Add simple object storage package for s3 and swift

mocks.json

@@ -0,0 +1,12 @@
+{
+  "base_package": "github.com/Scalingo/go-utils",
+  "mocks": [
+    {
+      "interface": "Backend",
+      "src_package": "storage"
+    }, {
+      "interface": "Producer",
+      "src_package": "nsqproducer"
+    }
+  ]
+}

mocks_sig.json

@@ -0,0 +1 @@
+{"github.com/Scalingo/go-utils/nsqproducer.Producer":"33 c7 9b 68 1a 5f 11 fc 4f cb 66 83 92 27 61 b9 c4 ec 87 7b","github.com/Scalingo/go-utils/storage.Backend":"NOFILE"}

storage/backend.go

@@ -0,0 +1,28 @@
+package storage
+
+import (
+	"context"
+	"io"
+)
+
+// BackendMethod represents the name of a Method included in the Backend interface
+type BackendMethod string
+
+const (
+	GetMethod    BackendMethod = "Get"
+	UploadMethod BackendMethod = "Upload"
+	SizeMethod   BackendMethod = "Size"
+	DeleteMethod BackendMethod = "Delete"
+)
+
+// Backend represents something which is able to store files on an object
+// storage service
+type Backend interface {
+	Get(ctx context.Context, path string) (io.ReadCloser, error)
+	Upload(ctx context.Context, file io.Reader, path string) error
+	Size(ctx context.Context, path string) (int64, error)
+	Delete(ctx context.Context, path string) error
+}
+
+var _ Backend = &S3{}
+var _ Backend = &Swift{}

storage/s3.go

@@ -0,0 +1,184 @@
+package storage
+
+import (
+	"context"
+	"io"
+	"time"
+
+	"github.com/Scalingo/go-utils/logger"
+	"github.com/aws/aws-sdk-go-v2/aws"
+	"github.com/aws/aws-sdk-go-v2/aws/awserr"
+	"github.com/aws/aws-sdk-go-v2/aws/defaults"
+	"github.com/aws/aws-sdk-go-v2/aws/endpoints"
+	"github.com/aws/aws-sdk-go-v2/service/s3"
+	"github.com/aws/aws-sdk-go-v2/service/s3/s3manager"
+	"github.com/pkg/errors"
+)
+
+const (
+	NotFoundErrCode = "NotFound"
+)
+
+type S3Client interface {
+	GetObjectRequest(input *s3.GetObjectInput) s3.GetObjectRequest
+	HeadObjectRequest(input *s3.HeadObjectInput) s3.HeadObjectRequest
+	DeleteObjectRequest(input *s3.DeleteObjectInput) s3.DeleteObjectRequest
+}
+
+type S3Config struct {
+	AK       string
+	SK       string
+	Region   string
+	Endpoint string
+	Bucket   string
+}
+
+type RetryPolicy struct {
+	WaitDuration   time.Duration
+	Attempts       int
+	MethodHandlers map[BackendMethod][]string
+}
+
+type S3 struct {
+	cfg         S3Config
+	s3client    S3Client
+	s3uploader  *s3manager.Uploader
+	retryPolicy RetryPolicy
+}
+
+type s3Opt func(s3 *S3)
+
+// WithRetryPolicy is an option to constructor NewS3 to add a Retry Policy
+// impacting GET operations
+func WithRetryPolicy(policy RetryPolicy) s3Opt {
+	return s3Opt(func(s3 *S3) {
+		s3.retryPolicy = policy
+	})
+}
+
+func NewS3(cfg S3Config, opts ...s3Opt) *S3 {
+	s3config := s3Config(cfg)
+	s3 := &S3{
+		cfg: cfg, s3client: s3.New(s3config), s3uploader: s3manager.NewUploader(s3config),
+		retryPolicy: RetryPolicy{
+			WaitDuration: time.Second,
+			Attempts:     3,
+			MethodHandlers: map[BackendMethod][]string{
+				SizeMethod: []string{NotFoundErrCode},
+			},
+		},
+	}
+	for _, opt := range opts {
+		opt(s3)
+	}
+	return s3
+}
+
+func (s *S3) Get(ctx context.Context, path string) (io.ReadCloser, error) {
+	log := logger.Get(ctx)
+	log.WithField("path", path).Info("Get object")
+
+	input := &s3.GetObjectInput{
+		Bucket: &s.cfg.Bucket,
+		Key:    &path,
+	}
+	out, err := s.s3client.GetObjectRequest(input).Send(ctx)
+	if err != nil {
+		return nil, errors.Wrapf(err, "fail to get object %v", path)
+	}
+	return out.Body, nil
+}
+
+func (s *S3) Upload(ctx context.Context, file io.Reader, path string) error {
+	input := &s3manager.UploadInput{
+		Body:   file,
+		Bucket: &s.cfg.Bucket,
+		Key:    &path,
+	}
+	_, err := s.s3uploader.UploadWithContext(ctx, input)
+	if err != nil {
+		return errors.Wrapf(err, "fail to save file to %v", path)
+	}
+
+	return nil
+}
+
+// Size returns the size of the content of the object. A retry mecanism is
+// implemented because of the eventual consistency of S3 backends NotFound
+// error are sometimes returned when the object was just uploaded.
+func (s *S3) Size(ctx context.Context, path string) (int64, error) {
+	var res int64
+	err := s.retryWrapper(ctx, SizeMethod, func(ctx context.Context) error {
+		log := logger.Get(ctx).WithField("key", path)
+		log.Infof("[s3] Size()")
+
+		input := &s3.HeadObjectInput{Bucket: &s.cfg.Bucket, Key: &path}
+		stat, err := s.s3client.HeadObjectRequest(input).Send(ctx)
+		if err != nil {
+			return err
+		}
+		res = *stat.ContentLength
+		return nil
+	})
+
+	if err != nil {
+		return -1, errors.Wrapf(err, "fail to HEAD object '%v'", path)
+	}
+	return res, nil
+}
+
+func (s *S3) Delete(ctx context.Context, path string) error {
+	input := &s3.DeleteObjectInput{Bucket: &s.cfg.Bucket, Key: &path}
+	req := s.s3client.DeleteObjectRequest(input)
+	_, err := req.Send(ctx)
+	if err != nil {
+		return errors.Wrapf(err, "fail to delete object %v", path)
+	}
+
+	return nil
+}
+
+func (s *S3) retryWrapper(ctx context.Context, method BackendMethod, fun func(ctx context.Context) error) error {
+	var err error
+
+	errorCodes := s.retryPolicy.MethodHandlers[method]
+	// no-op is no retry policy on the method
+	if errorCodes == nil {
+		return fun(ctx)
+	}
+	for i := 0; i < s.retryPolicy.Attempts; i++ {
+		log := logger.Get(ctx).WithField("attempt", i+1)
+		ctx := logger.ToCtx(ctx, log)
+		err = fun(ctx)
+		if err == nil {
+			return nil
+		}
+		if aerr, ok := err.(awserr.Error); ok {
+			for _, code := range errorCodes {
+				if aerr.Code() == code {
+					time.Sleep(s.retryPolicy.WaitDuration)
+				}
+			}
+		}
+	}
+	return err
+}
+
+func s3Config(cfg S3Config) aws.Config {
+	credentials := aws.NewStaticCredentialsProvider(cfg.AK, cfg.SK, "")
+	config := aws.Config{
+		Region:      cfg.Region,
+		Handlers:    defaults.Handlers(),
+		HTTPClient:  defaults.HTTPClient(),
+		Credentials: credentials,
+		EndpointResolver: aws.ResolveWithEndpoint(aws.Endpoint{
+			URL:           "https://" + cfg.Endpoint,
+			SigningRegion: cfg.Endpoint,
+		}),
+	}
+	if cfg.Endpoint == "" {
+		config.EndpointResolver = endpoints.NewDefaultResolver()
+	}
+
+	return config
+}