I have added expires headers to my .htaccess file, they don't really seem to work though.
When checking the result in both Firefox and Chrome (by pressing F12, chosing the Network option and hitting F5 to reload the page), I notice that the rules that I have added in the file are being ignored.
These are the rules, which have been copied from boilerplate:
# ----------------------------------------------------------------------
# | ETags |
# ----------------------------------------------------------------------
# Remove `ETags` as resources are sent with far-future expires headers.
#
# https://developer.yahoo.com/performance/rules.html#etags
# https://tools.ietf.org/html/rfc7232#section-2.3
# `FileETag None` doesn't work in all cases.
<IfModule mod_headers.c>
Header unset ETag
</IfModule>
FileETag None
# ----------------------------------------------------------------------
# | Expires headers |
# ----------------------------------------------------------------------
# Serve resources with far-future expires headers.
#
# (!) If you don't control versioning with filename-based
# cache busting, you should consider lowering the cache times
# to something like one week.
#
# https://httpd.apache.org/docs/current/mod/mod_expires.html
<IfModule mod_expires.c>
ExpiresActive on
ExpiresDefault "access plus 1 month"
# CSS
ExpiresByType text/css "access plus 1 year"
# Data interchange
ExpiresByType application/atom+xml "access plus 1 hour"
ExpiresByType application/rdf+xml "access plus 1 hour"
ExpiresByType application/rss+xml "access plus 1 hour"
ExpiresByType application/json "access plus 0 seconds"
ExpiresByType application/ld+json "access plus 0 seconds"
ExpiresByType application/schema+json "access plus 0 seconds"
ExpiresByType application/vnd.geo+json "access plus 0 seconds"
ExpiresByType application/xml "access plus 0 seconds"
ExpiresByType text/xml "access plus 0 seconds"
# Favicon (cannot be renamed!) and cursor images
ExpiresByType image/vnd.microsoft.icon "access plus 1 week"
ExpiresByType image/x-icon "access plus 1 week"
# HTML
ExpiresByType text/html "access plus 0 seconds"
# JavaScript
ExpiresByType application/javascript "access plus 1 year"
ExpiresByType application/x-javascript "access plus 1 year"
ExpiresByType text/javascript "access plus 1 year"
# Manifest files
ExpiresByType application/manifest+json "access plus 1 week"
ExpiresByType application/x-web-app-manifest+json "access plus 0 seconds"
ExpiresByType text/cache-manifest "access plus 0 seconds"
# Media files
ExpiresByType audio/ogg "access plus 1 month"
ExpiresByType image/bmp "access plus 1 month"
ExpiresByType image/gif "access plus 1 year"
ExpiresByType image/jpeg "access plus 1 year"
ExpiresByType image/png "access plus 1 year"
ExpiresByType image/svg+xml "access plus 1 month"
ExpiresByType image/webp "access plus 1 month"
ExpiresByType video/mp4 "access plus 1 month"
ExpiresByType video/ogg "access plus 1 month"
ExpiresByType video/webm "access plus 1 month"
# Web fonts
# Embedded OpenType (EOT)
ExpiresByType application/vnd.ms-fontobject "access plus 1 month"
ExpiresByType font/eot "access plus 1 month"
# OpenType
ExpiresByType font/opentype "access plus 1 month"
# TrueType
ExpiresByType application/x-font-ttf "access plus 1 month"
# Web Open Font Format (WOFF) 1.0
ExpiresByType application/font-woff "access plus 1 month"
ExpiresByType application/x-font-woff "access plus 1 month"
ExpiresByType font/woff "access plus 1 month"
# Web Open Font Format (WOFF) 2.0
ExpiresByType application/font-woff2 "access plus 1 month"
# Other
ExpiresByType text/x-cross-domain-policy "access plus 1 week"
</IfModule>
And these are the headers shown in the browser. As you can see, components such as scripts and stylesheets expire after one month, while images expire after two months.
Stylesheet headers:
Cache-Control: max-age=2592000, public
Content-Encoding: gzip
Content-Type: text/css
Date: Tue, 21 Jun 2016 16:06:22 GMT
Expires: Thu, 21 Jul 2016 16:06:22 GMT
Script headers:
Cache-Control: max-age=2592000, public
Content-Encoding: gzip
Content-Type: application/javascript
Date: Tue, 21 Jun 2016 16:06:22 GMT
Expires: Thu, 21 Jul 2016 16:06:22 GMT
Image headers:
Cache-Control: max-age=5184000, public
Connection: keep-alive
Date: Tue, 21 Jun 2016 16:10:13 GMT
Expires: Sat, 20 Aug 2016 16:10:13 GMT
Is there something that I can do about this?
First of all, confirm with curl -IL "(URL)" for the exact headers the web server is sending.
Second, ensure you don't have the "Ignore cache" checkbox selected in Chrome.
Third, what does the access log say about these requests, when doing it from curl, Chrome and Firefox?
Edit: the actual answer was to check if the expires module was actually enabled.