Capistrano asks for password when deploying, despite SSH keys

My ssh keys are definitely set up correctly, as I'm never prompted for the password when using ssh. But capistrano still asks for a password when deploying with cap deploy. It doesn't ask for the password when I setup with cap deploy:setup though, strangely enough. It would make the deployment cycle so much smoother without a password prompt.

Specifics: I'm deploying a Sinatra app to a Dreamhost shared account (which uses Passenger). I had followed a tutorial for doing so long back, which worked perfectly back then. Something broke since. I'm using capistrano (2.5.9) and git version 1.6.1.1. Here's my Capfile:

load 'deploy' if respond_to?(:namespace) # cap2 differentiator

set :user, 'ehsanul'
set :domain, 'jellly.com'

default_run_options[:pty] = true

# the rest should be good
set :repository,  "[email protected]:git/jellly.git"
set :deploy_to, "/home/ehsanul/jellly.com"
set :deploy_via, :remote_cache
set :scm, 'git'
set :branch, 'deploy'
set :git_shallow_clone, 1
set :scm_verbose, true
set :use_sudo, false

server domain, :app, :web

namespace :deploy do
  task :migrate do
    run "cd #{current_path}; /usr/bin/rake migrate environment=production"
  end
  task :restart do
    run "touch #{current_path}/tmp/restart.txt"
  end
end

after "deploy", "deploy:migrate"

And here's the output of what happens when I cap deploy, upto the password prompt:

$ cap deploy
  * executing `deploy'
  * executing `deploy:update'
 ** transaction: start
  * executing `deploy:update_code'
    updating the cached checkout on all servers
    executing locally: "git ls-remote [email protected]:git/jellly.git deploy"
/usr/local/bin/git
  * executing "if [ -d /home/ehsanul/jellly.com/shared/cached-copy ]; then cd /home/ehsanul/jellly.com/shared/cached-copy && git fetch  origin && git reset  --hard ea744c77b0b939d5355ba2dc50ef1ec85f918d66 && git clean  -d -x -f; else git clone  --depth 1 [email protected]:git/jellly.git /home/ehsanul/jellly.com/shared/cached-copy && cd /home/ehsanul/jellly.com/shared/cached-copy && git checkout  -b deploy ea744c77b0b939d5355ba2dc50ef1ec85f918d66; fi"
    servers: ["jellly.com"]
    [jellly.com] executing command
 ** [jellly.com :: out] [email protected]'s password:
Password:
 ** [jellly.com :: out]
 ** [jellly.com :: out] remote: Counting objects: 7, done.
remote: Compressing objects: 100% (4/4), done.

What could be broken?

Executing ssh-add ~/.ssh/id_rsa in my local machine fixed the issue for me. It seemed that the ssh command line tool wasn't detecting my identity when called with Capistrano.

The password prompt is because the server you are deploying to is connecting to the git server and needs authentication. Since your local machine (where you are deploying from) already has a valid ssh-key, use that one by enabling forwarding in your Capfile:

set :ssh_options, {:forward_agent => true}

That forwards the authentication from your local machine through when the deployment server tries to connect to your git server.

This is much preferred to putting your private key out on the deployment server!

Another way of getting around the password prompt when the server is ssh'ing back on itself is to tell capistrano not to do so. Thanks to the 'readme' section for Daniel Quimper's capistrano-site5 github repo, we note the following:

set :deploy_via, :copy

Obviously, this works for the case where both the app and git repository are being hosted on the same host. But I guess some of us are doing that :)