gocloud.dev – gocloud.dev/blob/fileblob Index | Examples | Files

package fileblob

import "gocloud.dev/blob/fileblob"

Package fileblob provides a blob implementation that uses the filesystem. Use OpenBucket to construct a *blob.Bucket.

Open URLs

For blob.Open URLs, fileblob registers for the scheme "file"; URLs start with "file://" like "file:///path/to/directory". For full details, see URLOpener.

Escaping

Go CDK supports all UTF-8 strings; to make this work with providers lacking full UTF-8 support, strings must be escaped (during writes) and unescaped (during reads). The following escapes are performed for fileblob:

As

fileblob exposes the following types for As:

Example

Code:play  

package main

import (
	"context"
	"fmt"
	"io/ioutil"
	"log"
	"os"

	"gocloud.dev/blob/fileblob"
)

func main() {

	// Create a temporary directory.
	dir, err := ioutil.TempDir("", "go-cloud-fileblob-example")
	if err != nil {
		log.Fatal(err)
	}
	defer os.RemoveAll(dir)

	// Create a file-based bucket.
	b, err := fileblob.OpenBucket(dir, nil)
	if err != nil {
		log.Fatal(err)
	}

	// Now we can use b to read or write files to the container.
	ctx := context.Background()
	err = b.WriteAll(ctx, "my-key", []byte("hello world"), nil)
	if err != nil {
		log.Fatal(err)
	}
	data, err := b.ReadAll(ctx, "my-key")
	if err != nil {
		log.Fatal(err)
	}
	fmt.Println(string(data))

}

Output:

hello world
Example (Open)

Code:play  

package main

import (
	"context"
	"fmt"
	"io/ioutil"
	"log"
	"os"
	"path"

	"gocloud.dev/blob"
)

func main() {
	// Create a temporary directory.
	dir, err := ioutil.TempDir("", "go-cloud-fileblob-example")
	if err != nil {
		log.Fatal(err)
	}
	defer os.RemoveAll(dir)

	// Open creates a *blob.Bucket from a URL.
	ctx := context.Background()
	b, err := blob.OpenBucket(ctx, path.Join("file://", dir))
	if err != nil {
		log.Fatal(err)
	}

	// Now we can use b to read or write files to the container.
	err = b.WriteAll(ctx, "my-key", []byte("hello world"), nil)
	if err != nil {
		log.Fatal(err)
	}
	data, err := b.ReadAll(ctx, "my-key")
	if err != nil {
		log.Fatal(err)
	}
	fmt.Println(string(data))

}

Output:

hello world

Index

Examples

Constants 

const Scheme = "file"

Scheme is the URL scheme fileblob registers its URLOpener under on blob.DefaultMux.

Functions

func OpenBucket 

func OpenBucket(dir string, opts *Options) (*blob.Bucket, error)

OpenBucket creates a *blob.Bucket backed by the filesystem and rooted at dir, which must exist. See the package documentation for an example.

Types

type Options 

type Options struct {
	// URLSigner implements signing URLs (to allow access to a resource without
	// further authorization) and verifying that a given URL is unexpired and
	// contains a signature produced by the URLSigner.
	// URLSigner is only required for utilizing the SignedURL API.
	URLSigner URLSigner
}

Options sets options for constructing a *blob.Bucket backed by fileblob.

type URLOpener 

type URLOpener struct{}

URLOpener opens file bucket URLs like "file:///foo/bar/baz".

func (*URLOpener) OpenBucketURL 

func (*URLOpener) OpenBucketURL(ctx context.Context, u *url.URL) (*blob.Bucket, error)

OpenBucketURL opens the file bucket at the URL's path. The URL's host is ignored. If os.PathSeparator != "/", any leading "/" from the path is dropped and remaining '/' characters are converted to os.PathSeparator. No query options are supported. Examples:

type URLSigner 

type URLSigner interface {
	// URLFromKey defines how the bucket's object key will be turned
	// into a signed URL. URLFromKey must be safe to call from multiple goroutines.
	URLFromKey(ctx context.Context, key string, opts *driver.SignedURLOptions) (*url.URL, error)

	// KeyFromURL must be able to validate a URL returned from URLFromKey.
	// KeyFromURL must only return the object if if the URL is
	// both unexpired and authentic. KeyFromURL must be safe to call from
	// multiple goroutines. Implementations of KeyFromURL should not modify
	// the URL argument.
	KeyFromURL(ctx context.Context, surl *url.URL) (string, error)
}

URLSigner defines an interface for creating and verifying a signed URL for objects in a fileblob bucket. Signed URLs are typically used for granting access to an otherwise-protected resource without requiring further authentication, and callers should take care to restrict the creation of signed URLs as is appropriate for their application.

type URLSignerHMAC 

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

URLSignerHMAC signs URLs by adding the object key, expiration time, and a hash-based message authentication code (HMAC) into the query parameters. Values of URLSignerHMAC with the same secret key will accept URLs produced by others as valid.

func NewURLSignerHMAC 

func NewURLSignerHMAC(baseURL *url.URL, secretKey []byte) *URLSignerHMAC

NewURLSignerHMAC creates a URLSignerHMAC. If the secret key is empty, then NewURLSignerHMAC panics.

func (*URLSignerHMAC) KeyFromURL 

func (h *URLSignerHMAC) KeyFromURL(ctx context.Context, sURL *url.URL) (string, error)

KeyFromURL checks expiry and signature, and returns the object key only if the signed URL is both authentic and unexpired.

func (*URLSignerHMAC) URLFromKey 

func (h *URLSignerHMAC) URLFromKey(ctx context.Context, key string, opts *driver.SignedURLOptions) (*url.URL, error)

URLFromKey creates a signed URL by copying the baseURL and appending the object key, expiry, and signature as a query params.

Source Files

attrs.go fileblob.go

Version
v0.11.0
Published
Feb 28, 2019
Platform
js/wasm
Imports
21 packages
Last checked
5 hours ago –

Tools for package owners.