Is there a way to use capistrano (or similar) to remotely interact with rails console

Question

I\'m loving how capistrano has simplified my deployment workflow, but often times a pushed change will run into issues that I need to log into the server to troubleshoot via the

Answer 1

Not necessarily the best option, but I hacked the following together for this problem in our project:

task :remote_cmd do
  cmd = fetch(:cmd)

  puts `#{current_path}/script/console << EOF\r\n#{cmd}\r\n EOF`
end

To use it, I just use:

cap remote_cmd -s cmd="a = 1; b = 2; puts a+b"

(note: If you use Rails 3, you will have to change script/console above to rails console, however this has not been tested since I don't use Rails 3 on our project yet)

Answer 2

The article http://errtheblog.com/posts/19-streaming-capistrano has a great solution for this. I just made a minor change so that it works in multiple server setup.

  desc "open remote console (only on the last machine from the :app roles)"
  task :console, :roles => :app do
    server = find_servers_for_task(current_task).last
    input = ''

    run "cd #{current_path} && ./script/console #{rails_env}", :hosts => server.host do |channel, stream, data|
      next if data.chomp == input.chomp || data.chomp == ''
      print data
      channel.send_data(input = $stdin.gets) if data =~ /^(>|\?)>/
    end
  end

the terminal you get is not really amazing though. If someone have some improvement that would make CTRL-D and CTRL-H or arrows working, please post it.

Answer 3

This is how i do that without Capistrano: https://github.com/mcasimir/remoting (a deployment tool built on top of rake tasks). I've added a task to the README to open a remote console on the server:

# remote.rake
namespace :remote do

desc "Open rails console on server"
task :console do
  require 'remoting/task'

  remote('console', config.login, :interactive => true) do
    cd config.dest
    source '$HOME/.rvm/scripts/rvm'
    bundle :exec, "rails c production"
  end
end

end

Than i can run

$ rake remote:console

Answer 4

I found pretty nice solution based on https://github.com/codesnik/rails-recipes/blob/master/lib/rails-recipes/console.rb

desc "Remote console" 
task :console, :roles => :app do
  env = stage || "production"
  server = find_servers(:roles => [:app]).first
  run_with_tty server, %W( ./script/rails console #{env} )
end

desc "Remote dbconsole" 
task :dbconsole, :roles => :app do
  env = stage || "production"
  server = find_servers(:roles => [:app]).first
  run_with_tty server, %W( ./script/rails dbconsole #{env} )
end

def run_with_tty(server, cmd)
  # looks like total pizdets
  command = []
  command += %W( ssh -t #{gateway} -l #{self[:gateway_user] || self[:user]} ) if     self[:gateway]
  command += %W( ssh -t )
  command += %W( -p #{server.port}) if server.port
  command += %W( -l #{user} #{server.host} )
  command += %W( cd #{current_path} )
  # have to escape this once if running via double ssh
  command += [self[:gateway] ? '\&\&' : '&&']
  command += Array(cmd)
  system *command
end

Answer 5

cap -T

cap invoke                        # Invoke a single command on the remote ser...
cap shell                         # Begin an interactive Capistrano session.

cap -e invoke

------------------------------------------------------------
cap invoke
------------------------------------------------------------
Invoke a single command on the remote servers. This is useful for performing
one-off commands that may not require a full task to be written for them. Simply
specify the command to execute via the COMMAND environment variable. To execute
the command only on certain roles, specify the ROLES environment variable as a
comma-delimited list of role names. Alternatively, you can specify the HOSTS
environment variable as a comma-delimited list of hostnames to execute the task
on those hosts, explicitly. Lastly, if you want to execute the command via sudo,
specify a non-empty value for the SUDO environment variable.

Sample usage:

  $ cap COMMAND=uptime HOSTS=foo.capistano.test invoke
  $ cap ROLES=app,web SUDO=1 COMMAND="tail -f /var/log/messages" invoke

Answer 6

I really like the "just use the existing tools" approach displayed in this gist. It simply uses the SSH shell command instead of implementing an interactive SSH shell yourself, which may break any time irb changes it's default prompt, you need to switch users or any other crazy thing happens.