capistrano snippet that enables mongrel/thin server switching

deploy.rb

# capistrano deploy.rb snippet that enables
# mongrel/thin (cluster) server switching

# usual capistrano setup such as :
#set :application ... (skipped)

# won't need this anymore - might delete the local .yml config :
#set :mongrel_config, "#{deploy_to}/shared/config/mongrel_cluster.yml"

# special setup for our custom tasks :

set :shared_config_path, "#{shared_path}/config"

set :server_type, :thin # or :mongrel
set :deploy_port, 8000
set :cluster_instances, 5

# helper methods :

def public_configuration_location_for(server)
  "#{current_path}/config/#{server}.yml"
end

def shared_configuration_location_for(server)
  "#{shared_config_path}/#{server}.yml"
end

# Application Server Choices
namespace :mongrel do
  desc "Generate a mongrel configuration file"
  task :build_configuration, :roles => :app do
    config_options = {
      "log_file" => "log/mongrel.log",
      "cwd" => current_path,
      "port" => deploy_port,
      "servers" => cluster_instances,
      "environment" => "production",
      "address" => "127.0.0.1",
      "pid_file" => "tmp/pids/mongrel.pid"
    }.to_yaml
    put config_options, shared_configuration_location_for(:mongrel)
  end

  desc "Links the configuration file"
  task :link_configuration_file, :roles => :app do
    run "ln -nsf #{shared_configuration_location_for(:mongrel)} #{public_configuration_location_for(:mongrel)}"
  end

  desc "Setup Mongrel Cluster After Code Update"
  task :link_global_configuration, :roles => :app do
    run "ln -nsf #{shared_configuration_location_for(:mongrel)} /etc/mongrel_cluster/#{application}.yml"
  end

  %w(start stop restart).each do |action|
    desc "#{action} this app's Mongrel Cluster"
    task action.to_sym, :roles => :app do
      run "mongrel_rails cluster::#{action} -C #{shared_configuration_location_for(:mongrel)}"
    end
  end
end

namespace :thin do 
  desc "Generate a thin configuration file"
  task :build_configuration, :roles => :app do
    config_options = {
      "log" => "log/thin.log",
      "chdir" => current_path,
      "port" => deploy_port,
      "servers" => cluster_instances.to_i,
      "environment" => "production",
      "address" => "127.0.0.1",
      "pid" => "tmp/pids/log.pid"
    }.to_yaml
    put config_options, shared_configuration_location_for(:thin)
  end

  desc "Links the configuration file"
  task :link_configuration_file, :roles => :app do
    run "ln -nsf #{shared_configuration_location_for(:thin)} #{public_configuration_location_for(:thin)}"
  end

  desc "Setup Thin Cluster After Code Update"
  task :link_global_configuration, :roles => :app do
    run "ln -nsf #{shared_configuration_location_for(:thin)} /etc/thin/#{application}.yml"
  end

  %w(start stop restart).each do |action|
    desc "#{action} this app's Thin Cluster"
    task action.to_sym, :roles => :app do
      run "thin #{action} -C #{shared_configuration_location_for(:thin)}"
    end
  end
end

namespace :deploy do
  %w(start stop restart).each do |action|
    desc "#{action} the server"
    task action.to_sym do
      find_and_execute_task("#{server_type}:#{action}")
    end
  end
end

# After Tasks

after "deploy:setup" do
  run "mkdir -p #{shared_config_path}"
end

after "deploy:setup", "#{server_type}:build_configuration"

after "#{server_type}:build_configuration", "#{server_type}:link_global_configuration"

after "deploy:symlink", "#{server_type}:link_configuration_file"