Add MIME type when uploading to S3

go.mod

@@ -7,6 +7,7 @@ require (
 	github.com/aws/aws-sdk-go v1.44.144
 	github.com/dgraph-io/badger v1.6.2
 	github.com/eduncan911/podcast v1.4.2
+	github.com/gabriel-vasile/mimetype v1.4.10
 	github.com/gilliek/go-opml v1.0.0
 	github.com/golang/mock v1.6.0
 	github.com/hashicorp/go-multierror v1.1.1

go.sum

@@ -36,6 +36,8 @@ github.com/eduncan911/podcast v1.4.2/go.mod h1:mSxiK1z5KeNO0YFaQ3ElJlUZbbDV9dA7R
 github.com/felixge/httpsnoop v1.0.4 h1:NFTV2Zj1bL4mc9sqWACXbQFVBBg2W3GPvqp8/ESS2Wg=
 github.com/felixge/httpsnoop v1.0.4/go.mod h1:m8KPJKqk1gH5J9DgRY2ASl2lWCfGKXixSwevea8zH2U=
 github.com/fsnotify/fsnotify v1.4.7/go.mod h1:jwhsz4b93w/PPRr/qN1Yymfu8t87LnFCMoQvtojpjFo=
+github.com/gabriel-vasile/mimetype v1.4.10 h1:zyueNbySn/z8mJZHLt6IPw0KoZsiQNszIpU+bX4+ZK0=
+github.com/gabriel-vasile/mimetype v1.4.10/go.mod h1:d+9Oxyo1wTzWdyVUPMmXFvp4F9tea18J8ufA774AB3s=
 github.com/gilliek/go-opml v1.0.0 h1:X8xVjtySRXU/x6KvaiXkn7OV3a4DHqxY8Rpv6U/JvCY=
 github.com/gilliek/go-opml v1.0.0/go.mod h1:fOxmtlzyBvUjU6bjpdjyxCGlWz+pgtAHrHf/xRZl3lk=
 github.com/go-logr/logr v1.2.2/go.mod h1:jdQByPbusPIv2/zmleS9BjJVeZ6kBagPoEUsqbVz/1A=

pkg/fs/s3.go

@@ -1,6 +1,7 @@
 package fs
 
 import (
+	"bytes"
 	"context"
 	"io"
 	"net/http"
@@ -13,6 +14,7 @@ import (
 	"github.com/aws/aws-sdk-go/service/s3"
 	"github.com/aws/aws-sdk-go/service/s3/s3iface"
 	"github.com/aws/aws-sdk-go/service/s3/s3manager"
+	"github.com/gabriel-vasile/mimetype"
 	"github.com/pkg/errors"
 	log "github.com/sirupsen/logrus"
 )
@@ -79,12 +81,23 @@ func (s *S3) Create(ctx context.Context, name string, reader io.Reader) (int64,
 	key := s.buildKey(name)
 	logger := log.WithField("key", key)
 
+	// Detect MIME type from the first 512 bytes and then replay them with the rest of the stream.
+	buf := make([]byte, 512)
+	n, err := io.ReadFull(reader, buf)
+	if err != nil && err != io.EOF && err != io.ErrUnexpectedEOF {
+		return 0, errors.Wrap(err, "failed to read file header for MIME detection")
+	}
+	head := buf[:n]
+	m := mimetype.Detect(head)
+	body := io.MultiReader(bytes.NewReader(head), reader)
+
 	logger.Infof("uploading file to %s", s.bucket)
-	r := &readerWithN{Reader: reader}
-	_, err := s.uploader.UploadWithContext(ctx, &s3manager.UploadInput{
-		Bucket: &s.bucket,
-		Key:    &key,
-		Body:   r,
+	r := &readerWithN{Reader: body}
+	_, err = s.uploader.UploadWithContext(ctx, &s3manager.UploadInput{
+		Body:        r,
+		Bucket:      &s.bucket,
+		ContentType: aws.String(m.String()),
+		Key:         &key,
 	})
 	if err != nil {
 		return 0, errors.Wrap(err, "failed to upload file")