Implement S3 storage

Signed-off-by: Knut Ahlers <knut@ahlers.me>

storage.go

@@ -33,6 +33,9 @@ func getStorageByURI(uri string) (storage, error) {
 		// NoOp storage: Only logs requests
 		return logStorage{}, nil
 
+	case "s3":
+		return s3StorageFromURI(uri), nil
+
 	default:
 		return nil, fmt.Errorf("Storage scheme %q not defined", u.Scheme)
 	}

storage_s3.go

@@ -0,0 +1,69 @@
+package main
+
+import (
+	"bytes"
+	"io"
+	"io/ioutil"
+	"net/url"
+	"path"
+
+	"github.com/aws/aws-sdk-go/aws"
+	"github.com/aws/aws-sdk-go/aws/awserr"
+	"github.com/aws/aws-sdk-go/aws/session"
+	"github.com/aws/aws-sdk-go/service/s3"
+)
+
+type s3Storage struct {
+	bucket string
+	prefix string
+}
+
+func s3StorageFromURI(uri string) s3Storage {
+	u, _ := url.Parse(uri)
+
+	return s3Storage{
+		bucket: u.Host,
+		prefix: u.Path,
+	}
+}
+
+// WriteFile takes the content of a file and writes it into the underlying
+// storage system.
+func (s s3Storage) WriteFile(filepath string, content io.Reader, contentType string) error {
+	sess := session.Must(session.NewSession())
+	svc := s3.New(sess)
+
+	body, err := ioutil.ReadAll(content)
+	if err != nil {
+		return err
+	}
+
+	_, err = svc.PutObject(&s3.PutObjectInput{
+		Body:        bytes.NewReader(body),
+		Bucket:      aws.String(s.bucket),
+		ContentType: aws.String(contentType),
+		Key:         aws.String(path.Join(s.prefix, filepath)),
+	})
+
+	return err
+}
+
+// ReadFile retrieves a file from the underlying storage, needs to return
+// errFileNotFound when file is not present.
+func (s s3Storage) ReadFile(filepath string) (io.ReadCloser, error) {
+	sess := session.Must(session.NewSession())
+	svc := s3.New(sess)
+
+	res, err := svc.GetObject(&s3.GetObjectInput{
+		Bucket: aws.String(s.bucket),
+		Key:    aws.String(path.Join(s.prefix, filepath)),
+	})
+	if err != nil {
+		if aerr, ok := err.(awserr.Error); ok && aerr.Code() == s3.ErrCodeNoSuchKey {
+			return nil, errFileNotFound
+		}
+		return nil, err
+	}
+
+	return res.Body, nil
+}