Using HTTP Cache

To speed up access to your website, you can set up the HTTP cache. Here are the steps required to do this:

1. Check that your application manages a cache

So that the cache can query the upstream to determine that the targeted resource has not been changed, the application must provide the Etag and/or Last-Modified header.

A response CANNOT be cached if:

1. the Vary header is *,

2. the Content-Type header is not present,

3. the resource Content-Type is not one of the following values:

   • text/html
   • text/xml
   • application/xml
   • application/html+xml
   • application/rss+xml
   • application/rdf+xml
   • application/atom+xml
   • text/javascript ;

4. the Cache-Control header takes one of the following values:

   • private
   • no-store
   • no-cache
   • no-transform ;

5. the Set-Cookie header is present,

6. the Authorization header exists, but Cache-Control takes none of the following values:

   • public
   • must-revalidate
   • proxy-revalidate
   • s-maxage ;

7. The HTTP status code is not one of the following:

   • 200
   • 203
   • 204
   • 206
   • 300
   • 301
   • 404
   • 405
   • 410
   • 414
   • 501

2. Activate the HTTP cache

This is done in Web > Sites > Edit the [site] - ⚙️ > Cache.

Using PURGE

PURGE can be executed in three different ways at alwaysdata:

1. by using the full URL of the resource (e.g. https://test.alwaysdata.net/foo/bar). This will remove the related cache entry and its variations (generated by the Vary header);
2. by adding the X-Cache-Purge-Match: wildcard header and adding a wildcard to your URL (e.g. https://test.alwaysdata.net/*). This will remove all entries matching the URL template;
3. adding the X-Cache-Purge-Match: startswith header and adding a partial path to your URL (e.g. https://test.alwaysdata.net/foo). This will remove all entries matching the URL template (and thus https://test.alwaysdata.net/foo/bar).