Changed to cache all traffic throught proxy.

nginx.manifest.common.conf

@@ -3,6 +3,6 @@
     add_header X-Docker-Registry-Proxy-Cache-Type "$docker_proxy_request_type";
     proxy_pass https://$targetHost;
     proxy_cache cache;
-    proxy_cache_key   $uri;
+    proxy_cache_key $host$uri;
     proxy_intercept_errors on;
     error_page 301 302 307 = @handle_redirects;