From 08dc814e98655b1622b4e257ff5dc12fc580eb26 Mon Sep 17 00:00:00 2001
From: DarthSim <darthsim@gmail.com>
Date: Thu, 13 Aug 2020 19:52:35 +0600
Subject: [PATCH] Ability to skip processing of some formats

---
 CHANGELOG.md          |  1 +
 config.go             | 21 +++++++++++++++++++++
 docs/configuration.md | 10 ++++++++++
 processing_handler.go | 15 +++++++++++++++
 4 files changed, 47 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 84069f3c..3585b0bb 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,7 @@
 
 ## [Unreleased]
 ### Added
+- Ability to skip processing of some formats. See [Skip processing](https://docs.imgproxy.net/#/configuration?id=skip-processing).
 - (pro) [video_thumbnail_second](https://docs.imgproxy.net/#/generating_the_url_advanced?id=video-thumbnail-second) processing option.
 - (pro) [background_alpha](https://docs.imgproxy.net/#/generating_the_url_advanced?id=background-alpha) processing option.
 
diff --git a/config.go b/config.go
index baf6f882..552f1996 100644
--- a/config.go
+++ b/config.go
@@ -58,6 +58,23 @@ func boolEnvConfig(b *bool, name string) {
 	}
 }
 
+func imageTypesEnvConfig(it *[]imageType, name string) {
+	*it = []imageType{}
+
+	if env := os.Getenv(name); len(env) > 0 {
+		parts := strings.Split(env, ",")
+
+		for _, p := range parts {
+			pt := strings.TrimSpace(p)
+			if t, ok := imageTypes[pt]; ok {
+				*it = append(*it, t)
+			} else {
+				logWarning("Unknown image format to skip: %s", pt)
+			}
+		}
+	}
+}
+
 func hexEnvConfig(b *[]securityKey, name string) error {
 	var err error
 
@@ -187,6 +204,8 @@ type config struct {
 	EnforceWebp         bool
 	EnableClientHints   bool
 
+	SkipProcessingFormats []imageType
+
 	UseLinearColorspace bool
 	DisableShrinkOnLoad bool
 
@@ -329,6 +348,8 @@ func configure() error {
 	boolEnvConfig(&conf.EnforceWebp, "IMGPROXY_ENFORCE_WEBP")
 	boolEnvConfig(&conf.EnableClientHints, "IMGPROXY_ENABLE_CLIENT_HINTS")
 
+	imageTypesEnvConfig(&conf.SkipProcessingFormats, "IMGPROXY_SKIP_PROCESSING_FORMATS")
+
 	boolEnvConfig(&conf.UseLinearColorspace, "IMGPROXY_USE_LINEAR_COLORSPACE")
 	boolEnvConfig(&conf.DisableShrinkOnLoad, "IMGPROXY_DISABLE_SHRINK_ON_LOAD")
 
diff --git a/docs/configuration.md b/docs/configuration.md
index 8376fbe6..241a276d 100644
--- a/docs/configuration.md
+++ b/docs/configuration.md
@@ -174,6 +174,16 @@ You can set up a fallback image that will be used in case imgproxy can't fetch t
 * `IMGPROXY_FALLBACK_IMAGE_PATH`: path to the locally stored image;
 * `IMGPROXY_FALLBACK_IMAGE_URL`: fallback image URL.
 
+## Skip processing
+
+You can configure imgproxy to skip processing of some formats:
+
+* `IMGPROXY_SKIP_PROCESSING_FORMATS`: list of formats that imgproxy shouldn't process, comma-divided.
+
+**📝Note:** Processing can be skipped only when the requested format is the same as the source format.
+
+**📝Note:** Video thumbnails processing can't be skipped.
+
 ## Presets
 
 Read about imgproxy presets in the [Presets](presets.md) guide.
diff --git a/processing_handler.go b/processing_handler.go
index ca06e583..27686195 100644
--- a/processing_handler.go
+++ b/processing_handler.go
@@ -186,6 +186,21 @@ func handleProcessing(reqID string, rw http.ResponseWriter, r *http.Request) {
 
 	checkTimeout(ctx)
 
+	if len(conf.SkipProcessingFormats) > 0 {
+		imgdata := getImageData(ctx)
+		po := getProcessingOptions(ctx)
+
+		if imgdata.Type == po.Format || po.Format == imageTypeUnknown {
+			for _, f := range conf.SkipProcessingFormats {
+				if f == imgdata.Type {
+					po.Format = imgdata.Type
+					respondWithImage(ctx, reqID, r, rw, imgdata.Data)
+					return
+				}
+			}
+		}
+	}
+
 	imageData, processcancel, err := processImage(ctx)
 	defer processcancel()
 	if err != nil {