Starting a Rails Console with Capistrano 3

When deploying with Capistrano 3, it's often useful to be able to start a rails console without having to ssh into the target host and set it up manually. This can be particularly challenging if you're using rbenv as you have to ensure that rails console is called with suitable environment variables set set to ensure that the rbenv Ruby is used not the system Ruby.

The below snippet works with Capistrano 3 and will attempt to use rbenv_ruby if it is configured in Capistrano, otherwise it will fall back to the default system Ruby.

namespace :rails do
  desc "Start a rails console, for now just with the primary server"
  task :c do
    on roles(:app), primary: true do |role|
      rails_env = fetch(:rails_env)
      execute_remote_command_with_input "#{bundle_cmd_with_rbenv} #{current_path}/script/rails console #{rails_env}"
    end
  end

  def execute_remote_command_with_input(command)
    port = fetch(:port) || 22
    puts "opening a console on: #{host}...."
    cmd = "ssh -l #{fetch(:deploy_user)} #{host} -p #{port} -t 'cd #{deploy_to}/current && #{command}'"
    exec cmd
  end

  def bundle_cmd_with_rbenv
    if fetch(:rbenv_ruby)
      "RBENV_VERSION=#{fetch(:rbenv_ruby)} RBENV_ROOT=#{fetch(:rbenv_path)}  #{File.join(fetch(:rbenv_path), '/bin/rbenv')} exec bundle exec"
    else
      "ruby "
    end
  end
end

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