Firewalld in Atomic Host

cross posted with this Project Atomic blog post


Fedora Atomic Host (and derivatives) will now include the firewalld package in the base OSTree that is tested, delivered, and released every two weeks. Existing users should observe no change as it won’t be enabled by default.

Firewalld in Atomic Host

In the past we have had requests to have firewalld in Atomic Host to enable a better interface into firewall management for administrators and management software. It turns out that if you have lots of rules to manage, or even multiple pieces of software trying to manage different sets of rules on a single system, then iptables becomes a limitation pretty quickly.

Atomic Host users do have the ability to package layer firewalld, but live changes to the host are currently experimental. Since rebooting during system provisioning in certain environments is not desirable, and firewalld is relatively small, the Fedora Atomic Working Group decided to include firewalld in the base OSTree.

In order to not affect existing users the firewalld service will be disabled by default. Existing users should observe no change in behavior. Users who want to use firewalld can enable/start the service and start using it immediately.


So you’re an existing or new user of Atomic Host. What does this mean for you?

I have Atomic Host systems that are already running:

You can rpm-ostree upgrade like normal. The new firewalld package will be delivered as part of updates but won’t be enabled so you should see no change in functionality.

I use the Atomic Host cloud/vagrant images to start new systems:

Nothing will change here. We explicitly disable the firewall in the cloud image kickstarts since cloud environments typically have a higher level firewall mechanism, like security groups.

I install new systems interactively using the ISO:

You should be able to interactively install Atomic Host just fine. firewalld will not be enabled by default.

I install new systems using the ISO with a kickstart file:

In this case if you don’t have a firewall ... line in the kickstart file then you need to add one to say what you want to do. You have three options:

  1. firewall --enable
  2. firewall --disable
  3. firewall --use-system-defaults

The first two options are pretty clear. The last option is a little more unclear. This option was actually added to anaconda / pykickstart to enable us to ask anaconda to leave the system defaults in place so that we could deliver a default in the OSTree and have Anaconda respect that default.

Migrating a system to use firewalld

If you have booted a system and you want to configure it to use firewalld then you can simply enable/start it using systemctl. It’s a good idea to also restart docker, which does some detection on startup to determine what firewall management tool is used. You can do this by either restarting the docker service or rebooting your system so all services restart.

# systemctl enable firewalld
# systemctl start firewalld
# systemctl restart docker

Using firewalld with OpenShift Origin

If you want to use firewalld with OpenShift and you use the OpenShift Ansible installer then you can now set a few variables in your inventory file to tell the installer you want it to use firewalld to manage the firewall. Here are the few variables: