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140 lines
3.3 KiB
Markdown
140 lines
3.3 KiB
Markdown
Blazer
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====
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[](https://godoc.org/github.com/kurin/blazer/b2)
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[](https://travis-ci.org/kurin/blazer)
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Blazer is a Golang client library for Backblaze's B2 object storage service.
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It is designed for simple integration with existing applications that may
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already be using S3 and Google Cloud Storage, by exporting only a few standard
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Go types.
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It implements and satisfies the [B2 integration
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checklist](https://www.backblaze.com/b2/docs/integration_checklist.html),
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automatically handling error recovery, reauthentication, and other low-level
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aspects, making it suitable to upload very large files, or over multi-day time
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scales.
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```go
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import "github.com/kurin/blazer/b2"
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```
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## Examples
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### Copy a file into B2
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```go
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func copyFile(ctx context.Context, bucket *b2.Bucket, src, dst string) error {
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f, err := file.Open(src)
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if err != nil {
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return err
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}
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defer f.Close()
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obj := bucket.Object(dst)
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w := obj.NewWriter(ctx)
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if _, err := io.Copy(w, f); err != nil {
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w.Close()
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return err
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}
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return w.Close()
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}
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```
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If the file is less than 100MB, Blazer will simply buffer the file and use the
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`b2_upload_file` API to send the file to Backblaze. If the file is greater
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than 100MB, Blazer will use B2's large file support to upload the file in 100MB
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chunks.
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### Copy a file into B2, with multiple concurrent uploads
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Uploading a large file with multiple HTTP connections is simple:
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```go
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func copyFile(ctx context.Context, bucket *b2.Bucket, writers int, src, dst string) error {
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f, err := file.Open(src)
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if err != nil {
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return err
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}
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defer f.Close()
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w := bucket.Object(dst).NewWriter(ctx)
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w.ConcurrentUploads = writers
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if _, err := io.Copy(w, f); err != nil {
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w.Close()
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return err
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}
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return w.Close()
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}
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```
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This will automatically split the file into `writers` chunks of 100MB uploads.
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Note that 100MB is the smallest chunk size that B2 supports.
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### Download a file from B2
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Downloading is as simple as uploading:
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```go
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func downloadFile(ctx context.Context, bucket *b2.Bucket, downloads int, src, dst string) error {
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r := bucket.Object(src).NewReader(ctx)
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defer r.Close()
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f, err := file.Create(dst)
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if err != nil {
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return err
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}
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r.ConcurrentDownloads = downloads
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if _, err := io.Copy(f, r); err != nil {
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f.Close()
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return err
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}
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return f.Close()
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}
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```
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### List all objects in a bucket
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```go
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func printObjects(ctx context.Context, bucket *b2.Bucket) error {
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var cur *b2.Cursor
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for {
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objs, c, err := bucket.ListObjects(ctx, 1000, cur)
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if err != nil && err != io.EOF {
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return err
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}
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for _, obj := range objs {
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fmt.Println(obj)
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}
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if err == io.EOF {
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return
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}
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cur = c
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}
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}
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```
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### Grant temporary auth to a file
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Say you have a number of files in a private bucket, and you want to allow other
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people to download some files. This is possible to do by issuing a temporary
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authorization token for the prefix of the files you want to share.
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```go
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token, err := bucket.AuthToken(ctx, "photos", time.Hour)
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```
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If successful, `token` is then an authorization token valid for one hour, which
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can be set in HTTP GET requests.
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The hostname to use when downloading files via HTTP is account-specific and can
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be found via the BaseURL method:
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```go
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base := bucket.BaseURL()
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```
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---
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This is not an official Google product.
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