Sidekiq Capistrano extension to use different sidekiq_processes on different hosts. Disadvantage of using this extension is sequental only commands execution (no parallel execution support).

deploy.rb

require 'sidekiq/capistrano'
load 'config/deploy/extensions/sidekiq' # required to be after require 'sidekiq/capistrano'

set :sidekiq_role, :sidekiq
role :sidekiq, 'server1.com', 'server2.com'

# you may use default syntax – same number of processes at all hosts
# set :sidekiq_processes, 1

# or use hash notation to specify host-dependent number of processes
set :sidekiq_processes, { 'server1.com' => 1, 'server2.com' => 2 }

sidekiq.rb

# place this file into config/deploy/extensions/sidekiq.rb in Rails root folder

namespace :sidekiq do
  def find_hosts_for_task(task, &block)
    find_servers_for_task(current_task).map(&:host)
  end

  def for_each_process(current_host, &block)
    sidekiq_processes = fetch(:sidekiq_processes)
    
    begin
      sidekiq_processes_for_current_server = sidekiq_processes[current_host]
    rescue TypeError
      sidekiq_processes_for_current_server = sidekiq_processes
    end

    sidekiq_processes_for_current_server.times do |idx|
      yield((idx == 0 ? "#{fetch(:sidekiq_pid)}" : "#{fetch(:sidekiq_pid)}-#{idx}"), idx)
    end
  end

  desc "Quiet sidekiq (stop accepting new work)"
  task :quiet, :roles => lambda { fetch(:sidekiq_role) }, :on_no_matching_servers => :continue do
    sidekiqctl_cmd = fetch(:sidekiqctl_cmd)

    find_hosts_for_task(current_task).each do |current_host|
      for_each_process(current_host) do |pid_file, idx|
        run "if [ -d #{current_path} ] && [ -f #{pid_file} ] && kill -0 `cat #{pid_file}`> /dev/null 2>&1; then cd #{current_path} && #{sidekiqctl_cmd} quiet #{pid_file} ; else echo 'Sidekiq is not running'; fi", :hosts => current_host
      end
    end
  end

  desc "Start sidekiq"
  task :start, :roles => lambda { fetch(:sidekiq_role) }, :on_no_matching_servers => :continue do
    rails_env = fetch(:rails_env, "production")
    sidekiq_cmd = fetch(:sidekiq_cmd)

    find_hosts_for_task(current_task).each do |current_host|
      for_each_process(current_host) do |pid_file, idx|
        run "cd #{current_path} ; nohup #{sidekiq_cmd} -e #{rails_env} -C #{current_path}/config/sidekiq.yml -i #{idx} -P #{pid_file} >> #{current_path}/log/sidekiq.log 2>&1 &", :pty => false, :hosts => current_host
      end
    end
  end  

  desc "Stop sidekiq"
  task :stop, :roles => lambda { fetch(:sidekiq_role) }, :on_no_matching_servers => :continue do
    sidekiqctl_cmd = fetch(:sidekiqctl_cmd)
    sidekiq_timeout = fetch(:sidekiq_timeout)

    find_hosts_for_task(current_task).each do |current_host|
      for_each_process(current_host) do |pid_file, idx|
        run "if [ -d #{current_path} ] && [ -f #{pid_file} ] && kill -0 `cat #{pid_file}`> /dev/null 2>&1; then cd #{current_path} && #{sidekiqctl_cmd} stop #{pid_file} #{sidekiq_timeout} ; else echo 'Sidekiq is not running'; fi", :hosts => current_host
      end
    end
  end  
end

@mperham not working with capistrano 2.15.5, unfortunately