Using the Vary header, the web server can cache several variants of the same page (different languages, compression algorithms, etc.). Kvarn’s built-in cache supports this through configuration, similar to how CORS is configured.

See the docs for an example.

Implementation

When an entry (page) is found in the cache, the contents are checked for matches according to the vary rule. If no match is found, a new response is created and stored.

So for each page cache, there might exist several **Vary**ations of the page. These are served according to a user-defined function, which often reads the accept* headers.