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Varnish Cache is a web application accelerator also known as a caching HTTP reverse proxy. You install it in front of any server that speaks HTTP and configure it to cache the contents.

Customizing Varnish

By default, varnish comes configured in /etc/varnish/default.vcl to use localhost:8080 as the only backend, default.vcl is called by the default systemd varnish.service file :

Description=Web Application Accelerator

ExecStart=/usr/bin/varnishd -a -f /etc/varnish/default.vcl -T localhost:6082 -s malloc,64M -u nobody -g nobody -F


systemctl enable merely makes a symlink to the default

$ systemctl enable varnish
ln -s '/usr/lib/systemd/system/varnish.service' '/etc/systemd/system/'

Override the defaults in the unit file by using systemctl edit.

$ systemctl edit varnish.service

To override ExecStart use an empty ExecStart line first and then an ExecStart with the new values. Eg.

ExecStart=/usr/bin/varnishd -j unix,user=nobody -F -a :6081 -T localhost:6082 -f /etc/varnish/default.vcl -S /etc/varnish/secret -s malloc,1G

Also, if you change the config file /etc/varnish/default.vcl you'll need to reload varnish:

$ systemctl reload varnish.service

or restart

$ systemctl restart varnish.service

Manual VCL load

If the previous VCL configuration reload failed, try loading the VCL file manually:

  1. Connect to the varnish console:
    $ varnishadm -T localhost:6082
  2. Load the default VCL. Make sure it has at least one backend:
    varnish> vcl.load default /etc/varnish/default.vcl
  3. Make it active:
    varnish> vcl.use default
  4. Start the child proccess (optional):
    varnish> start