Bug#850294: apache2: ETags disrupt browser caching when compression is enabled
Package: apache2
Version: 2.4.10-10+deb8u3
Severity: normal
Dear Maintainer,
I observed a different behavior of browser caching between two Apache servers with the same configuration, one uses version 2.2.22-13+deb7u6, the other version 2.4.10-10+deb8u3.
On both servers the deflate, expires, filter and headers modules are enabled.
I found the bugs by testing browser caching for javascript files.
In both configurations there are:
AddOutputFilterByType DEFLATE application/javascript
ExpiresByType application/javascript "access plus 1 year"
For the Apache 2.2 server, in firebug on the second access, there is a 304 HTTP response for all files.
For the Apache 2.4 server, in firebug during the second access, for some javascript file one has a 200 HTTP response and 304 for others.
The difference is due to the size of the files, the smaller ones are not compressed and the caching works.
On the Apache 2.2 server, ETags of compressed files have the form "468166-1f5d-4d64c1c493b5c" as for uncompressed files.
On the Apache 2.4 server, the ETags of the compressed files have the form "bd5-544a79430b300-gzip".
When ETAGs are disabled on the Apache 2.4 server, caching by browsers works well for all files.
Header unset ETag
FileETag none
I do not know if the problem comes from the modules between them or the structure of the ETag.
Regards.
-- Package-specific info:
-- System Information:
Debian Release: 8.0
APT prefers stable-updates
APT policy: (500, 'stable-updates'), (500, 'stable')
Architecture: amd64 (x86_64)
Kernel: Linux 3.16.0-4-amd64 (SMP w/2 CPU cores)
Locale: LANG=fr_FR.UTF-8, LC_CTYPE=fr_FR.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)
Versions of packages apache2 depends on:
ii apache2-bin 2.4.10-10+deb8u3
ii apache2-data 2.4.10-10+deb8u3
ii apache2-utils 2.4.10-9
ii dpkg 1.17.23
ii lsb-base 4.1+Debian13+nmu1
ii mime-support 3.58
ii perl 5.20.2-3+deb8u6
ii procps 2:3.3.9-8
Versions of packages apache2 recommends:
ii ssl-cert 1.0.35
Versions of packages apache2 suggests:
pn apache2-doc <none>
pn apache2-suexec-pristine | apache2-suexec-custom <none>
ii w3m [www-browser] 0.5.3-19
Versions of packages apache2-bin depends on:
ii libapr1 1.5.1-3
ii libaprutil1 1.5.4-1
ii libaprutil1-dbd-sqlite3 1.5.4-1
ii libaprutil1-ldap 1.5.4-1
ii libc6 2.19-18+deb8u3
ii libldap-2.4-2 2.4.40-4
ii liblua5.1-0 5.1.5-7.1
ii libpcre3 2:8.35-3.3
ii libssl1.0.0 1.0.1k-1
ii libxml2 2.9.1+dfsg1-4
ii perl 5.20.2-3+deb8u6
ii zlib1g 1:1.2.8.dfsg-2+b1
Versions of packages apache2-bin suggests:
pn apache2-doc <none>
pn apache2-suexec-pristine | apache2-suexec-custom <none>
ii w3m [www-browser] 0.5.3-19
Versions of packages apache2 is related to:
ii apache2 2.4.10-10+deb8u3
ii apache2-bin 2.4.10-10+deb8u3
-- Configuration Files:
/etc/apache2/apache2.conf changed [not included]
/etc/apache2/conf-available/security.conf changed [not included]
/etc/apache2/mods-available/cache_disk.conf changed [not included]
/etc/apache2/mods-available/deflate.conf changed [not included]
/etc/apache2/mods-available/dir.conf changed [not included]
/etc/apache2/mods-available/mpm_prefork.conf changed [not included]
/etc/apache2/sites-available/000-default.conf changed [not included]
/etc/default/apache2 changed [not included]
/etc/logrotate.d/apache2 changed [not included]
-- no debconf information
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