Added config example for Varnish 4.0

Author: thierrymarianne

cookbook/cache/varnish.rst

@@ -57,14 +57,11 @@ Symfony adds automatically:
 .. code-block:: text
 
     sub vcl_fetch {
-        /*
-        Check for ESI acknowledgement
-        and remove Surrogate-Control header
-        */
+        // Check for ESI acknowledgement and remove Surrogate-Control header
         if (beresp.http.Surrogate-Control ~ "ESI/1.0") {
             unset beresp.http.Surrogate-Control;
 
-            // For Varnish >= 3.0
+            // For Varnish >= 3.0, < 4.0
             set beresp.do_esi = true;
             // For Varnish < 3.0
             // esi;
@@ -79,6 +76,33 @@ Symfony adds automatically:
         }
     }
 
+    /**
+     * For Varnish >= 4.0
+     * https://www.varnish-cache.org/docs/4.0/whats-new/upgrading.html#req-not-available-in-vcl-backend-response
+     */
+    sub vcl_backend_response {
+        // Check for ESI acknowledgement and remove Surrogate-Control header
+        if (beresp.http.Surrogate-Control ~ "ESI/1.0") {
+            unset beresp.http.Surrogate-Control;
+
+            // For Varnish >= 3.0 
+            set beresp.do_esi = true;
+            // For Varnish < 3.0 
+            // esi;
+        }   
+        //  By default Varnish ignores Cache-Control: nocache
+        // (https://www.varnish-cache.org/docs/3.0/tutorial/increasing_your_hitrate.html#cache-control),
+        // so in order avoid caching it has to be done explicitly
+        if (beresp.http.Pragma ~ "no-cache" ||
+            beresp.http.Cache-Control ~ "no-cache" ||
+            beresp.http.Cache-Control ~ "private") {
+            // https://www.varnish-cache.org/docs/4.0/whats-new/upgrading.html#hit-for-pass-objects-are-created-using-beresp-uncacheable
+            set beresp.uncacheable = true;
+            set beresp.ttl = 120s;
+            return (deliver);
+        }
+    }
+
 .. caution::
 
     Compression with ESI was not supported in Varnish until version 3.0