gistfile1.rb

load 'deploy' if respond_to?(:namespace)

# basics
set :branch, "master"
set :scm, "git"
set :deploy_via, :remote_cache

# ssh
set :user, "shared-user"
ssh_options[:forward_agent] = true

namespace :deploy do
  task :default do
    update
  end
end

namespace :symlinks do
  desc "Create symlinks for ignored folders"
  task :make, :roles => :app, :except => { :no_release => true } do
    commands = normal_symlinks.map do |path|
      "rm -rf #{release_path}/#{path} && ln -s #{shared_path}/#{path} #{release_path}/#{path}"
    end

    commands += weird_symlinks.map do |from, to|
      "rm -rf #{release_path}/#{to} && ln -s #{shared_path}/#{from} #{release_path}/#{to}"
    end

    run "cd #{release_path} && #{commands.join(" && ")}"
  end
end

after "deploy:update_code", "symlinks:make"

gistfile2.rb

load "../capistrano/deploy"

# repository
set :application, "capistrano-test"
set :repository,  "git@github.com:company/test.git"

# environments
task :staging do
  role :app, "staging-server"
  set :deploy_to, "/www/capistrano-test/"
end

gistfile3.txt

# GitHub user (jhoyt)
Host github.com
  HostName github.com
  User git
  IdentityFile u:\.ssh\jhoyt
  
# Deployment user (shared-user)
Host staging-server
  HostName staging-server
  User shared-user
  IdentityFile u:\.ssh\shared-user

gistfile4.txt

 ** [staging-server :: err] Error reading response length from authentication socket.
 ** [staging-server :: err] Permission denied (publickey).
 ** [staging-server :: err] fatal:
 ** [staging-server :: err] The remote end hung up unexpectedly
 ** [staging-server :: err]