MVC4 Bundling Cache Headers

Question

I want to change the cache headers sent from a bundle request. Currently it is varying by User-Agent but I don't want it to, is there a way to change the headers sent by a bundle request?

After a quick look in the System.Web.Optimization assembly I can see the headers get set in Bundle.SetHeaders which is a private static function so I don't think its possible although I would love to be proven wrong.

Answer 1

This isn't something that we currently expose today. We only expose the Cacheability property on the BundleResponse that a IBundleTransform could change. And yes we explicitly set the following things:

                HttpCachePolicyBase cachePolicy = context.HttpContext.Response.Cache;                 cachePolicy.SetCacheability(bundleResponse.Cacheability);                 cachePolicy.SetOmitVaryStar(true);                 cachePolicy.SetExpires(DateTime.Now.AddYears(1));                 cachePolicy.SetValidUntilExpires(true);                 cachePolicy.SetLastModified(DateTime.Now);                 cachePolicy.VaryByHeaders["User-Agent"] = true; 

We have a work item our backlog to open this up and make this more extensible/customizable in the future.

Answer 2

There is a workaround around it as mentioned in janv8000's comment on this response. You need to add the following URL rewrite rule to your web server:

<system.webServer>     <rewrite>         <outboundRules>             <rule name="Cache Bundles" preCondition="IsBundles" patternSyntax="ExactMatch">                 <match serverVariable="RESPONSE_Vary" pattern="User-Agent" />                 <action type="Rewrite" value="Accept-Encoding" />             </rule>             <preConditions>                 <preCondition name="IsBundles" patternSyntax="Wildcard">                     <add input="{URL}" pattern="*/bundles/*" />                 </preCondition>             </preConditions>         </outboundRules>     </rewrite> </system.webServer> 

Obviously you need to pay attention to have all your bundles in your bundles folder or change the IsBundles precondition accordingly.