memcached module for Puppet

Manage memcached via Puppet

How to use

Starting with version 3.0.0, memcached will be listening on 127.0.0.1 only.
This should make setups more secure (e.g. if there are no firewall rules in place).

For the old behaviour, you need to set listen to '0.0.0.0'.

Use roughly 90% of memory

    class { 'memcached': }

Set a fixed memory limit in MB

    class { 'memcached':
      max_memory => 2048
    }

Use 12% of available memory

    class { 'memcached':
      max_memory => '12%'
    }

Install multiple memcached instances

the multiinstance support uses a systemd instance unit file. This will be placed at /etc/systemd/system/[email protected]. It allows us to manage multiple instances via the same unit file. To start a simple instance, you only need to know the desired TCP port:

memcached::instance{'11222':}

that's it! It will bind to localhost and listen to TCP port 11222. You might want to tune the systemd limits, for example the number of file descriptors (LimitNOFILE) or the number of processes (LimitNPROC):

memcached::instance{'11222':
  limits => {
    'LimitNOFILE' => 8192,
    'LimitNPROC'  => 16384,
  }
}

All systemd limits are documented in the systemd documentation.

Another usecase. Let's assume your name is Eric and you want to change the actual memcached parameters, for example to bind it to every interface:

memcached::instance{'11222':
  override_content => "[Service]\nEnvironment='LISTEN=-l 0.0.0.0'",
}

Maybe Eric also wants to override the cache size (the unit is MB):

memcached::instance{'11222':
  override_content => "[Service]\nEnvironment=CACHESIZE=4096\n",
}

last but not least, Eric might also want to override the maximum amount of connections (the default is 1024):

memcached::instance{'11222':
  override_content => "[Service]\nEnvironment=MAXCONN=4096\n",
}

Now Eric wants to use all those three settings at the same time:

memcached::instance{'11222':
  override_content => "[Service]\nEnvironment=MAXCONN=4096\nEnvironment=CACHESIZE=4096\nEnvironment='LISTEN=-l 0.0.0.0'\n",
}

Instead of passing a long string with multiple \n, Eric can also put the content in a file and provide that:

memcached::instance{'11222':
  override_source => "${module_name}/memcached_11222_override.conf\n",
}