Use project-name to generate IP's for vagrant boxes

README.md

Why

• Static IPs with Vagrant clash easily with other projects
• Dynamic IPs require using port forwards -> port forwards clash with local apps and other projects
• Solution: Provide static IP which are calculated from project name, and then use vagrant-hostupdater to add name -> IP to hosts files for easy use
• Uses 20 first bits from MD5 hash of the name to build IPv4 in Class B private network (smaller addres space than Class A, but rarely used)

vagrant_magic_ip.rb

require 'digest'
require 'ipaddr'

def project_ip(project_name)
  mask = ((1 << 21) - 1)
  low = (172 << 24) | (16 << 16)
  high = Digest::MD5.hexdigest(project_name).to_i(16) & mask

  return IPAddr.new(low | high, Socket::AF_INET).to_s
end

# project_ip("foobar")
# => "172.18.198.63"
# project_ip("projectproject")
# => "172.17.169.109"