Capistrano rolling deploy with haproxy

capistrano_haproxy_rolling_deploy.rb

# Create a map of the deploy server to the haproxy label
server 'A.A.A.A', proxy_label: 'server-01'
server 'B.B.B.B', proxy_label: 'server-02'

# Define our puppet proxy server(s) and role
server 'C.C.C.C', no_release: true, roles: [:proxy]

# We need to override deploy:symlink:linked_dirs
# No way around it - override deploy:symlink:release and rewrite it for rolling deploys
Rake::Task["deploy:symlink:release"].clear_actions
namespace :deploy do
  namespace :symlink do
    task :release do
      on release_roles(:all), :in => :sequence do |release_host|
        unless release_host.properties.proxy_label.to_s.empty?
          on roles(:proxy) do |proxy_host|
            # Put server in maintenance if there is a proxy_label
            execute :haproxyctl, 'disable', 'all', release_host.properties.proxy_label

            # Determine if there are connections to the puppetmaster and block until they finish
            puppet_compiling = true
            while puppet_compiling do
              proxy_stat = capture(:haproxyctl, 'show', 'stat')
              CSV.parse(proxy_stat, headers: true) do |row|
                debug("row[1]: #{row[1]} and proxy_label #{release_host.properties.proxy_label}")
                if row[1] == release_host.properties.proxy_label
                  debug("Current connections for #{release_host.properties.proxy_label}: #{row[4]}")
                  if row[4] == '0'
                    puppet_compiling = false
                  end
                end
              end
              sleep(1)
            end
          end
        end

        # Link new release to current
        tmp_current_path = release_path.parent.join(current_path.basename)
        execute :ln, '-s', release_path, tmp_current_path
        execute :mv, tmp_current_path, current_path.parent

        # Take server out of maintenance
        unless release_host.properties.proxy_label.to_s.empty?
          on roles(:proxy) do |proxy_host|
            execute(:haproxyctl, 'enable', 'all', release_host.properties.proxy_label)
          end
        end
      end
    end
  end
end