swap-setup.rb

require 'fog'
require 'base64'

service = Fog::Compute.new(
  provider: 'rackspace',
  rackspace_username: ENV['RAX_USERNAME'],
  rackspace_api_key: ENV['RAX_API_KEY'],
  rackspace_region: :ord
)

# Adjust these settings based on your needs.
@swapsize = "1048576"
@swappiness = "10"

# See:
# http://www.rackspace.com/knowledge_center/article/create-a-linux-swap-file
enable_swap = Base64.encode64 <<EOF
set -e
dd if=/dev/zero of=/mnt/swapfile bs=1024 count=#{@swapsize}
mkswap /mnt/swapfile
swapon /mnt/swapfile
echo "/mnt/swapfile none swap sw 0 0" >> /etc/fstab
echo "vm.swappiness=#{@swappiness}" >> /etc/sysctl.conf
sysctl vm.swappiness=#{@swappiness}
EOF

# You could also use a keypair.
pubkey = Base64.encode64(File.read("#{ENV['HOME']}/.ssh/id_rsa.pub"))

# Flavor = 1GB standard instance
# Image = Ubuntu 13.10 (Saucy Salamander)
# Adjust for your preference.

puts "creating server."
s = service.servers.create name: 'swappy',
  flavor_id: 'performance1-1', image_id: 'df27d481-63a5-40ca-8920-3d132ed643d9', personality: [
    { path: '/root/enable_swap.sh', contents: enable_swap },
    { path: '/root/.ssh/authorized_keys', contents: pubkey }
  ]

s.wait_for { puts "  progress: #{progress}" ; ready? }

puts "server created."

system "ssh-keyscan #{s.ipv4_address} >> ~/.ssh/known_hosts"
system "ssh root@#{s.ipv4_address} bash /root/enable_swap.sh"

puts "log in with: ssh root@#{s.ipv4_address}"