varnish 4: force cache all

note: for varnish 4.x

sub vcl_backend_response {  
     # client browser and server cache  
     # Force cache: remove expires, Cache-control & Pragma header coming from the backend  
     if (beresp.http.Cache-Control ~ "(no-cache|private)" || beresp.http.Pragma ~ "no-cache") {  
         unset beresp.http.Expires;  
         unset beresp.http.Cache-Control;  
         unset beresp.http.Pragma;  
         # Marker for vcl_deliver to reset Age: /  
         set beresp.http.magicmarker = "1";  
         # Leveraging browser, cache set the clients TTL on this object /  
         set beresp.http.Cache-Control = "public, max-age=60";  
         # cache set the clients TTL on this object /  
         set beresp.ttl = 1m;  
         # Allow stale content, in case the backend goes down.  
         # make Varnish keep all objects for 6 hours beyond their TTL  
         set beresp.grace = 6h;  
         return (deliver);  
     }  
 }  
 sub vcl_deliver {  
     # Called before a cached object is delivered to the client.  
     if (resp.http.magicmarker) {  
     unset resp.http.magicmarker;  
     # By definition we have a fresh object  
     set resp.http.Age = "0";  
     }  
     if (obj.hits > 0) { # Add debug header to see if it's a HIT/MISS and the number of hits, disable when not needed  
     set resp.http.X-Cache = "HIT";  
     } else {  
     set resp.http.X-Cache = "MISS";  
     }  
     # Please note that obj.hits behaviour changed in 4.0, now it counts per objecthead, not per object  
     # and obj.hits may not be reset in some cases where bans are in use. See bug 1492 for details.  
     # So take hits with a grain of salt  
     set resp.http.X-Cache-Hits = obj.hits;  
     # Set Varnish server name  
     set resp.http.X-Served-By = server.hostname;  
     # Remove some headers: PHP version  
     unset resp.http.X-Powered-By;  
     # Remove some headers: Apache version & OS  
     unset resp.http.Server;  
     unset resp.http.X-Varnish;  
     unset resp.http.Via;  
     unset resp.http.Link;  
     unset resp.http.X-Generator;  
     return (deliver);  
 }