my site is a static site and I serve the content from a IIS 8 web server. I used to use Apache and I have the following configuration for cache busting, which I'd like to implement in IIS:
# Extend cache expiry for fingerprinted URLs
RewriteCond %{QUERY_STRING} ^[0-9a-fA-F]{8,}$
RewriteRule ^ - [E=revved:1]
And then I set Cache-Control based on whether the environment variable "revved" is set:
# (For HTTP/1.1 clients)
Header set Cache-Control "max-age=1200" env=!revved
Header set Cache-Control "max-age=31536000" env=revved
My JS and CSS is bundled and I attach the hash to the query string. I do the same for images.
So far what I have been available to do is use the <clientCache /> element and attach cacheControlMode="UseMaxAge and cacheControlMaxAge="00:20:00" to it.
What you can see in the Apache config is that when the "revved" variable is set then the proxy server (CDN) and the client should cache the files for 365 days. Otherwise, it should only cache for 20 minutes. I'd like to have the same behaviour in my web.config.
I read about "Output Caching" in IIS, but from what I understand that is designed for dynamic pages using PHP or ASP.
I would be very grateful, if someone can guide me in the right direction.
I believe that I came up with a solution that is working. I got some hints from this post on MSDN "Change or modify a Response Header value using URL Rewrite".
<outboundRules>
<rule name="ChangeCacheControlHeaderOneYear">
<match serverVariable="RESPONSE_CacheControl" />
<conditions>
<add input="{QUERY_STRING}" pattern="^[0-9a-fA-F]{8,}$" />
</conditions>
<action type="Rewrite" value="max-age=31536000" />
</rule>
<rule name="ChangeCacheControlHeader20Minutes">
<match serverVariable="RESPONSE_CacheControl" />
<conditions>
<add input="{QUERY_STRING}" pattern="^[0-9a-fA-F]{8,}$" negate="true" />
</conditions>
<action type="Rewrite" value="max-age=1200" />
</rule>
</outboundRules>