publish flannel network info as facts

[igalic]

currently, we deploy this:

file { '/etc/facter/facts.d/flannel.sh':
  ensure  => file,
  mode    => '0700',
  owner   => 'root',
  group   => 'root',
  content => "#!/usr/bin/env bash\n/usr/bin/awk \'{print tolower (\$1)}\' /var/run/flannel/subnet.env",
  require => Class[::flannel]
}

as external fact. This little bash script:

#!/usr/bin/env bash
/usr/bin/awk '{print tolower ($1)}' /var/run/flannel/subnet.env

turns our flannel subnet info:

FLANNEL_NETWORK=172.20.0.0/16
FLANNEL_SUBNET=172.20.9.1/24
FLANNEL_MTU=1450
FLANNEL_IPMASQ=true

into facts:

root@minion0-k8s1:~# facter -p | grep flannel_
flannel_ipmasq => true
flannel_mtu => 1450
flannel_network => 172.20.0.0/16
flannel_subnet => 172.20.9.1/24

I think it would be useful to generalize this.