Varnish as HTTP Cache
Overview
Varnish is a HTTP proxy-cache, which works as a reverse proxy between your application and the client. Following rules defined by the user, Varnish will cache the data of an application to reduce the load on its server. We use Varnish 4
Limitations
Varnish is only available on PHP and Go applications. Support for other applications is in discussion.
For more information about it, contact us at support@clever-cloud.com.
Enable Varnish for your application
To enable it, you just have to create a varnish.vcl file in the /clevercloud folder.
This file describes how Varnish caches your applications and how it decides to return a cached resource or not.
The vcl 4.0; and backend section of the `varnish.vcl` configuration file are not necessary as they are already handled by Clever Cloud.
If you have a PHP FTP application or if your `varnish.vcl` file is on an FS Bucket, make sure you redeploy the application for the changes to take effect.
To know how to write your varnish.vcl file, please have a look at the Varnish 4.0 book.
Varnish 3 to 4 migration
If you already have a configuration file written for varnish 3, you can use varnish3to4 to convert it to varnish 4 in order to use it on Clever Cloud.
Example files
We provide some examples of Varnish configuration files that you can
use for your application. Create a /clevercloud folder at the root of your application if it does not exist,
rename the file to varnish.vcl and move it in the /clevercloud folder.