Merge lp:~tribaal/ubumirror/really-cache-debs-longer into lp:ubumirror

[Chris Glass]

The previous change introducing more aggressive caching for deb files was reverted (probably during a merge), so this reintroduces the 2 weeks timeout for *.deb files.

Since the deb files are versionned (their URL is constant for a given version), there is no reason not to set the cache timeout to "a long time". 2 weeks should be long enough for most of the regular updates to be held in memory for in-between caches, but it could even be set to much longer (or even non-expiring) quite safely.

[lp:~tribaal/ubumirror/really-cache-debs-longer]

76. By Chris Glass on 2014-06-08

Use the expire module instead of just setting headers.

77. By Chris Glass on 2014-06-08

It is actually acceptable to serve stale content in this case - we don't need to force
proxies to refresh debs since they most likely won't change anyway.

78. By Chris Glass on 2014-06-09

Tune the cache behavior a little better.
The expires module sets expire time as well as max-header, no need to specify
it any further.

=== modified file 'apache2-ubuntu-mirror.conf'
--- apache2-ubuntu-mirror.conf	2014-06-08 08:09:28 +0000
+++ apache2-ubuntu-mirror.conf	2014-06-09 06:04:28 +0000
@@ -1,7 +1,7 @@
 # Example apache configuration for the ubuscript mirror.
 # This will serve the default mirror directory on port 80 with a crude virtualhost.
 # Don't forget to allow serving from /srv in /etc/apache2/apache2.conf, and
-# to enable the "headers" module.
+# to enable the "headers" and "expires" modules.
 
 <VirtualHost *:80>
         #ServerAdmin REPLACE_ME_WITH_ADMIN_EMAIL
@@ -17,19 +17,30 @@
 
         # Munge the Cache-Control/Expires response headers to try make
         # transparent proxy servers DTRT.
+        # This is used by the main Ubuntu archives.
         <Files ~ "Release(\.gpg)?|Packages\.(bz2|gz)|Sources\.(bz2|gz)?$">
                 ExpiresActive On
                 ExpiresDefault "modification plus 3300 seconds"
+                # In case a shared cache keeps a copy of the file, explicitely
+                # set the expiry time.
                 Header append Cache-Control "s-maxage=3300"
+                # Proxies (shared caches) must re-obtain the file if it's older
+                # than s-maxage (they can never serve it if it's stale).
                 Header append Cache-Control "proxy-revalidate"
+                # It's ok to serve the same content so several different users.
+                Header append Cache-Control "public"
         </Files>
 
-        # Don't cache HTML files as long (1 hour). This includes the indexes!
-        # This makes caching much more agressive, but may result in updates
-        # being delayed by this max-age value.
-        #<FilesMatch "\.(html|torrent|gz|xz|bz|bz2|dsc|iso|gif|torrent)$">
-        #        Header set Cache-Control "max-age=3600, public, must-revalidate"
-        #</FilesMatch>
+        # Set public cache control and a max age of 2 weeks for the debs and
+        # other files with a versionned URL.
+        <FilesMatch "\.(deb|iso|torrent|zsync)$">
+                ExpiresActive On
+                # Keep the file for two weeks - no matter if it's been modified
+                # recently or not.
+                ExpiresDefault "access plus 1209600 seconds"
+                # It's ok to share the same content between users.
+                Header append Cache-Control "public"
+        </FilesMatch>
 
         # Possible values include: debug, info, notice, warn, error, crit,
         # alert, emerg.