feature: add default fallback image when failed to load from storage (#6

) (#7)


---------

Co-authored-by: Agung Hariadi Tedja <[email protected]>

README.md

@@ -614,6 +614,8 @@ Usage of imagor:
         imagor disable /params endpoint
   -imagor-disable-error-body
         imagor disable response body on error
+  -imagor-image-error-fallback
+        imagor image fallback in base64 when error loading image from storage
 
   -server-address string
         Server address

blob.go

@@ -3,6 +3,7 @@ package imagor
 import (
 	"bytes"
 	"encoding/json"
+	"errors"
 	"github.com/kumparan/imagor/fanoutreader"
 	"github.com/kumparan/imagor/seekstream"
 	"io"
@@ -293,7 +294,7 @@ func (b *Blob) doInit() {
 		b.blobType = BlobTypeEmpty
 	}
 	if err != nil &&
-		err != io.ErrUnexpectedEOF &&
+		!errors.Is(err, io.ErrUnexpectedEOF) &&
 		err != io.EOF {
 		if b.err == nil {
 			b.err = err

config/config.go

@@ -66,6 +66,7 @@ func NewImagor(
 			"Check modified time of result image against the source image. This eliminates stale result but require more lookups")
 		imagorDisableErrorBody       = fs.Bool("imagor-disable-error-body", false, "imagor disable response body on error")
 		imagorDisableParamsEndpoint  = fs.Bool("imagor-disable-params-endpoint", false, "imagor disable /params endpoint")
+		imagorImageErrorFallback     = fs.String("imagor-image-error-fallback", "", "imagor image error fallback when failed to load from storage, in base64")
 		imagorSignerType             = fs.String("imagor-signer-type", "sha1", "imagor URL signature hasher type: sha1, sha256, sha512")
 		imagorSignerTruncate         = fs.Int("imagor-signer-truncate", 0, "imagor URL signature truncate at length")
 		imagorStoragePathStyle       = fs.String("imagor-storage-path-style", "original", "imagor storage path style: original, digest")
@@ -122,6 +123,7 @@ func NewImagor(
 		imagor.WithUnsafe(*imagorUnsafe),
 		imagor.WithLogger(logger),
 		imagor.WithDebug(isDebug),
+		imagor.WithImageErrorFallback(*imagorImageErrorFallback),
 	)...)
 }
 

config/config_test.go

@@ -41,6 +41,8 @@ func TestDefault(t *testing.T) {
 }
 
 func TestBasic(t *testing.T) {
+	placeholderData := `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`
+
 	srv := CreateServer([]string{
 		"-debug",
 		"-port", "2345",
@@ -59,6 +61,7 @@ func TestBasic(t *testing.T) {
 		"-imagor-base-params", "filters:watermark(example.jpg)",
 		"-imagor-cache-header-ttl", "169h",
 		"-imagor-cache-header-swr", "167h",
+		"-imagor-image-error-fallback", placeholderData,
 		"-http-loader-insecure-skip-verify-transport",
 		"-http-loader-override-response-headers", "cache-control,content-type",
 		"-http-loader-base-url", "https://www.example.com/foo.org",
@@ -82,6 +85,7 @@ func TestBasic(t *testing.T) {
 	assert.Equal(t, "filters:watermark(example.jpg)/", app.BaseParams)
 	assert.Equal(t, time.Hour*169, app.CacheHeaderTTL)
 	assert.Equal(t, time.Hour*167, app.CacheHeaderSWR)
+	assert.Equal(t, placeholderData, app.ImageErrorFallback)
 
 	httpLoader := app.Loaders[0].(*httploader.HTTPLoader)
 	assert.True(t, httpLoader.Transport.(*http.Transport).TLSClientConfig.InsecureSkipVerify)

imagor.go

@@ -89,6 +89,7 @@ type Imagor struct {
 	BaseParams             string
 	Logger                 *zap.Logger
 	Debug                  bool
+	ImageErrorFallback     string
 
 	g          singleflight.Group
 	sema       *semaphore.Weighted
@@ -171,7 +172,7 @@ func (app *Imagor) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 	blob, err := checkBlob(app.Do(r, p))
-	if err == ErrInvalid || err == ErrSignatureMismatch {
+	if errors.Is(err, ErrInvalid) || errors.Is(err, ErrSignatureMismatch) {
 		if path2, e := url.QueryUnescape(path); e == nil {
 			path = path2
 			p = imagorpath.Parse(path)
@@ -521,11 +522,25 @@ func fromStorages(
 
 func (app *Imagor) loadStorage(r *http.Request, key string, isBase64 bool) (blob *Blob, shouldSave bool, err error) {
 	r = app.requestWithLoadContext(r)
+
 	var origin Storage
 	blob, origin, err = app.fromStoragesAndLoaders(r, app.Storages, app.Loaders, key, isBase64)
 	if !isBlobEmpty(blob) && origin == nil &&
 		key != "" && err == nil && len(app.Storages) > 0 {
 		shouldSave = true
+		app.Logger.Error("fail to load from storage", zap.String("key", key), zap.Error(err))
+	}
+
+	if (err != nil || isBlobEmpty(blob)) && len(app.ImageErrorFallback) > 0 {
+		data, errDecode := base64.StdEncoding.DecodeString(app.ImageErrorFallback)
+		if errDecode != nil {
+			app.Logger.Error("failed to decode base64", zap.Error(errDecode))
+		}
+
+		mimeType := http.DetectContentType(data)
+		blob = NewBlobFromBytes(data)
+		blob.SetContentType(mimeType)
+		err = nil // reset error
 	}
 	return
 }

imagor_test.go

@@ -588,6 +588,26 @@ func TestParams(t *testing.T) {
 	assert.Empty(t, w.Body.String())
 }
 
+func TestUseFallbackImageWhenLoadError(t *testing.T) {
+	loader := loaderFunc(func(r *http.Request, image string) (*Blob, error) {
+		return NewBlobFromFile("./non-exists-path"), nil
+	})
+	placeholderData := `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`
+
+	app := New(
+		WithDebug(true),
+		WithLogger(zap.NewExample()),
+		WithUnsafe(true),
+		WithLoaders(loader),
+		WithImageErrorFallback(placeholderData))
+
+	r := httptest.NewRequest(
+		http.MethodGet, "https://example.com/unsafe/foobar", nil)
+	w := httptest.NewRecorder()
+	app.ServeHTTP(w, r)
+	assert.Equal(t, 200, w.Code)
+}
+
 var clock time.Time
 
 type mapStore struct {

option.go

@@ -227,3 +227,10 @@ func WithSigner(signer imagorpath.Signer) Option {
 		}
 	}
 }
+
+// WithImageErrorFallback with image error fallback option
+func WithImageErrorFallback(base64Image string) Option {
+	return func(app *Imagor) {
+		app.ImageErrorFallback = base64Image
+	}
+}