Follow redirects and cache them properly

Author: ruudk

Makefile

@@ -0,0 +1,21 @@
+clean:
+	rm -rf docker_mirror_cache/*
+
+build:
+	docker build --tag docker-registry-proxy .
+
+start:
+	docker run --rm --name=docker-registry-proxy -it \
+		-p 0.0.0.0:3128:3128 \
+		-p 0.0.0.0:8081:8081 \
+		-e DEBUG=true \
+		-v $(dir $(abspath $(firstword $(MAKEFILE_LIST))))/docker_mirror_cache:/docker_mirror_cache \
+		-v $(dir $(abspath $(firstword $(MAKEFILE_LIST))))/docker_mirror_certs:/ca \
+		docker-registry-proxy
+
+stop:
+	docker stop docker-registry-proxy
+
+test: build start
+
+.INTERMEDIATE: clean stop

nginx.conf

@@ -198,8 +198,8 @@ echo "Docker configured with HTTPS_PROXY=$scheme://$http_host/"
         proxy_cache_lock on;
         proxy_cache_lock_timeout 880s;
 
-        # Cache all 200, 301, 302, and 307 (emitted by private registries) for 60 days.
-        proxy_cache_valid 200 301 302 307 60d;
+        # Cache all 200, 206 for 60 days.
+        proxy_cache_valid 200 206 60d;
 
         # Some extra settings to maximize cache hits and efficiency
         proxy_force_ranges on;
@@ -225,47 +225,28 @@ echo "Docker configured with HTTPS_PROXY=$scheme://$http_host/"
             return 405 "docker-registry-proxy: docker is trying to use v1 API. Either the image does not exist upstream, or you need to configure docker-registry-proxy to authenticate against $host";
         }
 
-
         # for the /v2/..../blobs/.... URIs, do cache, and treat redirects.
         location ~ ^/v2/(.*)/blobs/ {
             proxy_pass https://$targetHost;
             proxy_cache cache;
-            add_header X-Docker-Caching-Proxy-Debug-Cache "yes:blobs";
-
-            # Handling of redirects.
-            # Many registries (eg, quay.io, or k8s.gcr.io) emit a Location redirect
-            # pointing to something like cloudfront, or google storage.
-            # We hack into the response, extracting the host and URI parts, injecting them into a URL that points back to us
-            # That gives us a chance to intercept and cache those, which are the actual multi-megabyte blobs we originally wanted to cache.
-            # We to it twice, one for http and another for https.
-            proxy_redirect ~^https://([^:/]+)(/.+)$ https://docker.caching.proxy.internal/forcecachesecure/$1/originalwas$2;
-            proxy_redirect ~^http://([^:/]+)(/.+)$ http://docker.caching.proxy.internal/forcecacheinsecure/$1/originalwas$2;
+            proxy_cache_key   $uri;
+            proxy_intercept_errors on;
+            error_page 301 302 307 = @handle_redirects;
         }
 
+        location @handle_redirects {
+            #store the current state of the world so we can reuse it in a minute
+            # We need to capture these values now, because as soon as we invoke
+            # the proxy_* directives, these will disappear
+            set $original_uri $uri;
+            set $orig_loc $upstream_http_location;
 
-        # handling for the redirect case explained above, with https.
-        # The $realHost and $realPath variables come from a map defined at the top of this file.
-        location /forcecachesecure {
-            proxy_pass https://$realHost$realPath;
-            proxy_cache cache;
-
-            # Change the cache key, so that we can cache signed S3 requests and such. Only host and path are considered.
-            proxy_cache_key $proxy_host$uri;
-
-            add_header X-Docker-Caching-Proxy-Debug-Cache "yes:forcecachesecure";
-
-        }
-
-        # handling for the redirect case explained above, with http.
-        # The $realHost and $realPath variables come from a map defined at the top of this file.
-        location /forcecacheinsecure {
-            proxy_pass http://$realHost$realPath;
+            # nginx goes to fetch the value from the upstream Location header
+            proxy_pass $orig_loc;
             proxy_cache cache;
-
-            # Change the cache key, so that we can cache signed S3 requests and such. Only host and path are considered.
-            proxy_cache_key $proxy_host$uri;
-
-            add_header X-Docker-Caching-Proxy-Debug-Cache "yes:forcecacheinsecure";
+            # But we store the result with the cache key of the original request URI
+            # so that future clients don't need to follow the redirect too
+            proxy_cache_key $original_uri;
         }
 
         # by default, dont cache anything.
@@ -274,6 +255,5 @@ echo "Docker configured with HTTPS_PROXY=$scheme://$http_host/"
             proxy_cache off;
             add_header X-Docker-Caching-Proxy-Debug-Cache "no:default";
         }
-
     }
 }