In addition to configuring different backend types you can also specify other options both through etcd as well as through the Flannel client itself. These options allow you to limit the IP allocation scopes as well as specify a specific interface to use as a Flannel node's external IP endpoint. In this recipe, we'll review the additional configuration options available to you both locally and globally.
We will keep building off the lab in the previous chapter where we configured the host gateway backend. However, the lab topology is going to revert to the previous configuration with Docker hosts docker3 and docker4 being in the 192.168.50.0/24 subnet:
Once you have your hosts configured in this topology, we'll want to wipe out the Flannel configuration. To do that, perform these steps:
On the host running the
etcdservice:sudo systemctl stop etcd sudo rm -rf /var/lib/etcd/default sudo systemctl start etcd
On all the hosts running the Flannel service...