Re: apache caching not working

[Alexandru Constantinescu <aldavx@xxxxxxxxx>]

dd123 wrote:
> You are right. My apache switched to different runtime user though it started
> as root.
> I changed the dir permission and atleast I can see some contents in the
> cache dir
> But now, I have hit another roadblock:
>
> Basically, I want the images to be served via cache and my images are
> distinguishable through query string 
>
> http://backend-server.abc.com/mcs-stream-war/asset/streamAsset?id=e98a887b-2eb1-456d-ba18-d21a1b0b345th
>
> http://backend-server.abc.com/mcs-stream-war/asset/streamAsset?id=e98a887b-2eb1-456d-ba18-d21a1b0b456ft
>
> http://backend-server.abc.com/mcs-stream-war/asset/streamAsset?id=e98a887b-2eb1-456d-ba18-d21a1b023wert
>
>
> The problem is:  Apache caching solution is ignoring whatever is there in
> the query string after ?.
> It means that whatever value I send in the query string, I am always served
> the first image.
>
> How can force apache caching solution to recognize the query strings and
> store images and its associated query string.
>
>
> Snippet from error_log:
>
>
> [Tue Jan 27 21:43:36 2009] [debug] mod_disk_cache.c(476): disk_cache:
> Recalled cached URL info header
> http://reverse-proxywebserver.abc.com:80/mcs-stream-war/asset/streamAsset?
> [Tue Jan 27 21:43:36 2009] [debug] mod_disk_cache.c(749): disk_cache:
> Recalled headers for URL
> http://reverse-proxywebserver.abc.com:80/mcs-stream-war/asset/streamAsset?
> [Tue Jan 27 21:43:36 2009] [debug] mod_cache.c(282): cache: running
> CACHE_OUT filter
> [Tue Jan 27 21:43:36 2009] [debug] mod_cache.c(296): cache: serving
> /mcs-stream-war/asset/streamAsset
> [Tue Jan 27 21:44:19 2009] [debug] mod_disk_cache.c(476): disk_cache:
> Recalled cached URL info header
> http://reverse-proxywebserver.abc.com:80/mcs-stream-war/asset/streamAsset?
> [Tue Jan 27 21:44:19 2009] [debug] mod_disk_cache.c(749): disk_cache:
> Recalled headers for URL
> http://reverse-proxywebserver.abc.com:80/mcs-stream-war/asset/streamAsset?
>
>
> Alexandru David Constantinescu wrote:
> > dd123 wrote:
> > > I have a webserver servicing the images and url for that webserver looks
> > > like
> > > this:
> > >
> > > http://backend-server.abc.com/mcs-stream-war/asset/streamAsset?id=e98a887b-2eb1-456d-ba18-d21a1b0b06cc
> > >
> > > The above URL is basically an image.
> > >
> > > Now, I want to front this webserver with a reverse proxy caching apache
> > > webserver.  The reverse proxy part is workign good but it looks like the
> > > caching is not working at all. I want to use disk based caching and my
> > > config looks like this:
> > >
> > > ProxyRequests off
> > > ProxyPass        /mcs-stream-war/asset/       
> > > http://backend-server.abc.com/mcs-stream-war/asset/
> > > ProxyPassReverse /mcs-stream-war/asset/       
> > > http://backend-server.abc.com/mcs-stream-war/asset/
> > >
> > >
> > > CacheRoot   /opt/apache2.2.11-mcs-caching/diskcache-store
> > > CacheEnable disk /
> > > CacheDirLevels 2
> > > CacheDirLength 1
> > > CacheMaxFileSize 100000000
> > > CacheIgnoreCacheControl On
> > > CacheIgnoreNoLastMod On
> > > CacheIgnoreNoLastMod On
> > > CacheMaxExpire 604800
> > > CacheIgnoreQueryString On
> > >
> > > Here are my observations and issues:
> > >
> > > 1) when I hit the given reverse proxy apache server with this url:
> > > http://reverse-proxywebserver.abc.com/mcs-stream-war/asset/streamAsset?id=e98a887b-2eb1-456d-ba18-d21a1b0b06cc,
> > > I can see that I am being served the image as the reverse proxy webserver
> > > gets connection to the backend resource 
> > > http://backend-server.abc.com/mcs-stream-war/asset/  and serves the image
> > >
> > > 2) But the caching part is not working at all. Nothing is being created
> > > in
> > > the caching directory at all.
> > >
> > > Here are the debug error messages:
> > >
> > >
> > > [Tue Jan 27 18:55:46 2009] [debug] mod_cache.c(131): Adding CACHE_SAVE
> > > filter for /mcs-stream-war/asset/streamAsset
> > > > not cached. Reason: HTTP Status 304 Not Modified
> > > [Tue Jan 27 18:57:08 2009] [debug] proxy_util.c(2009): proxy: HTTP: has
> > > released connection for (backend-server.abc.com)
> > >
> > >
> > >
> > > Please help me with this. My gut feeling is: I am missing some small
> > > config..
> > Hi
> >
> > Check permissions on your cache folder (apache user must be able to 
> > write in there)
> >
> > alex
> >
> >
> > ---------------------------------------------------------------------
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Hi, again

So , by using CacheIgnoreQueryString On you tell apache to serve from 
cache like ther is no query string (the same url every time). Try to 
disable this option. With this option Off , apache basically will make 
one file/query

Alex

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