Set max-age headers for specific pages, files, or paths

You can configure specific max-age headers for individual pages based on your requirements. For example, a website might consist primarily of static pages, with a news section that updates frequently. In this scenario, cache the static content for one day or longer, and assign a brief cache lifetime of several minutes to the news section.

Modules to control the max-age time

To configure max-age headers for specific pages, install and configure the following modules:

• HTTP Cache Control (D8) module sets the cache lifetime for all HTTP status 404 pages, 302 redirects, and 500-level error pages that Drupal generates.
• Context HTTP Headers (D7) module manages header settings. However, this module depends on Context, which can introduce unwanted overhead to your website.
• Cache Control (D7) module configures max-age headers for individual pages
• Max age (D7) module manages cache lifetimes for each content type.

Changing max-age time for static files

You can modify the Varnish cache for static items such as files, add a custom .htaccess file to the target folders. Do not disable caching completely, instead, modify the cache settings to values appropriate for your website.

For example, when you add a single-line .htaccess file to a folder, external caches such as your browser cache or Varnish cache all files in that directory and any subdirectories for 30 seconds:

# Cache all files on this folder at most for 30 seconds.
Header set Cache-Control "max-age=30, public"

Set this value to 0 to disable caching in this directory. However, Acquia does not recommend this configuration. To disable caching, create an .htaccess file in the directory that contains the files.

To exclude a file type from Varnish, use the following example to prevent caching for CSV or XML files:

# Prevent caching of CSV and XML files
<FilesMatch "\.(csv|xml)$">
Header set Cache-Control "max-age=0, private, no-store, no-cache, must-revalidate"
</FilesMatch>

<FilesMatch "\.(js|mjs)$">
  Header set Cache-Control "max-age=604800, public"
</FilesMatch>

For more information on bypassing the Varnish cache, refer to Bypassing the Varnish cache.

Targeting files by path vs. by filename

The <FilesMatch> and <Files> directives match only against the file name portion of a request and not the full URL path. To apply cache headers only to files in a specific directory path, use one of the following methods:

Option A (recommended): Add a .htaccess File to the Target Subdirectory

Place a separate .htaccess file directly in the target directory, for example, themes/common-assets/pdf-viewer/.htaccess). Directives in this file apply only to that directory and its subdirectories.

# themes/common-assets/pdf-viewer/.htaccess
Header set Cache-Control "max-age=604800, public"

Option B: Use <If> blocks with %{REQUEST_URI}

Cloud Platform supports Apache 2.4 and later, which allows conditional blocks through the <If> directive to test against the full request Uniform Resource Identifier (URI):

<If "%{REQUEST_URI} =~ m|^/themes/common-assets/pdf-viewer/|">
  Header set Cache-Control "max-age=604800, public"
</If>

Option C: Use mod_rewrite conditions with an environment variable

Use RewriteCond to test the request URI and set an environment variable, then apply the header when that variable exists:

RewriteCond %{REQUEST_URI} ^/themes/common-assets/pdf-viewer/
RewriteRule ^ - [E=CACHE_LONG:1]
Header set Cache-Control "max-age=604800, public" env=CACHE_LONG

Using mod_expires to set cache lifetimes

Cloud Platform supports the Apache mod_expires module to set cache lifetimes. Rather than specify an explicit Cache-Control header value, you can use mod_expires to define expiration times relative to the last access or modification time of a file.

Example 1: Cache all files for two weeks after access:

<IfModule mod_expires.c>
  ExpiresActive On
  ExpiresDefault A1209600
</IfModule>

Example 2: Target specific MIME types:

<IfModule mod_expires.c>
  ExpiresActive On
  ExpiresByType application/javascript "access plus 1 week"
  ExpiresByType text/css "access plus 1 week"
</IfModule>

To choose between the two modules:

• Use mod_expires to set expiration times relative to access or modification time by using human-readable syntax.

• Use mod_headers with Header set Cache-Control when you require explicit control over the full Cache-Control header value, such as adding no-store, must-revalidate, or s-maxage.

If both modules set Cache-Control, mod_headers takes precedence

D7: Conditionally overriding max-age time for some Drupal paths

To configure page caching in Drupal 7, navigate to Admin > Configuration > Development > Performance, and enter a value in the Expiration of cached pages field. Alternatively, override this setting by defining the $conf['page_cache_maximum_age'] value in the settings.php file.

For example, the following code snippets update the maximum cache lifetime in seconds. Use the snippet that best suits your website:

# Set max-age for /path/to/page
if (0 === strpos($_SERVER['REQUEST_URI'], '/path/to/page') { 
  $conf['page_cache_maximum_age'] = 300;
}

# Using SCRIPT_URL might be better since it ignores query string
if ($_SERVER['SCRIPT_URL'] == '/path/to/page') {
  $conf['page_cache_maximum_age'] = 300;
}

# Match all /blog* pages
if (isset($_GET['q']) && strpos($_GET['q'], 'blog') === 0) {
  $conf['page_cache_maximum_age'] = 300;
}