Support for Blue/Green Deployment

etc/vcl_snippets/deliver.vcl

@@ -3,6 +3,16 @@
         return(deliver);
     }
 
+    if ( fastly.ff.visits_this_service == 0 ) {
+      if ( req.http.Cookie:deploy_version != req.http.request_version && req.http.request_version != table.lookup(magentomodule_config, "current_version", "DEFAULT") ) {
+        set beresp.http.Set-Cookie:deploy_version = req.http.request_version;
+      }
+      # Tell the browser to delete the deploy_version cookie if the requested_version is current version
+      if ( req.http.Cookie:deploy_version != "" &&  req.http.request_version == table.lookup(magentomodule_config, "current_version", DEFAULT ) ) {
+        add beresp.http.Set-Cookie = "deploy_version=DEFAULT; Expires=Wed Jun 01 2022 00:00:00 GMT"; 
+      }
+    }
+
     # Send no cache headers to end users for non-static content created by Magento
     if (resp.http.X-Magento-Tags && fastly.ff.visits_this_service == 0 ) {
         set resp.http.Cache-Control = "no-store, no-cache, must-revalidate, max-age=0";

etc/vcl_snippets/fetch.vcl

@@ -98,14 +98,14 @@
 
         # init surrogate keys
         if (beresp.http.X-Magento-Tags) {
-            set beresp.http.Surrogate-Key = beresp.http.X-Magento-Tags " text";
+            set beresp.http.Surrogate-Key = beresp.http.X-Magento-Tags + " text text-" + table.lookup(magentomodule_config, "current_version", "DEFAULT") ;
         } else {
-            set beresp.http.Surrogate-Key = "text";
+            set beresp.http.Surrogate-Key = "text text-" + table.lookup(magentomodule_config, "current_version", "DEFAULT");
         }
 
         # set surrogate keys by content type if they are image/script or CSS
         if (beresp.http.Content-Type ~ "(image|script|css)") {
-            set beresp.http.Surrogate-Key = re.group.1;
+            set beresp.http.Surrogate-Key = re.group + " " + re.group.1 + "-" + table.lookup(magentomodule_config, "current_version", "DEFAULT");
         }
     }
 

etc/vcl_snippets/hash.vcl

@@ -1,3 +1,6 @@
+    # Add support for versions of the cache depending on the blue/green model. If not specified default to DEFAULT
+    set req.hash += req.http.request_version;
+
     if (req.http.graphql) {
         # GraphQL should cache on X-Magento-Cache-Id if available, which has a bunch of variations so it should be part of the key and not a Vary factor
         if (req.http.X-Magento-Cache-Id) {

etc/vcl_snippets/recv.vcl

@@ -1,3 +1,18 @@
+    if ( table.lookup(magentomodule_config, "current_version", "DEFAULT") != table.lookup(magentomodule_config, "next_version", "DEFAULT") ) {
+      # Check if user has the deploy version
+      if ( req.http.Cookie:deploy_version !=  table.lookup(magentomodule_config, "current_version", "DEFAULT")
+          && req.http.Cookie:deploy_version != table.lookup(magentomodule_config, "next_version", "DEFAULT") ) {
+        # Next Version differs from Current Version. Let's roll out a percentage of traffic
+        if (randombool(std.atoi(table.lookup(magentomodule_config, "rollout_percentage", "0")), 100)) {
+          set req.http.request_version = table.lookup(magentomodule_config, "next_version");
+        }
+    }
+
+    # If request version has not been set by rollout percentage set to current version
+    if ( !req.http.request_version ) {
+      set req.http.request_version = table.lookup(magentomodule_config, "current_version", "DEFAULT");
+    }
+
     # When using Magento tester to test whether your site is configured properly
     # this uses a bypass secret. By default we will use service ID as the bypass secret
     # however user can override this by defining a bypass_secret key in the