gs

package
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 Go to latest Published: Apr 5, 2019 License: MIT Imports: 18 Imported by: 0

Documentation

Overview

Package gs Google Cloud Storage VFS implementation.

Usage

Rely on github.com/c2fo/vfs/backend 

import(
    "github.com/c2fo/vfs/backend"
    "github.com/c2fo/vfs/backend/gs"
)

func UseFs() error {
    fs, err := backend.Backend(gs.Scheme)
    ...
}

Or call directly: 

import "github.com/c2fo/vfs/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

Authentication, by default, occurs automatically when Client() is called. It looks for credentials in the following places, preferring the first location found:

  1. A JSON file whose path is specified by the GOOGLE_APPLICATION_CREDENTIALS environment variable
  2. 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.
  3. On Google App Engine it uses the appengine.AccessToken function.
  4. 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 Also

See: https://github.com/googleapis/google-cloud-go/tree/master/storage

Index

Constants

View Source 
const Scheme = "gs"

Scheme defines the filesystem type.

Variables

This section is empty.

Functions

This section is empty.

Types

type File 

type File struct {
	// contains filtered or unexported fields
}

File implements vfs.File interface for GS fs.

func (*File) Close 

func (f *File) Close() error

Close 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 (*File) CopyToFile 

func (f *File) CopyToFile(targetFile vfs.File) error

CopyToFile 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 (*File) CopyToLocation 

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 (*File) Delete 

func (f *File) Delete() error

Delete clears any local temp file, or write buffer from read/writes to the file, then makes a DeleteObject call to GCS for the file. Returns any error returned by the API.

func (*File) Exists 

func (f *File) Exists() (bool, error)

Exists returns a boolean of whether or not the object exists in GCS.

func (*File) LastModified 

func (f *File) LastModified() (*time.Time, error)

LastModified returns the 'Updated' property from the GCS attributes.

func (*File) Location 

func (f *File) Location() vfs.Location

Location returns a Location instance for the file's current location.

TODO should this be including trailing slash?

func (*File) MoveToFile 

func (f *File) MoveToFile(targetFile vfs.File) error

MoveToFile 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 (*File) MoveToLocation 

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 (*File) Name 

func (f *File) Name() string

Name returns the file name.

func (*File) Path 

func (f *File) Path() string

Path returns full path with leading slash of the GCS file key.

func (*File) Read 

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 (*File) Seek 

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 (*File) Size 

func (f *File) Size() (uint64, error)

Size returns the 'Size' property from the GCS attributes.

func (*File) String 

func (f *File) String() string

String returns the file URI string.

func (*File) URI 

func (f *File) URI() string

URI returns a full GCS URI string of the file.

func (*File) Write 

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 

type FileSystem struct {
	// contains filtered or unexported fields
}

FileSystem implements vfs.Filesystem for the GCS filesystem.

func NewFileSystem 

func NewFileSystem() *FileSystem

NewFileSystem initializer for FileSystem struct accepts google cloud storage client and returns Filesystem or error.

func (*FileSystem) Client 

func (fs *FileSystem) Client() (*storage.Client, error)

Client returns the underlying google storage client, creating it, if necessary See Overview for authentication resolution

func (*FileSystem) Name 

func (fs *FileSystem) Name() string

Name returns "Google Cloud Storage"

func (*FileSystem) NewFile 

func (fs *FileSystem) NewFile(volume string, name string) (vfs.File, error)

NewFile function returns the gcs implementation of vfs.File.

func (*FileSystem) NewLocation 

func (fs *FileSystem) NewLocation(volume string, path string) (loc vfs.Location, err error)

NewLocation function returns the GCS implementation of vfs.Location.

func (*FileSystem) Scheme 

func (fs *FileSystem) Scheme() string

Scheme return "gs" as the initial part of a file URI ie: gs://

func (*FileSystem) WithClient 

func (fs *FileSystem) WithClient(client *storage.Client) *FileSystem

WithClient passes in a google storage client and returns the filesystem (chainable)

func (*FileSystem) WithContext 

func (fs *FileSystem) WithContext(ctx context.Context) *FileSystem

WithContext passes in user context and returns the filesystem (chainable)

func (*FileSystem) WithOptions 

func (fs *FileSystem) WithOptions(opts vfs.Options) *FileSystem

WithOptions sets options for client and returns the filesystem (chainable)

type Location 

type Location struct {
	// contains filtered or unexported fields
}

Location implements vfs.Location for gs fs.

func (*Location) ChangeDir 

func (l *Location) ChangeDir(relativePath string) error

ChangeDir changes the current location's path to the new, relative path.

func (*Location) DeleteFile 

func (l *Location) DeleteFile(fileName string) error

DeleteFile deletes the file at the given path, relative to the current location.

func (*Location) Exists 

func (l *Location) Exists() (bool, error)

Exists returns whether the location exists or not. In the case of an error, false is returned.

func (*Location) FileSystem 

func (l *Location) FileSystem() vfs.FileSystem

FileSystem returns the GCS file system instance.

func (*Location) List 

func (l *Location) List() ([]string, error)

List returns a list of file name strings for the current location.

func (*Location) ListByPrefix 

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 (*Location) ListByRegex 

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 (*Location) NewFile 

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 (*Location) NewLocation 

func (l *Location) NewLocation(relativePath string) (vfs.Location, error)

NewLocation creates a new location instance relative to the current location's path.

func (*Location) Path 

func (l *Location) Path() string

Path returns the path of the file at the current location, starting with a leading '/'

func (*Location) String 

func (l *Location) String() string

String returns the full URI of the location.

func (*Location) URI 

func (l *Location) URI() string

URI returns a URI string for the GCS location.

func (*Location) Volume 

func (l *Location) Volume() string

Volume returns the GCS bucket name.

type Options 

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.

Source Files

View all Source files

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