The current iteration of the CDN service does not provide a simple way to manually clear the CDN cache. By default, each asset accessed through a VPN endpoint will be cached with a TTL of 7 days when it is first accessed. The TTL can customized by setting the expires or cache-control headers of the source SOS object.

At 90% of the TTL, if the object has been modified it will be re-downloaded and the CDN cache will be updated with the new version.

If you need more control on your CDN cache, you need to employ one of the following strategies:

  • Use versionning in your file naming scheme
  • Use short TTL

Versioning naming scheme

Using a versioning naming scheme allow to serve different version of your content while ensuring you can show your user new content before the cache expiration.

There are 3 differents strategies that you can employ:

  • using a query string: myfile.txt?v=101
  • adding the version in the filename: myfile.v101.txt
  • using folder naming tree: /v101/myfile.txt

Controling the cache TTL through headers

You can set expires or cache-control on each individual objects to indicate to the CDN provider you want to use as different TTL than the 7 days default.

Cache-Control can for exemple be used to set a 72h TTL:

    Cache-Control: public, max-age=259200

Or you can use the Expires to set a set date at which the content should be considered stale.

    Expires: Wed, 21 Oct 2015 07:28:00 GMT

Detailed documentation about the use of those headers can be found on the MDN documentation: