afs - abstract file storage

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 syntax of ignore borrows heavily from that of .gitignore; see https://git-scm.com/docs/gitignore or man gitignore for a full reference.

func mian(){
	
	ignoreMatcher, err := matcher.NewIgnore([]string{"*.txt", ".ignore"})
  	//or matcher.NewIgnore(option.NewLocation(".cloudignore"))
	if err != nil {
		log.Fatal(err)
	}
	fs := afs.New()
	ctx := context.Background()
	objects, err := fs.List(ctx, "/tmp/folder", ignoreMatcher.Match)
	if err != nil {
		log.Fatal(err)
	}
	for _, object := range objects {
		fmt.Printf("%v %v\n", object.Name(), object.URL())
		if object.IsDir() {
			continue
		}
	}
}

Modification Time Matcher

Modification Time Matcher represents matcher that matches file that were modified either before or after specified time.

func mian(){
	
	before, err := toolbox.TimeAt("2 days ago in UTC")
    if err != nil {
		log.Fatal(err)
	}	
	modTimeMatcher, err := matcher.NewModification(before, nil)
	if err != nil {
		log.Fatal(err)
	}
	fs := afs.New()
	ctx := context.Background()
	objects, err := fs.List(ctx, "/tmp/folder", modTimeMatcher.Match)
	if err != nil {
		log.Fatal(err)
	}
	for _, object := range objects {
		fmt.Printf("%v %v\n", object.Name(), object.URL())
		if object.IsDir() {
			continue
		}
	}
}

Content modifiers

To modify resource content on the fly you can use Modifier option.

func main() {
	fs := afs.New()
	ctx := context.Background()
	sourceURL := "file:/tmp/app.war/zip://localhost/WEB-INF/classes/config.properties"
	destURL := "file:/tmp/app.war/zip://localhost/"
	err := fs.Copy(ctx, sourceURL, destURL, modifier.Replace(map[string]string{
		"${changeMe}": os.Getenv("USER"),
	}))
	if err != nil {
		log.Fatal(err)
	}
}

package main

import (
	"context"
	"log"
	"github.com/viant/afs"
	"io"
	"fmt"
	"io/ioutil"
	"os"
	"strings"
)

func modifyContent(info os.FileInfo, reader io.ReadCloser) (closer io.ReadCloser, e error) {
   if strings.HasSuffix(info.Name() ,".info") {
       data, err := ioutil.ReadAll(reader)
       if err != nil {
           return nil, err
       }
       _ = reader.Close()
       expanded := strings.Replace(string(data), "$os.User", os.Getenv("USER"), 1)
       reader = ioutil.NopCloser(strings.NewReader(expanded))
   }
   return reader, nil
}                           

func main() {

    fs := afs.New()
    reader ,err := fs.OpenURL(context.Background(), "s3://mybucket/meta.info", modifyContent)
    if err != nil {
        log.Fatal(err)	
    }
    
    defer reader.Close()
    content, err := ioutil.ReadAll(reader)
    if err != nil {
        log.Fatal(err)	
    }
    fmt.Printf("content: %s\n", content)
	
}

Streaming data

Streaming data allows data reading and uploading in chunks with small memory footprint.


    jwtConfig, err := gs.NewJwtConfig()
	if err != nil {
		log.Fatal(err)
	}

	ctx := context.Background()
	fs := afs.New()
	sourceURL := "gs://myBucket/path/myasset.gz"
	reader, err := fs.OpenURL(ctx, sourceURL, jwtConfig, option.NewStream(64*1024*1024, 0))
	if err != nil {
		log.Fatal(err)
	}
    
	_ = os.Setenv("AWS_SDK_LOAD_CONFIG", "true")
	destURL := "s3://myBucket/path/myasset.gz"
	err = fs.Upload(ctx, destURL, 0644, reader, &option.Checksum{Skip:true})
	if err != nil {
		log.Fatal(err)
	}

    // or
    writer = fs.NewWriter(ctx, destURL, 0644, &option.Checksum{Skip:true})
    _, err = io.Copy(writer, reader)
    if err != nil {
        log.Fatal(err)
    }
    err = writer.Close()
	if err != nil {
		log.Fatal(err)
	}

Options

Page

To control number and position of listed resources you can yse page option.

Timeout

Provider specific timeout.

BasicAuth

Provides user/password auth.

Source & Dest Options

Groups options by source or destination options. This options work with Copy or Move operations.


func main() {
	
    fs := afs.New()
    secretPath :=  path.Join(os.Getenv("HOME"), ".secret","gcp.json")
    jwtConfig, err := gs.NewJwtConfig(option.NewLocation(secretPath))
    if err != nil {
    	log.Fatal(err)
    }
    sourceOptions := option.NewSource(jwtConfig)
    authConfig, err := s3.NewAuthConfig(option.NewLocation("aws.json"))
    if err != nil {
        log.Fatal(err)
    }
    destOptions := option.NewDest(authConfig)
	err = fs.Copy(ctx, "gs://mybucket/data", "s3://mybucket/data",  sourceOptions, destOptions)
}

option.Checksum skip computing checksum if Skip is set, this option allows streaming upload in chunks
option.Stream: download reader reads data with specified stream PartSize

Check out storage manager for additional options.

Storage Implementations

Testing fs

To unit test all storage operation all in memory you can use faker fs.

In addition you can use error options to test exception handling.

DownloadError


func mian() {
	fs := afs.NewFaker()
	ctx := context.Background()
	err := fs.Upload(ctx, "gs://myBucket/folder/asset.txt", 0, strings.NewReader("some data"), option.NewUploadError(io.EOF))
	if err != nil {
		log.Fatalf("expect upload error: %v", err)
	}
}

ReaderError


func mian() {
    fs := afs.NewFaker()
	ctx := context.Background()
	err := fs.Upload(ctx, "gs://myBucket/folder/asset.txt", 0, strings.NewReader("some data"), option.NewDownloadError(io.EOF))
	if err != nil {
		log.Fatal(err)
	}
	_, err = fs.OpenURL(ctx, "gs://myBucket/folder/asset.txt")
	if err != nil {
		log.Fatalf("expect download error: %v", err)
	}
}

UploadError


func mian() {
    fs := afs.NewFaker()
    ctx := context.Background()
    err := fs.Upload(ctx, "gs://myBucket/folder/asset.txt", 0, strings.NewReader("some data"), option.NewUploadError(io.EOF))
    if err != nil {
        log.Fatalf("expect upload error: %v", err)
    }
}

Code generation for static or in memory go file

Generate with mem storage

package main

import (
    "log"
    "github.com/viant/afs/parrot
)

func mian() {
  ctx := context.Background()
  err := parrot.GenerateWithMem(ctx, "pathToBinaryAsset", "gen.go", false)
  if err != nil {
    log.Fatal(err)
  }
}

Generate static data files

package main

import (
    "log"
    "github.com/viant/afs/parrot
)

func mian() {
  ctx := context.Background()
  err := parrot.Generate(ctx, "pathToBinaryAsset", "data/", false)
  if err != nil {
    log.Fatal(err)
  }
}

Test setup utilities

Package asset defines basic utilities to quickly manage asset related unit tests.


func Test_XXX(t *testing.T) {

    var useCases = []struct {
		description string
		location    string
		options     []storage.Option
		assets      []*asset.Resource
	}{

	}

	ctx := context.Background()
	for _, useCase := range useCases {
		fs := afs.New()
		mgr, err := afs.Manager(useCase.location, useCase.options...)
		if err != nil {
			log.Fatal(err)
		}
		err = asset.Create(mgr, useCase.location, useCase.assets)
		if err != nil {
			log.Fatal(err)
		}
		
		//... actual app logic

		actuals, err := asset.Load(mgr, useCase.location)
		if err != nil {
			log.Fatal(err)
		}
        for _, expect := range useCase.assets {
            actual, ok := actuals[expect.Name]
            if !assert.True(t, ok, useCase.description+": "+expect.Name+fmt.Sprintf(" - actuals: %v", actuals)) {
                continue
            }
            assert.EqualValues(t, expect.Name, actual.Name, useCase.description+" "+expect.Name)
            assert.EqualValues(t, expect.Mode, actual.Mode, useCase.description+" "+expect.Name)
            assert.EqualValues(t, expect.Dir, actual.Dir, useCase.description+" "+expect.Name)
            assert.EqualValues(t, expect.Data, actual.Data, useCase.description+" "+expect.Name)
        }

		_ = asset.Cleanup(mgr, useCase.location)

	}
}

GoCover

License

The source code is made available under the terms of the Apache License, Version 2, as stated in the file LICENSE.

Individual files may be made available under their own specific license, all compatible with Apache License, Version 2. Please see individual files for details.

Credits and Acknowledgements

Library Author: Adrian Witas

📚 afs - Awesome Go Library for File Handling

Detailed Description of afs