We're running Plone 3.3.6 behind Apache 2.2.19 with mod_cache. We've recently noticed that Apache is caching the 206 response to a range request and then serving that partial response when a request for the full resource is made.
What seems to happen:
- some client makes a range request for a resource that is not yet in the cache or is in the cache but has expired
- Apache serves the 206 response correctly
- another client makes a standard request the same resource
- Apache serves the same 206 response to this second client: it should serve the entire response with a 200
This is causing problems with our css on some sites very occasionally
I can replicate this consistently: I wrote a little python script to make a range request.
I don't think we're not doing anything out of the ordinary with our Apache configuration. We're using reverse proxy configuration to serve pages from Plone. The Apache configuration relevant to mod_cache is as follows:
CacheEnable disk / CacheDisable /static CacheDisable /sitemap.xml.gz CacheDisable /robots.txt CacheIgnoreHeaders Set-Cookie UseCanonicalName On RequestHeader edit Accept-Encoding ^.*gzip.*$ gzip early RequestHeader edit Accept-Encoding ^(?!gzip).*$ "" early
The Apache caching guide doesn't include 206 responses in the list of status codes the response "must have" for it to be cached. Is this a bug in Apache or are we doing something wrong in the configuration?