We have just started enabling caching on our Apache 2.2.3 Web Server to take
advantage of the performance increase. We use Apache as a proxy to our back
end Java applications. One of our larger portal applications has had reports
of users logging in and getting other users content. We don't have this
problem when we disable the cache so we are somehow caching user specific
content sometimes. We don't see this with most users in production, and we are
unable to replicate this behavior in test or production at this time.
Does anyone have any ideas what could cause this intermittent caching behavior?
I looked at the Change log and found something that could be a possibility, but
I don't fully understand this bug.
Under 2.2.12 Changes:
*) mod_disk_cache/mod_mem_cache: Fix handling of CacheIgnoreHeaders
directive to correctly remove headers before storing them.
[Lars Eilebrecht]
Could it be possible that CacheIgnoreHeaders is sometimes storing a
"Set-Cookie" header for content when it shouldn't be? If so, would it be
possible that the next request for that content comes with the original
requestors cached "Set-Cookie" header and resets the current users Cookie or
ID. This could then cause the current user to access the original requestors
data since the "Set-Cookie" header might have been accidentally stored in the
cache.
If this could be the cause does anyone know how I could prove this in test?
Here is our current caching configuration using mod_expires, mod_cache, and
mod_disk_cache. We are disabling some areas of the site that use velocity
because we don't want to cache some of the dynamic stuff like sessionVariable
property files for example.
Any help is appreciated! Thank you!
<IfModule mod_cache.c>
<IfModule mod_disk_cache.c>
CacheRoot /opt/apache/cache/
CacheEnable disk /
# FORCE caching for all requests (without Cache-Control: no-cache)
# If Last-Modified header is removed you need to set this to ON to cache
CacheIgnoreNoLastMod On
CacheDisable /business/sessionVariableSetup.vm
CacheDisable /business/education/
CacheDisable /business/partners/
CacheDisable /business/consultants/
CacheDisable /business/home/
CacheIgnoreHeaders Set-Cookie Set-Cookie2
</IfModule>
<IfModule mod_expires.c>
# Add expires headers for images, css & js files
ExpiresActive On
ExpiresByType image/gif A28800
ExpiresByType image/jpeg A28800
ExpiresByType image/png A28800
ExpiresByType text/css A28800
ExpiresByType text/javascript A28800
ExpiresByType application/x-javascript A28800
ExpiresByType application/javascript A28800
ExpiresByType application/ecmascript A28800
ExpiresByType image/x-icon A28800
</IfModule>
</IfModule>
Patrick
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