MAGETWO-44448: Checkout requests become bottleneck on Varnish 4 due to grace mode

Adding regular expression to allow Varnish bypass shopping cart and checkout requests

Author: Igor Melnikov

app/code/Magento/PageCache/etc/varnish3.vcl

@@ -46,7 +46,12 @@ sub vcl_recv {
     if (req.request != "GET" && req.request != "HEAD") {
         return (pass);
     }
-    
+
+    # Bypass shopping cart and checkout requests
+    if (req.url ~ "/checkout") {
+        return (pass);
+    }
+
     # normalize url in case of leading HTTP scheme and domain
     set req.url = regsub(req.url, "^http[s]?://", "");
 

app/code/Magento/PageCache/etc/varnish4.vcl

@@ -40,6 +40,11 @@ sub vcl_recv {
         return (pass);
     }
 
+    # Bypass shopping cart and checkout requests
+    if (req.url ~ "/checkout") {
+        return (pass);
+    }
+
     # normalize url in case of leading HTTP scheme and domain
     set req.url = regsub(req.url, "^http[s]?://", "");