Configuring systemd-networkd on Debian

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By default, Debian uses /etc/network/interfaces file to manage your network interfaces by means of ifup and ifdown commands.

If you’re not happy with it, you can choose to use NetworkManager or systemd networkd. I’m using the latter since it makes managing the interfaces very easily as I’m used to systemd.

If you simply want to have the interface configured as a DHCP client, this is what you need to do:

  1. Backup your existing /etc/network/interfaces 
    mv /etc/network/interfaces /etc/network/interfaces.save
  2. Create a network configuration for systemd-networkd by placing the following content to the file /etc/systemd/network/dhcp.network: 
    [Match]
Name=en*
   
[Network]
DHCP=yes
  3. Then you need to enable systemd-networkd 
    systemctl enable systemd-networkd
  4. Because at this point your network is probably working, the recommendation is that you reboot the computer so it can pick up the configuration by systemd-networkd.

For more complex setups, check out the official docs.

Automating it

Now, of course this is not optimal if manual, so here is the snippet if you need to automate it with Ansible:

- hosts: all
  tasks:
    - name: remove /etc/network/interfaces file
      become: true
      ansible.builtin.file:
        path: /etc/network/interfaces
        state: absent

    - name: configure the network using systemd-networkd
      become: true
      notify:
        - enable systemd-networkd
        - reboot
      ansible.builtin.copy:
        content: |
          [Match]
          Name=en*
          
          [Network]
          DHCP=yes
        dest: /etc/systemd/network/dhcp.network

  handlers:
    - name: enable systemd-networkd
      become: true
      ansible.builtin.systemd: name=systemd-networkd enabled=yes

    - name: reboot
      become: true
      ansible.builtin.reboot: