Configuring FCOS to Use a Static IP Address

As with any custom configuration on FCOS, you can write specific files in the storage node of the Ignition file.

The following snippet shows how to assign the following to eth0:

  • static IP:

  • gateway:

  • DNS:;;

  • DNS search domain:

Example assignment of static IP address
variant: fcos
version: 1.0.0
    - path: /etc/NetworkManager/system-connections/eth0.nmconnection
      mode: 0600
      overwrite: true
        inline: |

          mac-address=<insert MAC address>


During the initramfs portion of the boot process, dracut will attempt to grab a DHCP address. When it times out, Ignition will take over and write the above configuration into the filesystem.

If the interface does not come up correctly on first boot (see tracker issue 358), you have two possible workarounds.

  1. If you configured a username and password in your Ignition configuration, you can log in to the host via the console and issue the following commands to force the static IP to take effect:

    nmcli connection down eth0
    nmcli connection up eth0
  2. If you are not able to access the host via the console, you can reboot the host and the static IP configuration will take effect.