1

I've installed Ubuntu Server 18.04, and instead of the old /etc/network/interfaces, it seems that my network configuration now lives in a series of YAML files in /etc/netplan, of which the only one I actually have is /etc/netplan/50-cloud-init.yaml:

# This file is generated from information provided by
# the datasource.  Changes to it will not persist across an instance.
# To disable cloud-init's network configuration capabilities, write a file
# /etc/cloud/cloud.cfg.d/99-disable-network-config.cfg with the following:
# network: {config: disabled}
network:
    ethernets:
        ens3:
            addresses: []
            dhcp4: true
            dhcp6: true
            nameservers: {}
            optional: true
        ens4:
            addresses: []
            dhcp4: true
            dhcp6: true
            nameservers: {}
            optional: true
    version: 2

That seems to have been generated by cloud-init, from /etc/cloud/cloud.cfg.d/50-curtin-networking.cfg:

network:
  ethernets:
    ens3:
      addresses: []
      dhcp4: true
      dhcp6: true
      nameservers: {}
      optional: true
    ens4:
      addresses: []
      dhcp4: true
      dhcp6: true
      nameservers: {}
      optional: true
  version: 2

What's the right way to edit this configuration and apply the changes to the running machine? The comment in the Netplan file suggested to me that it's ephemeral and generated on reboot by cloud-init, so I should edit cloud-init's config. But even after editing it and rebooting, I don't see any changes to the Netplan file, and I definitely don't know how to apply the cloud-init config changes manually. And upon reading the comment again, now it seems to me that it's talking about changes not persisting across destruction and recreation of the machine, which would seem to go without saying. So clearly I'm misunderstanding something.

So my question is:

  1. Where in the new cloud-init/netplan system am I supposed to be putting manual network configuration?

  2. How do I apply changes I make in /etc/netplan?

  3. How do I apply changes I make in /etc/cloud/cloud.cfg.d?

1

First, you backup the current /etc/netplan/*.yaml file to something like /etc/netplan/*.yaml.BAK.

Then you make any changes you desire to /etc/netplan/*.yaml. Indentation and spacing are VERY important when creating/editing a .yaml file.

FYI: your existing .yaml files should start with:

network:
  version: 2
  renderer: networkd

Then:

sudo netplan -debug generate # generate config files

sudo netplan apply # apply to the current system

reboot # to confirm proper operation

For further examples and configuration guidelines see https://netplan.io/examples

Your Answer

By clicking "Post Your Answer", you acknowledge that you have read our updated terms of service, privacy policy and cookie policy, and that your continued use of the website is subject to these policies.

Not the answer you're looking for? Browse other questions tagged or ask your own question.