afs - abstract file storage

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Please refer to CHANGELOG.md if you encounter breaking changes.

• Motivation
• Introduction
• Usage
• Matchers
• Content modifiers
• Streaming data
• Options
• Storage Implementations
• Testing mode
• Storage Manager
• GoCover
• License
• Credits and Acknowledgements

Motivation

When dealing with various storage systems, like cloud storage, SCP, container or local file system, using shared API for typical storage operation provides an excellent simplification. What's more, the ability to simulate storage-related errors like Auth or EOF allows you to test an app error handling.

Introduction

This library uses a storage manager abstraction to provide an implementation for a specific storage system with following

• CRUD Operation:

List(ctx context.Context, URL string, options ...Option) ([]Object, error)

Walk(ctx context.Context, URL string, handler OnVisit, options ...Option) error

Open(ctx context.Context, object Object, options ...Option) (io.ReadCloser, error)

OpenURL(ctx context.Context, URL string, options ...Option) (io.ReadCloser, error)


Upload(ctx context.Context, URL string, mode os.FileMode, reader io.Reader, options ...Option) error

Create(ctx context.Context, URL string, mode os.FileMode, isDir bool, options ...Option) error

Delete(ctx context.Context, URL string, options ...Option) error

• Batch uploader:

type Upload func(ctx context.Context, parent string, info os.FileInfo, reader io.Reader) error
 
Uploader(ctx context.Context, URL string, options ...Option) (Upload, io.Closer, error)

• Utilities:

Copy(ctx context.Context, sourceURL, destURL string, options ...Option) error

Move(ctx context.Context, sourceURL, destURL string, options ...Option) error

NewWriter(ctx context.Context, URL string, mode os.FileMode, options ...storage.Option) (io.WriteCloser, error)

DownloadWithURL(ctx context.Context, URL string, options ...Option) ([]byte, error)

Download(ctx context.Context, object Object, options ...Option) ([]byte, error)

URL scheme is used to identify storage system, or alternatively relative/absolute path can be used for local file storage. By default, all operations using the same baseURL share the same corresponding storage manager instance. For example, instead supplying SCP auth details for all operations, auth option can be used only once.

func main() {

    ctx := context.Background()
    {
        //auth with first call 
        fs := afs.New()
        defer fs.Close()
        keyAuth, err := scp.LocalhostKeyAuth("")
        if err != nil {
           log.Fatal(err)
        }
        reader1, err := fs.OpenURL(ctx, "scp://host1:22/myfolder/asset.txt", keyAuth)
        if err != nil {
               log.Fatal(err)
        }
        ...
        reader2, err := fs.OpenURL(ctx, "scp://host1:22/myfolder/asset.txt", keyAuth)
    }
    
    {
        //auth per baseURL 
        fs := afs.New()
        err = fs.Init(ctx, "scp://host1:22/", keyAuth)
        if err != nil {
            log.Fatal(err)
        }
        defer fs.Destroy("scp://host1:22/")
        reader, err := fs.OpenURL(ctx, "scp://host1:22/myfolder/asset.txt")
     }
}

Usage

Downloading location content

func main() {
	
    fs := afs.New()
    ctx := context.Background()
    objects, err := fs.List(ctx, "/tmp/folder")
    if err != nil {
        log.Fatal(err)
    }
    for _, object := range objects {
        fmt.Printf("%v %v\n", object.Name(), object.URL())
        if object.IsDir() {
            continue
        }
        reader, err := fs.Open(ctx, object)
        if err != nil {
            log.Fatal(err)
        }
        data, err := ioutil.ReadAll(reader)
        if err != nil {
            log.Fatal(err)
        }
        fmt.Printf("%s\n", data)
    }
}

Uploading Content

func main() {
	
    fs := afs.New()
    ctx := context.Background()
    keyAuth, err := scp.LocalhostKeyAuth("")
    if err != nil {
        log.Fatal(err)
    }
    err  = fs.Init(ctx, "scp://127.0.0.1:22/", keyAuth)
    if err != nil {
        log.Fatal(err)
    }	
    err = fs.Upload(ctx, "scp://127.0.0.1:22/folder/asset.txt", 0644, strings.NewReader("test me"))
    if err != nil {
        log.Fatal(err)
    }
    ok, err := fs.Exists(ctx, "scp://127.0.0.1:22/folder/asset.txt")
    if err != nil {
        log.Fatal(err)
    }
    fmt.Printf("has file: %v\n", ok)
    _ = fs.Delete(ctx, "scp://127.0.0.1:22/folder/asset.txt")
}

Uploading Content With Writer

func main() {
	
    fs := afs.New()
    ctx := context.Background()
    keyAuth, err := scp.LocalhostKeyAuth("")
    if err != nil {
        log.Fatal(err)
    }
    err  = fs.Init(ctx, "scp://127.0.0.1:22/", keyAuth)
    if err != nil {
        log.Fatal(err)
    }	
    writer = fs.NewWriter(ctx, "scp://127.0.0.1:22/folder/asset.txt", 0644)
    _, err := writer.Write([]byte("test me")))
    if err != nil {
        log.Fatal(err)
    }
    err = writer.Close()
    if err != nil {
        log.Fatal(err)
    }
    ok, err := fs.Exists(ctx, "scp://127.0.0.1:22/folder/asset.txt")
    if err != nil {
        log.Fatal(err)
    }
    fmt.Printf("has file: %v\n", ok)
    _ = fs.Delete(ctx, "scp://127.0.0.1:22/folder/asset.txt")
}

Data Copy

func main() {

    fs := afs.New()
    ctx := context.Background()
    keyAuth, err := scp.LocalhostKeyAuth("")
    if err != nil {
        log.Fatal(err)
    }
    err = fs.Copy(ctx, "s3://mybucket/myfolder", "scp://127.0.0.1/tmp", option.NewSource(), option.NewDest(keyAuth))
    if err != nil {
        log.Fatal(err)
    }
}

Archiving content

func main() {
	
    secretPath := path.Join(os.Getenv("HOME"), ".secret", "gcp-e2e.json")
    auth, err := gs.NewJwtConfig(option.NewLocation(secretPath))
    if err != nil {
        return
    }
    sourceURL := "mylocalPath/"
    destURL := "gs:mybucket/test.zip/zip://localhost/dir1"
    fs := afs.New()
    ctx := context.Background()
    err = fs.Copy(ctx, sourceURL, destURL, option.NewDest(auth))
    if err != nil {
        log.Fatal(err)
    }

}	

Archive Walker

Walker can be created for tar or zip archive.

func main() {
	
    ctx := context.Background()
	fs := afs.New()
	walker := tar.NewWalker(s3afs.New())
	err := fs.Copy(ctx, "/tmp/test.tar", "s3:///dest/folder/test", walker)
	if err != nil {
		log.Fatal(err)
	}

Archive Uploader

Uploader can be created for tar or zip archive.

func main() {
	
    ctx := context.Background()
	fs := afs.New()
	uploader := zip.NewBatchUploader(gsafs.New())
	err := fs.Copy(ctx, "gs:///tmp/test/data", "/tmp/data.zip", uploader)
	if err != nil {
		log.Fatal(err)
	}
}

Data Move

func main() {
	
    fs := afs.New()
	ctx := context.Background()
	keyAuth, err := scp.LocalhostKeyAuth("")
	if err != nil {
		log.Fatal(err)
	}
	err = fs.Move(ctx, "/tmp/transient/app", "scp://127.0.0.1/tmp", option.NewSource(), option.NewDest(keyAuth))
	if err != nil {
		log.Fatal(err)
	}
}	

Batch Upload

func main() {
	
    fs := afs.New()
	ctx := context.Background()
	upload, closer, err := fs.Uploader(ctx, "/tmp/clone")
	if err != nil {
		log.Fatal(err)
	}
	defer closer.Close()
	assets := []*asset.Resource{
		asset.NewFile("asset1.txt", []byte("test 1"), 0644),
		asset.NewFile("asset2.txt", []byte("test 2"), 0644),
		asset.NewDir("folder1", file.DefaultDirOsMode),
		asset.NewFile("folder1/asset1.txt", []byte("test 3"), 0644),
		asset.NewFile("folder1/asset2.txt", []byte("test 4"), 0644),
	}
	for _, asset := range assets {
		relative := ""
		var reader io.Reader
		if strings.Contains(asset.Name, "/") {
			relative, _ = path.Split(asset.Name)
		}
		if ! asset.Dir {
			reader = bytes.NewReader(asset.Data)
		}
		err = upload(ctx, relative, asset.Info(), reader)
		if err != nil {
			log.Fatal(err)
		}
	}
}

Matchers

To filter source content you can use Matcher option. The following have been implemented.

Basic Matcher

func main() {
	
    matcher, err := NewBasic("/data", ".avro", nil)
    fs := afs.New()
    ctx := context.Background()
    err := fs.Copy(ctx, "/tmp/data", "s3://mybucket/data/", matcher.Match)
    if err != nil {
        log.Fatal(err)
    }
}

Exclusion

func main() {
	
    matcher := matcher.Basic{Exclusion:".+/data/perf/\\d+/.+"}
    fs := afs.New()
    ctx := context.Background()
    err := fs.Copy(ctx, "/tmp/data", "s3://mybucket/data/", matcher.Match)
    if err != nil {
        log.Fatal(err)
    }
}

Filepath matcher

OS style filepath match, with the following terms:

• '*' matches any sequence of non-Separator characters
• '?' matches any single non-Separator character
• '[' [ '^' ] { character-range } ']'

func main() {
	
    matcher := matcher.Filepath("*.avro")
    fs := afs.New()
    ctx := context.Background()
    err := fs.Copy(ctx, "/tmp/data", "gs://mybucket/data/", matcher)
    if err != nil {
        log.Fatal(err)
    }
}	
		

Ignore Matcher

Ignore matcher represents matcher that matches file that are not in the ignore rules. The