As we mentioned earlier, there is currently no direct integration between Flannel and Docker. That being said, we'll need to find a way to get the containers onto the Flannel network without Docker directly knowing that's what's happening. In this recipe, we'll show how this is done, discuss some of the perquisites that led to our current configuration, and see how Flannel handles host-to-host communication.
It is assumed that you're building off the lab described in the previous recipe. In some cases the changes we make may require you to have root-level access to the system.
In the previous recipe, we configured Flannel, but we didn't examine what the Flannel configuration actually did from a network perspective. Let's take a quick look at the configuration of one of our Flannel-enabled hosts to see what's changed:
user@docker4:~$ ip addr …<loopback interface removed for brevity>… 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP...