Varnish module - install, configure and manage VCL (Ubuntu/CentOS)

This Puppet module installs and configures Varnish.
It also allows to manage Varnish VCL.
Tested on Ubuntu and CentOS.

Class varnish

Installs Varnish.
Provides access to all configuration parameters.
Controls Varnish service.
By default mounts shared memory log directory as tmpfs.

All parameters are low case replica of actual parameters passed to
the Varnish conf file, $class_parameter -> VARNISH_PARAMETER, i.e.

$memlock             -> MEMLOCK
$varnish_vcl_conf    -> VARNISH_VCL_CONF
$varnish_listen_port -> VARNISH_LISTEN_PORT

Exceptions are:
shmlog_dir - location for shmlog
shmlog_tempfs - mounts shmlog directory as tmpfs, (default value: true)
version - passes to puppet type 'package', attribute 'ensure', (default value: present)

At minimum you may want to change a value for default port:
varnish_listen_port => '80'

For more details on parameters, check class varnish.

Usage, class varnish

installs Varnish
allocates for cache 1GB (malloc)
starts it on port 80:

class {'varnish':
  varnish_listen_port => 80,
  varnish_storage_size => '1G',
}

Class varnish::vcl

Manages Varnish VCL configuration.
In most cases Varnish default configuration will run just fine.
The only thing to configure are backends, directors and probes.

VCL applies following restictions:
if you define a probe it must be used
if you define a backend it must be used
if you define a director it must be used

varnish::vcl accepts following parameters:
acls
probes
backends
directors
selectors
conditions
template

While acls, probes, backends and directors are self-explanatory and template is guessable
WTF are selectors and conditions?

You cannot define 2 or more backends/directors and not to use them.
This will result in VCL compilation failure.

Parameter selectors gives access to req.backend inside vcl_recv.
Code:

selectors => [
  { backend => 'cluster2', condition => 'req.url ~ "^/cluster2"' },
  { backend => 'cluster1' },
],

Will result in following VCL configuration to be generated:

if (req.url ~ "^/cluster2") {
  set req.backend = cluster2;
} else {
  set req.backend = cluster1;
}

conditions - TODO.

If modification to Varnish VCL goes further than configuring probes, backends and directors parameter template can be used to point varnish::vcl class at a different template.

NOTE: If you copy existing template and modify it you will still be able to use probes, backends, directors and selectors parameters.

Usage, class varnish::vcl

Simple setup:
1 probe
2 backends
1 director

class { 'varnish::vcl':
  probes => [
    { name => 'health_check', url => "/health_check" },
  ],
  backends => [
    { name => 'server1', host => '192.168.1.1', port => '80', probe => 'health_check' },
    { name => 'server2', host => '192.168.1.2', port => '80', probe => 'health_check' },
  ],
  directors => [
    { name => 'cluster', type => 'round-robin', backends => [ 'server1', 'server2' ] }
  ],
  selectors => [
    { backend => 'cluster' },
  ],
}

Slightly more complex setup:
2 probes
8 backends
2 directors
traffic for URL /cluster2 goes to second director 'cluster2'

class { 'varnish::vcl':
  probes => [
    {
      name      => 'health_check1',
      window    => '8',
      timeout   => '5s',
      threshold => '3',
      interval  => '5s',
      request   => [ "GET /action/healthCheck1 HTTP/1.1", "Host: www.example1.com", "Connection: close" ],
    },
    {
      name      => 'health_check2',
      window    => '8',
      timeout   => '5s',
      threshold => '3',
      interval  => '5s',
      request   => [ "GET /action/healthCheck2 HTTP/1.1", "Host: www.example2.com", "Connection: close" ],
    },
  ],
  backends => [
    { name => 'server1', host => '192.168.1.21', port => '80', probe => 'health_check1' },
    { name => 'server2', host => '192.168.1.22', port => '80', probe => 'health_check1' },
    { name => 'server3', host => '192.168.1.23', port => '80', probe => 'health_check1' },
    { name => 'server4', host => '192.168.1.24', port => '80', probe => 'health_check1' },
    { name => 'server5', host => '192.168.1.25', port => '80', probe => 'health_check1' },
    { name => 'server6', host => '192.168.1.26', port => '80', probe => 'health_check1' },
    { name => 'server7', host => '192.168.1.27', port => '80', probe => 'health_check2' },
    { name => 'server8', host => '192.168.1.28', port => '80', probe => 'health_check2' },
  ],
  directors => [
    {
      name     => 'cluster1',
      backends => [ 'server1', 'server2', 'server3', 'server4', 'server5', 'server6' ],
     },
    {
      name     => 'cluster2',
      backends => [ 'server7', 'server8' ],
    },
  ],
  selectors => [
    { backend => 'cluster2', condition => 'req.url ~ "^/cluster2"' },
    { backend => 'cluster1' },
  ],
}

Tests

For more examples check module tests directory.
NOTE: make sure you don't run tests on Production server.