Simple download

download.go

@@ -0,0 +1,23 @@
+package attache
+
+import (
+	"io"
+	"net/http"
+	"path/filepath"
+	"strings"
+)
+
+func (s Server) handleDownload(w http.ResponseWriter, r *http.Request) {
+	fullpath := strings.TrimPrefix(r.URL.RequestURI(), s.GetPrefixPath)
+	objectKey := filepath.Base(fullpath)
+	stream, err := s.Storage.Download(r.Context(), objectKey)
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+	if stream == nil {
+		http.Error(w, fullpath, http.StatusNotFound)
+		return
+	}
+	io.Copy(w, stream)
+}

download_test.go

@@ -0,0 +1,73 @@
+package attache
+
+import (
+	"fmt"
+	"io/ioutil"
+	"net/http"
+	"net/http/httptest"
+	"os"
+	"strconv"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+
+	"golang.org/x/net/context"
+)
+
+func TestHandleDownload(t *testing.T) {
+	testCases := []struct {
+		givenURI         string
+		givenFile        string
+		givenContentType string
+		expectedStatus   int
+		expectedFile     string
+	}{
+		{
+			givenURI:         "/%s",
+			givenFile:        "testdata/transparent.gif",
+			givenContentType: "image/gif",
+			expectedStatus:   http.StatusOK,
+			expectedFile:     "testdata/transparent.gif",
+		},
+		{
+			givenURI:         "/wrong.txt?%s",
+			givenFile:        "testdata/transparent.gif",
+			givenContentType: "image/gif",
+			expectedStatus:   http.StatusNotFound,
+		},
+	}
+
+	for i, tc := range testCases {
+		t.Run(strconv.Itoa(i), func(t *testing.T) {
+			file, err := os.Open(tc.givenFile)
+			if err != nil {
+				t.Fatal(err.Error())
+			}
+			defer file.Close()
+			store := newDummyStore()
+			store.Upload(context.Background(), file, tc.givenContentType)
+
+			r := httptest.NewRequest("GET", fmt.Sprintf(tc.givenURI, store.LastUniqueKey), nil)
+			w := httptest.NewRecorder()
+			s := Server{Storage: store}
+			s.ServeHTTP(w, r)
+
+			result := w.Result()
+			assert.Equal(t, tc.expectedStatus, result.StatusCode)
+			if result.StatusCode != http.StatusOK {
+				return
+			}
+
+			expectedBytes, err := ioutil.ReadFile(tc.expectedFile)
+			if err != nil {
+				t.Fatal(err.Error())
+			}
+			actualBytes, err := ioutil.ReadAll(result.Body)
+			if err != nil {
+				t.Fatal(err.Error())
+			}
+			defer result.Body.Close()
+			assert.Equal(t, expectedBytes, actualBytes)
+		})
+	}
+}

gcloudstore/README.md

@@ -8,8 +8,14 @@ func main() {
 
 	http.Handle(nodego.HTTPTrigger, attache.Server{
 		Storage: gcloudstore.NewStore("your-bucket-name"),
+		GetPrefixPath: "/execute?",
 	})
 
 	nodego.TakeOver()
 }
 ```
+
+NOTE:
+- Google Cloud Function http endpoint matches request path strictly, e.g. `/attache` works but `/attache/thing.jpg` is 404.
+- To workaround that, we need to specify the url as `/attache?thing.jpg` instead
+- But internally our http server sees the prefix as `/execute` ¯\_(ツ)_/¯, so we have to configure `GetPrefixPath: "/execute?"`

gcloudstore/gcloud.go

@@ -1,7 +1,6 @@
 package gcloudstore
 
 import (
-	"bytes"
 	"fmt"
 	"io"
 	"math"
@@ -30,7 +29,7 @@ func NewStore(bucketName string) Store {
 }
 
 // Upload fulfills attache.Store interface
-func (s Store) Upload(ctx context.Context, src *bytes.Reader, fileType string) (string, error) {
+func (s Store) Upload(ctx context.Context, src io.ReadSeeker, fileType string) (string, error) {
 	fileName := filename(fileType)
 
 	client, err := storage.NewClient(ctx)
@@ -49,6 +48,23 @@ func (s Store) Upload(ctx context.Context, src *bytes.Reader, fileType string) (
 	return fileName, nil
 }
 
+// Download fulfills attache.Store interface
+func (s Store) Download(ctx context.Context, filePath string) (io.ReadCloser, error) {
+	client, err := storage.NewClient(ctx)
+	if err != nil {
+		return nil, errors.Wrapf(err, "storage newclient")
+	}
+	body, err := client.Bucket(s.bucketName).Object(filePath).NewReader(ctx)
+	if err == storage.ErrBucketNotExist || err == storage.ErrObjectNotExist {
+		return nil, nil
+	}
+	if err != nil {
+		return nil, errors.Wrapf(err, "storage newreader")
+	}
+
+	return body, nil
+}
+
 func filename(fileType string) string {
 	// Sorts in Reverse Chrono Order
 	key := strconv.FormatInt((math.MaxInt64 - time.Now().UnixNano()), 10)

s3store/s3.go

@@ -1,8 +1,8 @@
 package s3store
 
 import (
-	"bytes"
 	"fmt"
+	"io"
 	"math/rand"
 	"os"
 	"strings"
@@ -11,9 +11,11 @@ import (
 	"golang.org/x/net/context"
 
 	"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"
 	"github.com/oklog/ulid"
+	"github.com/pkg/errors"
 	attache "github.com/winston/attache-lambda"
 )
 
@@ -23,7 +25,7 @@ type Store struct {
 }
 
 // Upload fulfills attache.Store interface
-func (s Store) Upload(ctx context.Context, file *bytes.Reader, fileType string) (string, error) {
+func (s Store) Upload(ctx context.Context, file io.ReadSeeker, fileType string) (string, error) {
 	fileName := filename(fileType)
 	filePath := fmt.Sprintf("https://s3-%s.amazonaws.com/%s/%s", os.Getenv("AWS_REGION"), s.Bucket, fileName)
 
@@ -39,6 +41,27 @@ func (s Store) Upload(ctx context.Context, file *bytes.Reader, fileType string)
 	return filePath, err
 }
 
+// Download fulfills attache.Store interface
+func (s Store) Download(ctx context.Context, filePath string) (io.ReadCloser, error) {
+	svc := s3.New(session.New())
+	result, err := svc.GetObjectWithContext(ctx, &s3.GetObjectInput{
+		Bucket: aws.String(s.Bucket),
+		Key:    &filePath,
+	})
+	if e, ok := err.(awserr.Error); ok {
+		if e.Code() == s3.ErrCodeNoSuchKey ||
+			e.Code() == s3.ErrCodeNoSuchBucket ||
+			e.Code() == s3.ErrCodeNoSuchUpload {
+			return nil, nil
+		}
+	}
+	if err != nil {
+		return nil, errors.Wrapf(err, "get object: %#v", filePath)
+	}
+
+	return result.Body, nil
+}
+
 func filename(fileType string) string {
 	current := time.Now()
 	entropy := rand.New(rand.NewSource(current.UnixNano()))

server.go

@@ -20,7 +20,8 @@ type uploadMeta struct {
 
 // Server handles upload and download
 type Server struct {
-	Storage Store
+	Storage       Store
+	GetPrefixPath string // e.g. `/execute?` we strip away this prefix before we extract `filePath`
 }
 
 func (s Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
@@ -33,6 +34,9 @@ func (s Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		}
 		json.NewEncoder(w).Encode(result)
 
+	case "GET":
+		s.handleDownload(w, r)
+
 	case "OPTIONS":
 		w.Header().Set("Access-Control-Allow-Methods", "POST, PUT, PATCH, OPTIONS")
 

store.go

@@ -1,11 +1,12 @@
 package attache
 
 import (
-	"bytes"
+	"io"
 
 	"golang.org/x/net/context"
 )
 
 type Store interface {
-	Upload(ctx context.Context, file *bytes.Reader, fileType string) (filePath string, err error)
+	Upload(ctx context.Context, file io.ReadSeeker, fileType string) (filePath string, err error)
+	Download(ctx context.Context, filePath string) (io.ReadCloser, error) // should return `nil, nil` for when `filePath` is not found
 }

store_test.go

@@ -5,6 +5,7 @@ package attache
 
 import (
 	"bytes"
+	"io"
 	"io/ioutil"
 
 	"golang.org/x/net/context"
@@ -13,7 +14,8 @@ import (
 )
 
 type dummyStore struct {
-	hash map[string][]byte // default is `nil`
+	hash          map[string][]byte // default is `nil`
+	LastUniqueKey string
 }
 
 func newDummyStore() *dummyStore {
@@ -23,16 +25,27 @@ func newDummyStore() *dummyStore {
 }
 
 // Upload fulfills attache.Store interface
-func (s *dummyStore) Upload(ctx context.Context, file *bytes.Reader, fileType string) (string, error) {
+func (s *dummyStore) Upload(ctx context.Context, file io.ReadSeeker, fileType string) (string, error) {
 	data, err := ioutil.ReadAll(file)
 	if err != nil {
 		return "", err
 	}
 
 	uniqueKey := uuid.NewV4().String()
+	s.LastUniqueKey = uniqueKey
 	s.hash[uniqueKey] = data
 	return uniqueKey, nil
 }
 
+// Download fulfills attache.Store interface
+func (s *dummyStore) Download(ctx context.Context, filePath string) (io.ReadCloser, error) {
+	data, ok := s.hash[filePath]
+	if !ok {
+		return nil, nil
+	}
+
+	return ioutil.NopCloser(bytes.NewReader(data)), nil
+}
+
 // compile-time check that we implement attache.Store interface
 var _ Store = newDummyStore()