Generate deploy key for Jenkins with Chef and sshkey gem.

chef_sshkey.rb

# Install sshkey gem into chef
chef_gem 'sshkey'

# Base location of ssh key
pkey = node['jenkins']['master']['home'] + '/.ssh/id_rsa'

# Generate a keypair with Ruby
require 'sshkey'
sshkey = SSHKey.generate(
  type: 'RSA',
  comment: "#{node['jenkins']['master']['user']}@#{node['jenkins']['master']['host']}"
)

# Create ~/.ssh directory
directory "#{node['jenkins']['master']['home']}/.ssh" do
  owner node['jenkins']['master']['user']
  group node['jenkins']['master']['group']
  mode 00700
end

# Store private key on disk
template pkey do
  owner node['jenkins']['master']['user']
  group node['jenkins']['master']['group']
  variables(ssh_private_key: sshkey.private_key)
  mode 00600
  action :create_if_missing
end

# Store public key on disk
template "#{pkey}.pub" do
  owner node['jenkins']['master']['user']
  group node['jenkins']['master']['group']
  variables(ssh_public_key: sshkey.ssh_public_key)
  mode 00644
  action :create_if_missing
end

# Save public key
ruby_block 'node-save-pubkey' do
  block do
    node.set_unless['mu_jenkins_pubkey'] = File.read("#{pkey}.pub")
    node.save unless Chef::Config['solo']
  end
end