Mongrel Cluster Plugin

Tool to help start/stop/restart multiple mongrel servers to use behind a load balancer like Apache 2.2 (mod_proxy_balancer), Lighttpd, Pound, Pen or Balance. This plugin adds an option to specify a number of Mongrel servers to launch, a range of ports, and a configuration file for the cluster. Use “-h” to see command syntax.

Configure cluster and write configuration file:

mongrel_rails cluster::configure

Start cluster:

mongrel_rails cluster::start

Restart cluster:

mongrel_rails cluster::restart

Stop cluster:

mongrel_rails cluster::stop

Capistrano Recipes

Add to config/deploy.rb:

require 'mongrel_cluster/recipes'

Variables:

mongrel_servers: Number of Mongrel servers to start.
mongrel_port: Starting port to bind to.
mongrel_address: Address to bind to.
mongrel_environment: Rails environment to run as.
mongrel_conf: Path to conf file. Defaults to /etc/mongrel_cluster/app_name.conf
mongrel_user: User to run mongrels in cluster as. Unset by default
mongrel_group: Group to run mongrels in cluster as. Unset by default.

On Capistrano 2 you get then get the following tasks:

mongrel:cluster:configure Configure the cluster with variables.
mongrel:cluster:start: Start Mongrel processes on the app server.
mongrel:cluster:stop: Stop the Mongrel processes on the app server.
mongrel:cluster:restart: Restart the Mongrel processes on the app server by starting and stopping mongrel_cluster.
deploy:restart: Calls mongrel:cluster:restart to allow Mongrel to be used with the standard Capistrano deploy task.
deploy:start: Calls mongrel:cluster:start to allow Mongrel to be used with the standard Capistrano deploy task.
deploy:stop: Calls mongrel:cluster:stop to allow Mongrel to be used with the standard Capistrano deploy task.

On Capistrano 1 you get the same tasks, but without the namespace:

configure_mongrel_cluster: Configure the cluster with variables.
start_mongrel_cluster: Start Mongrel processes on the app server.
stop_mongrel_cluster: Stop the Mongrel processes on the app server.
restart_mongrel_cluster: Restart the Mongrel processes on the app server by starting and stopping mongrel_cluster.
restart: Calls restart_mongrel_cluster to allow Mongrel to be used with the standard Capistrano deploy task.
spinner: Calls start_mongrel_cluster to allow Mongrel to be used with the standard Capistrano cold_deploy task.

Starting clusters at boot

  1. Create mongrel_cluster conf directory (/etc/mongrel_cluster).

  2. Assign ownership to your Capistrano user.

  3. Copy the init.d script from this gem’s resouces directory /etc/init.d.

  4. chmod +x /etc/init.d/mongrel_cluster

  5. Add to init.d startup. On RHEL/CentOS use: /sbin/chkconfig –level 345 mongrel_cluster on