Cookies and Varnish¶

Varying Varnish caching by cookie value¶

Using the HTTP Vary response header, you can instruct Varnish to store more than one copy of the content from a single URL, based on the values of the cookies specified in the Vary header, as indicated by the following example:

Vary: X-Acquia-Cookie-B

To vary your Varnish caching for all possible combinations of values of multiple cookies, separate the name of each cookie with a comma:

Vary: X-Acquia-Cookie-Key,X-Acquia-Cookie-Value

Session cookies invalidate Varnish caching¶

Content containing Drupal session cookies are never cached, as they contain personalized information that should not be displayed to other users.

Stripping cookie headers from static assets¶

Certain file types managed by Drupal in the modules, themes, files, or libraries directories have incoming cookie headers removed. For more information, see Stripping cookies from static files.

Passing Acquia-provided cookies¶

Acquia provides the following generic cookies for your use in your headers, which you may customize with any value useful to your application:

Passing custom cookies¶

Cookies prefixed with acquia_extract: will be parsed by Cloud Platform. For example, incoming content with a Cookie: acquia_extract:WEBSHOP_CART_ID=1234; header will be parsed into the following headers:

• Cookie: WEBSHOP_CART_ID=1234
• X-Acquia-Cookie-Key: WEBSHOP_CART_ID
• X-Acquia-Cookie-Value: 1234

You can configure your application to provide a Cache-Control: no-cache response header for all requests where the value of X-Acquia-Cookie-Key is WEBSHOP_CART_ID.

Troubleshooting cookie values¶

In PHP, $_COOKIE is populated as an array from the values in an incoming request’s Cookie header. To access this array, your application should parse this array during each Drupal request, such as during hook_init. When troubleshooting your application, code similar to the following examples enables you to review the values stored in your cookie array:

• var_dump($_COOKIE);
• print_r($_COOKIE);

For information about retrieving session cookies when troubleshooting, see the Retrieve a session cookie from a one-time login link Acquia Support Knowledge Base article.