Starting docker service in a CentOS image inside OpenStack breaks networking

  centos, docker, networking, openstack

I have a CentOS image inside OpenStack which networks correctly, that is, I can SSH to it.

I need to start docker inside this image, because it is meant to run HyperLedger in the near future. So I had to install the latest docker repo and software, version 19.03.13.

Whenever I do systemctl start docker, I lose network connectivity to the image, and I can only reach it through the OpenStack terminal emulator.

Through it, I see that docker creates two new network interfaces (but it leaves the one that is configured for general networking alone) and also docker creates some iptables rules.

I have tried creating /etc/docker/daemon.json with the contents:

"iptables": false

But this does not solve the issue (it does prevent docker from creating most iptables rules, though).

Does someone knows what is happening, or how to fix it?

Source: Docker Questions