Package gs - Google Cloud Storage VFS implementation.
Rely on github.com/c2fo/vfs/v6/backend
import(
"github.com/c2fo/vfs/v6/backend"
"github.com/c2fo/vfs/v6/backend/gs"
)
func UseFs() error {
fs := backend.Backend(gs.Scheme)
...
}Or call directly:
import "github.com/c2fo/vfs/v6/backend/gs"
func DoSomething() {
fs := gs.NewFileSystem()
...
}gs can be augmented with the following implementation-specific methods. Backend returns vfs.FileSystem interface so it would have to be cast as gs.FileSystem to use the following:
func DoSomething() {
...
// cast if fs was created using backend.Backend(). Not necessary if created directly from gs.NewFileSystem().
fs = fs.(gs.FileSystem)
// to use your own "context"
ctx := context.Background()
fs = fs.WithContext(ctx)
// to pass in client options
fs = fs.WithOptions(
gs.Options{
CredentialFile: "/root/.gcloud/account.json",
Scopes: []string{"ScopeReadOnly"},
//default scope is "ScopeFullControl"
},
)
// to pass specific client, for instance no-auth client
ctx := context.Background()
client, _ := storage.NewClient(ctx, option.WithoutAuthentication())
fs = fs.WithClient(client)
}Authentication, by default, occurs automatically when Client() is called. It looks for credentials in the following places, preferring the first location found:
- A JSON file whose path is specified by the
GOOGLE_APPLICATION_CREDENTIALSenvironment variable - A JSON file in a location known to the gcloud command-line tool.
- On Windows, this is
%APPDATA%/gcloud/application_default_credentials.json. - On other systems,
$HOME/.config/gcloud/application_default_credentials.json.
- On Windows, this is
- On Google App Engine it uses the appengine.AccessToken function.
- On Google Compute Engine and Google App Engine Managed VMs, it fetches credentials from the metadata server.
See https://cloud.google.com/docs/authentication/production for more auth info
See: https://github.com/googleapis/google-cloud-go/tree/master/storage
const Scheme = "gs"Scheme defines the file system type.
type File struct {
}File implements vfs.File interface for GS fs.
func (f *File) Close() errorClose cleans up underlying mechanisms for reading from and writing to the file. Closes and removes the local temp file, and triggers a write to GCS of anything in the f.writeBuffer if it has been created.
func (f *File) CopyToFile(targetFile vfs.File) errorCopyToFile puts the contents of File into the targetFile passed. Uses the GCS CopierFrom method if the target file is also on GCS, otherwise uses io.Copy.
func (f *File) CopyToLocation(location vfs.Location) (vfs.File, error)CopyToLocation creates a copy of *File, using the file's current name as the new file's name at the given location. If the given location is also GCS, the GCS API for copying files will be utilized, otherwise, standard io.Copy will be done to the new file.
func (f *File) Delete(opts ...options.DeleteOption) errorDelete clears any local temp file, or write buffer from read/writes to the file, then makes a DeleteObject call to GCS for the file. If opts is of type DeleteAllVersions, DeleteObject call is made to GCS for each version of the file. Returns any error returned by the API.
func (f *File) Exists() (bool, error)Exists returns a boolean of whether or not the object exists in GCS.
func (f *File) LastModified() (*time.Time, error)LastModified returns the 'Updated' property from the GCS attributes.
func (f *File) Location() vfs.LocationLocation returns a Location instance for the file's current location.
func (f *File) MoveToFile(targetFile vfs.File) errorMoveToFile puts the contents of File into the targetFile passed using File.CopyToFile. If the copy succeeds, the source file is deleted. Any errors from the copy or delete are returned.
func (f *File) MoveToLocation(location vfs.Location) (vfs.File, error)MoveToLocation works by first calling File.CopyToLocation(vfs.Location) then, if that succeeds, it deletes the original file, returning the new file. If the copy process fails the error is returned, and the Delete isn't called. If the call to Delete fails, the error and the file generated by the copy are both returned.
func (f *File) Name() stringName returns the file name.
func (f *File) Path() stringPath returns full path with leading slash of the GCS file key.
func (f *File) Read(p []byte) (n int, err error)Read implements the standard for io.Reader. For this to work with an GCS file, a temporary local copy of the file is created, and reads work on that. This file is closed and removed upon calling f.Close()
func (f *File) Seek(offset int64, whence int) (int64, error)Seek implements the standard for io.Seeker. A temporary local copy of the GCS file is created (the same one used for Reads) which Seek() acts on. This file is closed and removed upon calling f.Close()
func (f *File) Size() (uint64, error)Size returns the 'Size' property from the GCS attributes.
func (f *File) String() stringString returns the file URI string.
func (f *File) URI() stringURI returns a full GCS URI string of the file.
func (f *File) Write(data []byte) (n int, err error)Write implements the standard for io.Writer. A buffer is added to with each subsequent write. Calling Close() will write the contents back to GCS.
type FileSystem struct {
}FileSystem implements vfs.FileSystem for the GCS file system.
func NewFileSystem() *FileSystemNewFileSystem initializer for FileSystem struct accepts google cloud storage client and returns FileSystem or error.
func (fs *FileSystem) Client() (*storage.Client, error)Client returns the underlying google storage client, creating it, if necessary See Authentication section for authentication resolution
func (fs *FileSystem) Name() stringName returns "Google Cloud Storage"
func (fs *FileSystem) NewFile(volume string, name string) (vfs.File, error)NewFile function returns the gcs implementation of vfs.File.
func (fs *FileSystem) NewLocation(volume string, path string) (loc vfs.Location, err error)NewLocation function returns the s3 implementation of vfs.Location.
func (fs *FileSystem) Scheme() stringScheme return "gs" as the initial part of a file URI ie: gs://
func (fs *FileSystem) WithClient(client *storage.Client) *FileSystemWithClient passes in a google storage client and returns the FileSystem (chainable)
func (fs *FileSystem) WithContext(ctx context.Context) *FileSystemWithContext passes in user context and returns the FileSystem (chainable)
func (fs *FileSystem) WithOptions(opts vfs.Options) *FileSystemWithOptions sets options for client and returns the FileSystem (chainable)
type Location struct {
}Location implements vfs.Location for gs fs.
func (l *Location) ChangeDir(relativePath string) errorChangeDir changes the current location's path to the new, relative path.
func (l *Location) DeleteFile(fileName string, opts ...options.DeleteOption) errorDeleteFile deletes the file at the given path, relative to the current location using given options.
func (l *Location) Exists() (bool, error)Exists returns whether the location exists or not. In the case of an error, false is returned.
func (l *Location) FileSystem() vfs.FileSystemFileSystem returns the GCS file system instance.
func (l *Location) List() ([]string, error)List returns a list of file name strings for the current location.
func (l *Location) ListByPrefix(filenamePrefix string) ([]string, error)ListByPrefix returns a slice of file base names and any error, if any prefix means filename prefix and therefore should not have slash List functions return only files List functions return only basenames
func (l *Location) ListByRegex(regex *regexp.Regexp) ([]string, error)ListByRegex returns a list of file names at the location which match the provided regular expression.
func (l *Location) NewFile(filePath string) (vfs.File, error)NewFile returns a new file instance at the given path, relative to the current location.
func (l *Location) NewLocation(relativePath string) (vfs.Location, error)NewLocation creates a new location instance relative to the current location's path.
func (l *Location) Path() stringPath returns the path of the file at the current location, starting with a leading '/'
func (l *Location) String() stringString returns the full URI of the location.
func (l *Location) URI() stringURI returns a URI string for the GCS location.
func (l *Location) Volume() stringVolume returns the GCS bucket name.
type Options struct {
APIKey string `json:"apiKey,omitempty"`
CredentialFile string `json:"credentialFilePath,omitempty"`
Endpoint string `json:"endpoint,omitempty"`
Scopes []string `json:"WithoutAuthentication,omitempty"`
}Options holds Google Cloud Storage -specific options. Currently only client options are used.