix:

httpd/web.go

@@ -246,6 +246,12 @@ func getFsConfigFromUserPostFields(r *http.Request) (dataprovider.Filesystem, er
 		fs.GCSConfig.Bucket = r.Form.Get("gcs_bucket")
 		fs.GCSConfig.StorageClass = r.Form.Get("gcs_storage_class")
 		fs.GCSConfig.KeyPrefix = r.Form.Get("gcs_key_prefix")
+		autoCredentials := r.Form.Get("gcs_auto_credentials")
+		if len(autoCredentials) > 0 {
+			fs.GCSConfig.AutomaticCredentials = 1
+		} else {
+			fs.GCSConfig.AutomaticCredentials = 0
+		}
 		credentials, _, err := r.FormFile("gcs_credential_file")
 		if err == http.ErrMissingFile {
 			return fs, nil
@@ -262,6 +268,7 @@ func getFsConfigFromUserPostFields(r *http.Request) (dataprovider.Filesystem, er
 			return fs, err
 		}
 		fs.GCSConfig.Credentials = base64.StdEncoding.EncodeToString(fileBytes)
+		fs.GCSConfig.AutomaticCredentials = 0
 	}
 	return fs, nil
 }

scripts/sftpgo_api_cli.py

@@ -75,7 +75,8 @@ class SFTPGoApiRequests:
 					max_sessions=0, quota_size=0, quota_files=0, permissions={}, upload_bandwidth=0, download_bandwidth=0,
 					status=1, expiration_date=0, allowed_ip=[], denied_ip=[], fs_provider='local', s3_bucket='',
 					s3_region='', s3_access_key='', s3_access_secret='', s3_endpoint='', s3_storage_class='',
-					s3_key_prefix='', gcs_bucket='', gcs_key_prefix='', gcs_storage_class='', gcs_credentials_file=''):
+					s3_key_prefix='', gcs_bucket='', gcs_key_prefix='', gcs_storage_class='', gcs_credentials_file='',
+					gcs_automatic_credentials='automatic'):
 		user = {'id':user_id, 'username':username, 'uid':uid, 'gid':gid,
 			'max_sessions':max_sessions, 'quota_size':quota_size, 'quota_files':quota_files,
 			'upload_bandwidth':upload_bandwidth, 'download_bandwidth':download_bandwidth,
@@ -95,7 +96,8 @@ class SFTPGoApiRequests:
 			user.update({'filters':self.buildFilters(allowed_ip, denied_ip)})
 		user.update({'filesystem':self.buildFsConfig(fs_provider, s3_bucket, s3_region, s3_access_key, s3_access_secret,
 													s3_endpoint, s3_storage_class, s3_key_prefix, gcs_bucket,
-													gcs_key_prefix, gcs_storage_class, gcs_credentials_file)})
+													gcs_key_prefix, gcs_storage_class, gcs_credentials_file,
+													gcs_automatic_credentials)})
 		return user
 
 	def buildPermissions(self, root_perms, subdirs_perms):
@@ -130,7 +132,8 @@ class SFTPGoApiRequests:
 		return filters
 
 	def buildFsConfig(self, fs_provider, s3_bucket, s3_region, s3_access_key, s3_access_secret, s3_endpoint,
-					s3_storage_class, s3_key_prefix, gcs_bucket, gcs_key_prefix, gcs_storage_class, gcs_credentials_file):
+					s3_storage_class, s3_key_prefix, gcs_bucket, gcs_key_prefix, gcs_storage_class,
+					gcs_credentials_file, gcs_automatic_credentials):
 		fs_config = {'provider':0}
 		if fs_provider == 'S3':
 			s3config = {'bucket':s3_bucket, 'region':s3_region, 'access_key':s3_access_key, 'access_secret':
@@ -139,9 +142,14 @@ class SFTPGoApiRequests:
 			fs_config.update({'provider':1, 's3config':s3config})
 		elif fs_provider == 'GCS':
 			gcsconfig = {'bucket':gcs_bucket, 'key_prefix':gcs_key_prefix, 'storage_class':gcs_storage_class}
+			if gcs_automatic_credentials == "automatic":
+				gcsconfig.update({'automatic_credentials':1})
+			else:
+				gcsconfig.update({'automatic_credentials':0})
 			if gcs_credentials_file:
 				with open(gcs_credentials_file) as creds:
-					gcsconfig.update({'credentials':base64.b64encode(creds.read().encode('UTF-8')).decode('UTF-8')})
+					gcsconfig.update({'credentials':base64.b64encode(creds.read().encode('UTF-8')).decode('UTF-8'),
+									'automatic_credentials':0})
 			fs_config.update({'provider':2, 'gcsconfig':gcsconfig})
 		return fs_config
 
@@ -158,12 +166,12 @@ class SFTPGoApiRequests:
 			quota_files=0, perms=[], upload_bandwidth=0, download_bandwidth=0, status=1, expiration_date=0,
 			subdirs_permissions=[], allowed_ip=[], denied_ip=[], fs_provider='local', s3_bucket='', s3_region='',
 			s3_access_key='', s3_access_secret='', s3_endpoint='', s3_storage_class='', s3_key_prefix='', gcs_bucket='',
-			gcs_key_prefix='', gcs_storage_class='', gcs_credentials_file=''):
+			gcs_key_prefix='', gcs_storage_class='', gcs_credentials_file='', gcs_automatic_credentials='automatic'):
 		u = self.buildUserObject(0, username, password, public_keys, home_dir, uid, gid, max_sessions,
 			quota_size, quota_files, self.buildPermissions(perms, subdirs_permissions), upload_bandwidth, download_bandwidth,
 			status, expiration_date, allowed_ip, denied_ip, fs_provider, s3_bucket, s3_region, s3_access_key,
 			s3_access_secret, s3_endpoint, s3_storage_class, s3_key_prefix, gcs_bucket, gcs_key_prefix, gcs_storage_class,
-			gcs_credentials_file)
+			gcs_credentials_file, gcs_automatic_credentials)
 		r = requests.post(self.userPath, json=u, auth=self.auth, verify=self.verify)
 		self.printResponse(r)
 
@@ -171,12 +179,13 @@ class SFTPGoApiRequests:
 				quota_size=0, quota_files=0, perms=[], upload_bandwidth=0, download_bandwidth=0, status=1,
 				expiration_date=0, subdirs_permissions=[], allowed_ip=[], denied_ip=[], fs_provider='local',
 				s3_bucket='', s3_region='', s3_access_key='', s3_access_secret='', s3_endpoint='', s3_storage_class='',
-				s3_key_prefix='', gcs_bucket='', gcs_key_prefix='', gcs_storage_class='', gcs_credentials_file=''):
+				s3_key_prefix='', gcs_bucket='', gcs_key_prefix='', gcs_storage_class='', gcs_credentials_file='',
+				gcs_automatic_credentials='automatic'):
 		u = self.buildUserObject(user_id, username, password, public_keys, home_dir, uid, gid, max_sessions,
 			quota_size, quota_files, self.buildPermissions(perms, subdirs_permissions), upload_bandwidth, download_bandwidth,
 			status, expiration_date, allowed_ip, denied_ip, fs_provider, s3_bucket, s3_region, s3_access_key,
 			s3_access_secret, s3_endpoint, s3_storage_class, s3_key_prefix, gcs_bucket, gcs_key_prefix, gcs_storage_class,
-			gcs_credentials_file)
+			gcs_credentials_file, gcs_automatic_credentials)
 		r = requests.put(urlparse.urljoin(self.userPath, 'user/' + str(user_id)), json=u, auth=self.auth, verify=self.verify)
 		self.printResponse(r)
 
@@ -448,6 +457,8 @@ def addCommonUserArguments(parser):
 					' Default: %(default)s')
 	parser.add_argument('--gcs-storage-class', type=str, default='', help='Default: %(default)s')
 	parser.add_argument('--gcs-credentials-file', type=str, default='', help='Default: %(default)s')
+	parser.add_argument('--gcs-automatic-credentials', type=str, default='automatic', choices=['explicit', 'automatic'],
+					help='If you provide a credentials file this argument will be setted to "explicit". Default: %(default)s')
 
 
 if __name__ == '__main__':
@@ -558,7 +569,7 @@ if __name__ == '__main__':
 				args.status, getDatetimeAsMillisSinceEpoch(args.expiration_date), args.subdirs_permissions, args.allowed_ip,
 				args.denied_ip, args.fs, args.s3_bucket, args.s3_region, args.s3_access_key, args.s3_access_secret,
 				args.s3_endpoint, args.s3_storage_class, args.s3_key_prefix, args.gcs_bucket, args.gcs_key_prefix,
-				args.gcs_storage_class, args.gcs_credentials_file)
+				args.gcs_storage_class, args.gcs_credentials_file, args.gcs_automatic_credentials)
 	elif args.command == 'update-user':
 		api.updateUser(args.id, args.username, args.password, args.public_keys, args.home_dir, args.uid, args.gid,
 					args.max_sessions, args.quota_size, args.quota_files, args.permissions, args.upload_bandwidth,
@@ -566,7 +577,7 @@ if __name__ == '__main__':
 					args.subdirs_permissions, args.allowed_ip, args.denied_ip, args.fs, args.s3_bucket, args.s3_region,
 					args.s3_access_key, args.s3_access_secret, args.s3_endpoint, args.s3_storage_class,
 					args.s3_key_prefix, args.gcs_bucket, args.gcs_key_prefix, args.gcs_storage_class,
-					args.gcs_credentials_file)
+					args.gcs_credentials_file, args.gcs_automatic_credentials)
 	elif args.command == 'delete-user':
 		api.deleteUser(args.id)
 	elif args.command == 'get-users':

service/service.go

@@ -172,52 +172,60 @@ func (s *Service) StartPortableMode(sftpdPort int, enabledSSHCommands []string,
 	config.SetSFTPDConfig(sftpdConf)
 
 	err = s.Start()
-	if err == nil {
+	if err != nil {
-		var mDNSService *zeroconf.Server
+		return err
-		var err error
-		if advertiseService {
-			version := utils.GetAppVersion()
-			meta := []string{
-				fmt.Sprintf("version=%v", version.GetVersionAsString()),
-			}
-			if advertiseCredentials {
-				logger.InfoToConsole("Advertising credentials via multicast DNS")
-				meta = append(meta, fmt.Sprintf("user=%v", s.PortableUser.Username))
-				if len(s.PortableUser.Password) > 0 {
-					meta = append(meta, fmt.Sprintf("password=%v", s.PortableUser.Password))
-				} else {
-					logger.InfoToConsole("Unable to advertise key based credentials via multicast DNS, we don't have the private key")
-				}
-			}
-			mDNSService, err = zeroconf.Register(
-				fmt.Sprintf("SFTPGo portable %v", sftpdConf.BindPort), // service instance name
-				"_sftp-ssh._tcp",   // service type and protocol
-				"local.",           // service domain
-				sftpdConf.BindPort, // service port
-				meta,               // service metadata
-				nil,                // register on all network interfaces
-			)
-			if err != nil {
-				mDNSService = nil
-				logger.WarnToConsole("Unable to advertise SFTP service via multicast DNS: %v", err)
-			} else {
-				logger.InfoToConsole("SFTP service advertised via multicast DNS")
-			}
-
-		}
-		sig := make(chan os.Signal, 1)
-		signal.Notify(sig, os.Interrupt, syscall.SIGTERM)
-		go func() {
-			<-sig
-			if mDNSService != nil {
-				logger.InfoToConsole("unregistering multicast DNS service")
-				mDNSService.Shutdown()
-			}
-			s.Stop()
-		}()
-		logger.InfoToConsole("Portable mode ready, SFTP port: %v, user: %#v, password: %#v, public keys: %v, directory: %#v, "+
-			"permissions: %v, enabled ssh commands: %v", sftpdConf.BindPort, s.PortableUser.Username, s.PortableUser.Password,
-			s.PortableUser.PublicKeys, s.PortableUser.HomeDir, s.PortableUser.Permissions, sftpdConf.EnabledSSHCommands)
 	}
-	return err
+	var mDNSService *zeroconf.Server
+	if advertiseService {
+		version := utils.GetAppVersion()
+		meta := []string{
+			fmt.Sprintf("version=%v", version.GetVersionAsString()),
+		}
+		if advertiseCredentials {
+			logger.InfoToConsole("Advertising credentials via multicast DNS")
+			meta = append(meta, fmt.Sprintf("user=%v", s.PortableUser.Username))
+			if len(s.PortableUser.Password) > 0 {
+				meta = append(meta, fmt.Sprintf("password=%v", s.PortableUser.Password))
+			} else {
+				logger.InfoToConsole("Unable to advertise key based credentials via multicast DNS, we don't have the private key")
+			}
+		}
+		mDNSService, err = zeroconf.Register(
+			fmt.Sprintf("SFTPGo portable %v", sftpdConf.BindPort), // service instance name
+			"_sftp-ssh._tcp",   // service type and protocol
+			"local.",           // service domain
+			sftpdConf.BindPort, // service port
+			meta,               // service metadata
+			nil,                // register on all network interfaces
+		)
+		if err != nil {
+			mDNSService = nil
+			logger.WarnToConsole("Unable to advertise SFTP service via multicast DNS: %v", err)
+		} else {
+			logger.InfoToConsole("SFTP service advertised via multicast DNS")
+		}
+
+	}
+	sig := make(chan os.Signal, 1)
+	signal.Notify(sig, os.Interrupt, syscall.SIGTERM)
+	go func() {
+		<-sig
+		if mDNSService != nil {
+			logger.InfoToConsole("unregistering multicast DNS service")
+			mDNSService.Shutdown()
+		}
+		s.Stop()
+	}()
+	var dirToServe string
+	if s.PortableUser.FsConfig.Provider == 1 {
+		dirToServe = s.PortableUser.FsConfig.S3Config.KeyPrefix
+	} else if s.PortableUser.FsConfig.Provider == 2 {
+		dirToServe = s.PortableUser.FsConfig.GCSConfig.KeyPrefix
+	} else {
+		dirToServe = s.PortableUser.HomeDir
+	}
+	logger.InfoToConsole("Portable mode ready, SFTP port: %v, user: %#v, password: %#v, public keys: %v, directory: %#v, "+
+		"permissions: %v, enabled ssh commands: %v", sftpdConf.BindPort, s.PortableUser.Username, s.PortableUser.Password,
+		s.PortableUser.PublicKeys, dirToServe, s.PortableUser.Permissions, sftpdConf.EnabledSSHCommands)
+	return nil
 }

templates/user.html

@@ -203,13 +203,13 @@
     </div>
 
     <div class="form-group row s3">
-        <label for="idS3Bucket" class="col-sm-2 col-form-label">S3 Bucket</label>
+        <label for="idS3Bucket" class="col-sm-2 col-form-label">Bucket</label>
         <div class="col-sm-3">
             <input type="text" class="form-control" id="idS3Bucket" name="s3_bucket" placeholder=""
                 value="{{.User.FsConfig.S3Config.Bucket}}" maxlength="255">
         </div>
         <div class="col-sm-2"></div>
-        <label for="idS3Region" class="col-sm-2 col-form-label">S3 Region</label>
+        <label for="idS3Region" class="col-sm-2 col-form-label">Region</label>
         <div class="col-sm-3">
             <input type="text" class="form-control" id="idS3Region" name="s3_region" placeholder=""
                 value="{{.User.FsConfig.S3Config.Region}}" maxlength="255">
@@ -217,13 +217,13 @@
     </div>
 
     <div class="form-group row s3">
-        <label for="idS3AccessKey" class="col-sm-2 col-form-label">S3 Access Key</label>
+        <label for="idS3AccessKey" class="col-sm-2 col-form-label">Access Key</label>
         <div class="col-sm-3">
             <input type="text" class="form-control" id="idS3AccessKey" name="s3_access_key" placeholder=""
                 value="{{.User.FsConfig.S3Config.AccessKey}}" maxlength="255">
         </div>
         <div class="col-sm-2"></div>
-        <label for="idS3AccessSecret" class="col-sm-2 col-form-label">S3 Access Secret</label>
+        <label for="idS3AccessSecret" class="col-sm-2 col-form-label">Access Secret</label>
         <div class="col-sm-3">
             <input type="text" class="form-control" id="idS3AccessSecret" name="s3_access_secret" placeholder=""
                 value="{{.User.FsConfig.S3Config.AccessSecret}}" maxlength="1000">
@@ -231,13 +231,13 @@
     </div>
 
     <div class="form-group row s3">
-        <label for="idS3StorageClass" class="col-sm-2 col-form-label">S3 Storage Class</label>
+        <label for="idS3StorageClass" class="col-sm-2 col-form-label">Storage Class</label>
         <div class="col-sm-3">
             <input type="text" class="form-control" id="idS3StorageClass" name="s3_storage_class" placeholder=""
                 value="{{.User.FsConfig.S3Config.StorageClass}}" maxlength="1000">
         </div>
         <div class="col-sm-2"></div>
-        <label for="idS3Endpoint" class="col-sm-2 col-form-label">S3 Endpoint</label>
+        <label for="idS3Endpoint" class="col-sm-2 col-form-label">Endpoint</label>
         <div class="col-sm-3">
             <input type="text" class="form-control" id="idS3Endpoint" name="s3_endpoint" placeholder=""
                 value="{{.User.FsConfig.S3Config.Endpoint}}" maxlength="255">
@@ -245,7 +245,7 @@
     </div>
 
     <div class="form-group row s3">
-        <label for="idS3KeyPrefix" class="col-sm-2 col-form-label">S3 Key Prefix</label>
+        <label for="idS3KeyPrefix" class="col-sm-2 col-form-label">Key Prefix</label>
         <div class="col-sm-10">
             <input type="text" class="form-control" id="idS3KeyPrefix" name="s3_key_prefix" placeholder=""
                 value="{{.User.FsConfig.S3Config.KeyPrefix}}" maxlength="255" aria-describedby="S3KeyPrefixHelpBlock">
@@ -256,7 +256,7 @@
     </div>
 
     <div class="form-group row gcs">
-        <label for="idGCSBucket" class="col-sm-2 col-form-label">GCS Bucket</label>
+        <label for="idGCSBucket" class="col-sm-2 col-form-label">Bucket</label>
         <div class="col-sm-10">
             <input type="text" class="form-control" id="idGCSBucket" name="gcs_bucket" placeholder=""
                 value="{{.User.FsConfig.GCSConfig.Bucket}}" maxlength="255">
@@ -264,7 +264,7 @@
     </div>
 
     <div class="form-group row gcs">
-        <label for="idGCSCredentialFile" class="col-sm-2 col-form-label">GCS Credentials file</label>
+        <label for="idGCSCredentialFile" class="col-sm-2 col-form-label">Credentials file</label>
         <div class="col-sm-4">
             <input type="file" class="form-control-file" id="idGCSCredentialFile" name="gcs_credential_file"
                 aria-describedby="GCSCredentialsHelpBlock">
@@ -273,15 +273,23 @@
             </small>
         </div>
         <div class="col-sm-1"></div>
-        <label for="idGCSStorageClass" class="col-sm-2 col-form-label">GCS Storage Class</label>
+        <label for="idGCSStorageClass" class="col-sm-2 col-form-label">Storage Class</label>
         <div class="col-sm-3">
             <input type="text" class="form-control" id="idGCSStorageClass" name="gcs_storage_class" placeholder=""
                 value="{{.User.FsConfig.GCSConfig.StorageClass}}" maxlength="255">
         </div>
     </div>
 
+    <div class="form-group gcs">
+        <div class="form-check">
+            <input type="checkbox" class="form-check-input" id="idGCSAutoCredentials" name="gcs_auto_credentials"
+                {{if gt .User.FsConfig.GCSConfig.AutomaticCredentials 0}}checked{{end}}>
+            <label for="idGCSAutoCredentials" class="form-check-label">Automatic credentials</label>
+        </div>
+    </div>
+
     <div class="form-group row gcs">
-        <label for="idGCSKeyPrefix" class="col-sm-2 col-form-label">GCS Key Prefix</label>
+        <label for="idGCSKeyPrefix" class="col-sm-2 col-form-label">Key Prefix</label>
         <div class="col-sm-10">
             <input type="text" class="form-control" id="idGCSKeyPrefix" name="gcs_key_prefix" placeholder=""
                 value="{{.User.FsConfig.GCSConfig.KeyPrefix}}" maxlength="255" aria-describedby="GCSKeyPrefixHelpBlock">
@@ -341,12 +349,15 @@
     function onFilesystemChanged(val){
         if (val == '1'){
             $('.form-group.row.gcs').hide();
+            $('.form-group.gcs').hide();
             $('.form-group.row.s3').show();
         } else if (val == '2'){
             $('.form-group.row.gcs').show();
+            $('.form-group.gcs').show();
             $('.form-group.row.s3').hide();
         } else {
             $('.form-group.row.gcs').hide();
+            $('.form-group.gcs').hide();
             $('.form-group.row.s3').hide();
         }
     }

vfs/gcsfs.go

@@ -21,10 +21,8 @@ import (
 )
 
 var (
-	// we cannot use attrs selection until this bug is fixed:
+	// we can use fields selection only when we don't need directory-like results
-	//
+	// with folders
-	// https://github.com/googleapis/google-cloud-go/issues/1763
-	//
 	gcsDefaultFieldsSelection = []string{"Name", "Size", "Deleted", "Updated"}
 )
 
@@ -37,10 +35,11 @@ type GCSFsConfig struct {
 	// folder. The prefix, if not empty, must not start with "/" and must
 	// end with "/".
 	// If empty the whole bucket contents will be available
-	KeyPrefix      string `json:"key_prefix,omitempty"`
+	KeyPrefix            string `json:"key_prefix,omitempty"`
-	CredentialFile string `json:"-"`
+	CredentialFile       string `json:"-"`
-	Credentials    string `json:"credentials,omitempty"`
+	Credentials          string `json:"credentials,omitempty"`
-	StorageClass   string `json:"storage_class,omitempty"`
+	AutomaticCredentials int    `json:"automatic_credentials,omitempty"`
+	StorageClass         string `json:"storage_class,omitempty"`
 }
 
 // GCSFs is a Fs implementation for Google Cloud Storage.
@@ -67,7 +66,11 @@ func NewGCSFs(connectionID, localTempDir string, config GCSFsConfig) (Fs, error)
 		return fs, err
 	}
 	ctx := context.Background()
-	fs.svc, err = storage.NewClient(ctx, option.WithCredentialsFile(fs.config.CredentialFile))
+	if fs.config.AutomaticCredentials > 0 {
+		fs.svc, err = storage.NewClient(ctx)
+	} else {
+		fs.svc, err = storage.NewClient(ctx, option.WithCredentialsFile(fs.config.CredentialFile))
+	}
 	return fs, err
 }
 
@@ -97,10 +100,6 @@ func (fs GCSFs) Stat(name string) (os.FileInfo, error) {
 	}
 	prefix := fs.getPrefixForStat(name)
 	query := &storage.Query{Prefix: prefix, Delimiter: "/"}
-	/*err = query.SetAttrSelection(gcsDefaultFieldsSelection)
-	if err != nil {
-		return result, err
-	}*/
 	ctx, cancelFn := context.WithDeadline(context.Background(), time.Now().Add(fs.ctxTimeout))
 	defer cancelFn()
 	bkt := fs.svc.Bucket(fs.config.Bucket)
@@ -299,7 +298,7 @@ func (GCSFs) Chtimes(name string, atime, mtime time.Time) error {
 // a list of directory entries.
 func (fs GCSFs) ReadDir(dirname string) ([]os.FileInfo, error) {
 	var result []os.FileInfo
-	// dirname deve essere già cleaned
+	// dirname must be already cleaned
 	prefix := ""
 	if len(dirname) > 0 && dirname != "." {
 		prefix = strings.TrimPrefix(dirname, "/")
@@ -308,10 +307,6 @@ func (fs GCSFs) ReadDir(dirname string) ([]os.FileInfo, error) {
 		}
 	}
 	query := &storage.Query{Prefix: prefix, Delimiter: "/"}
-	/*err := query.SetAttrSelection(gcsDefaultFieldsSelection)
-	if err != nil {
-		return result, err
-	}*/
 	ctx, cancelFn := context.WithDeadline(context.Background(), time.Now().Add(fs.ctxTimeout))
 	defer cancelFn()
 	bkt := fs.svc.Bucket(fs.config.Bucket)

vfs/s3fs.go

@@ -325,7 +325,7 @@ func (S3Fs) Chtimes(name string, atime, mtime time.Time) error {
 // a list of directory entries.
 func (fs S3Fs) ReadDir(dirname string) ([]os.FileInfo, error) {
 	var result []os.FileInfo
-	// dirname deve essere già cleaned
+	// dirname must be already cleaned
 	prefix := ""
 	if dirname != "/" && dirname != "." {
 		prefix = strings.TrimPrefix(dirname, "/")

vfs/vfs.go

@@ -109,7 +109,7 @@ func ValidateGCSFsConfig(config *GCSFsConfig, credentialsFilePath string) error
 			config.KeyPrefix += "/"
 		}
 	}
-	if len(config.Credentials) == 0 {
+	if len(config.Credentials) == 0 && config.AutomaticCredentials == 0 {
 		fi, err := os.Stat(credentialsFilePath)
 		if err != nil {
 			return fmt.Errorf("invalid credentials %v", err)