[chef] Get most appropriate IP address from local node

[Geoff Meakin < >]

Hi all, Sorry for the mammoth post!

Obviously I want the same chef code provisioning all my environments, 
including production, dev, test, CI,  etc..

One of the problems I came across is using Vagrant, as it provisions boxes 
differently to AWS/Xen/Knife bootstrapping. I noticed that Vagrant adds an 
extra interface card and IP address via host-only-networking to my dev boxes, 
hence my usual call to node.automatic_attrs['ipaddress'] picks up the 
VirtualBox provisioned one rather than the one I set via Vagrant… frustrating.

For example… I have a bunch of services which need to register themselves 
with DNS. So I'm setting up an APT/YUM server say, and I want the creation of 
the server to register apt.mydomain.com or yum.mydomain.com with the local 
DNS server via dynamic dns. I had this all working on production using 
node.automatic_attrs['ipaddress'].. but with vagrant+virtualbox, this picked 
up the wrong interface ip address.

I solved this by writing a routine "most_relevant_primary_ip_address", which 
resolves to one of any number of interfaces/IP addreses on the local box, and 
checks them via the ruby-ip gem, as to whether they resolve to the correct 
provisioning network, and thus using them. This is also useful in amazon and 
other areas (e.g. IPVS clients) where I have multiple ip addresses going on.

At the moment, I've put the code in a library under networking_basic as 
suggested in the online manual as follows:

networking_basic/libraries/network_utils.rb

require 'ip'

module NetworkUtils
  class Chef::Recipe

    def most_relevant_primary_ip_address

    …. code

    end
  end
end




This seems to be the wrong place for it, the function doesn't really belong 
to a Chef::Recipe.. It needs to be accessible everywhere from each cookbook, 
and needs to run after ohai has done its stuff, and the node object has been 
provisioned.

I would appreciate any pointers as to where else I could put this … and also 
if I've just reinvented the wheel because there's already stuff out there to 
do this.


Thanks!