unix - Ruby: get local IP (nix)

Question

I need to get my IP (that is DHCP). I use this in my environment.rb:

LOCAL_IP = `ifconfig wlan0`.match(/inet addr:(d*.d*.d*.d*)/)[1] || "localhost"

But is there rubyway or more clean solution?

Answer 1

A server typically has more than one interface, at least one private and one public.

Since all the answers here deal with this simple scenario, a cleaner way is to ask Socket for the current ip_address_list() as in:

require 'socket'

def my_first_private_ipv4
  Socket.ip_address_list.detect{|intf| intf.ipv4_private?}
end

def my_first_public_ipv4
  Socket.ip_address_list.detect{|intf| intf.ipv4? and !intf.ipv4_loopback? and !intf.ipv4_multicast? and !intf.ipv4_private?}
end

Both returns an Addrinfo object, so if you need a string you can use the ip_address() method, as in:

ip= my_first_public_ipv4.ip_address unless my_first_public_ipv4.nil?

You can easily work out the more suitable solution to your case changing Addrinfo methods used to filter the required interface address.