Apache mod_disk_cache + mod_expires for 30x to 400x faster puppet file_metadata* requests.

puppetmaster.conf

# Several other articles written about similar setups but
# this seems like the most simple one if you're already using
# Passenger under Apache
#
# http://paperairoplane.net/?p=380
# http://www.masterzen.fr/2010/03/21/more-puppet-offloading/
# 


# Add %D for "The time taken to serve the request, in microseconds."

LogFormat "%h %l %u %t \"%r\" %>s %b %D \"%{Referer}i\" \"%{User-Agent}i\"" puppet

<VirtualHost *:8140>

        CustomLog /var/log/httpd/puppet.log puppet

        <IfModule mod_expires.c>
                <Location /production/file_metadatas/>
                        ExpiresActive On
                        ExpiresDefault "access plus 30 minutes"
                </Location>
        </IfModule>

        <IfModule mod_disk_cache.c>
                CacheEnable disk /production/file_metadata/
                CacheEnable disk /production/file_metadatas/
                CacheRoot "/var/cache/mod_cache"
                CacheDefaultExpire 1800
                CacheIgnoreNoLastMod On # needed because puppet master doesn't add Last-Modifiedu
        </IfModule>

</VirtualHost>

# explanations
#
# Why mod_expire on file_metadatas/?
# file_metadatas/ requests carry query?parameter strings and documents without Expires headers will NOT be cached:
# http://httpd.apache.org/docs/2.2/mod/mod_cache.html#cacheignorequerystring
# "requests with query string parameters are cached separately for each unique query string.
# This is according to RFC 2616/13.9 done only if an expiration time is specified."