varnish.md

Varnish Consul Template Example

Varnish is an common caching engine that can also act as a proxy. You can read more about the Varnish configuration file syntax in the Varnish documentation.

Backend Router

Here is an example template for rendering a Varnish configuration file with Consul Template:

import directors;
{{range service "consul"}}
backend {{.Name}}_{{.ID}} {
    .host = "{{.Address}}";
    .port = "{{.Port}}";
}{{end}}

sub vcl_init {
  new bar = directors.round_robin();
{{range service "consul"}}
  bar.add_backend({{.Name}}_{{.ID}});{{end}}
}

sub vcl_recv {
  set req.backend_hint = bar.backend();
}

Save this file to disk at a place reachable by the Consul Template process like /tmp/varnish.conf.ctmpl and run Consul Template:

$ consul-template \
  -template="/tmp/varnish.conf.ctmpl:/etc/varnish/varnish.conf"

Here is an example of what the file may render:

import directors;

backend consul_consul {
    .host = "104.131.109.106";
    .port = "8300";"
}

sub vcl_init {
  new bar = directors.round_robin();

  bar.add_backend(consul_consul);
}

sub vcl_recv {
  set req.backend_hint = bar.backend();
}

• For a list of functions, please see the Consul Template README
• For template syntax, please see the golang text/template documentation