Update Ubuntu 20.04 default network-config by cloud-config

[Adam Niedzwiecki]

This is a follow-up on the case https://bugs.launchpad.net/cloud-init/+bug/1924922

I cannot update default Ubuntu network-config by writing user-data file in cloud-config.

Attached are logs. Below is a snippet from the cloud-config

#cloud-config
write_files:
  - path: /etc/cloud/cloud.cfg.d/99-disable-network-config.cfg
    permissions: '0644'
    content: |
      network:
        config: disabled
  - path: /etc/netplan/50-cloud-init.yaml
    permissions: '0644'
    content: |
      network:
        version: 2
        ethernets:
          eth0:
            dhcp4: true
            addresses:
              - 192.168.53.3/26
            gateway4: 192.168.53.62
            nameservers:
              addresses:
                - 1.1.1.1
                - 8.8.8.8
runcmd:
  - [sudo, netplan, try]
  - [sudo, netplan, generate]
  - [sudo, netplan, apply]
power_state:
  mode: 'reboot'
  message: 'reboot triggered by cloud-init'

-----

Result is such that the hardcoded network-config ('optional': True, not waiting for DHCP server) is attached/generated with IP as, for an example - 192.168.53.4, not the IP I really want 192.168.53.3. This leads to couple of problems, one as specified in bug/1924922, that ssh_import_id is not working (for the time is not sync up)
Is there a way to overwrite this default with user-data, and not to go to the config partition and manually change it?

[Adam Niedzwiecki (aniecki)]

I also tried to modify this network-config, to delete line

optional: true

runcmd:
  - [
      sudo,
      sed,
      -i,
      '/optional: true/d',
      /boot/firmware/network-config,
    ]

It did deleted the line, yet again I can see this info (with optional: True)

137 2020-04-01 17:23:50,830 - networking.py[DEBUG]: net: all expected physical devices present
    138 2020-04-01 17:23:50,830 - stages.py[DEBUG]: applying net config names for {'version': 2, 'ethernets': {'eth0': {'dhcp4': True, 138 'optional': True}}}
    139 2020-04-01 17:23:50,831 - __init__.py[DEBUG]: no interfaces to rename

----
Please assist, how to change the thing, to optional: False, as the way I applied (deleted the line - as can be verified below) , has no impact

cat /boot/firmware/network-config
# Some additional examples are commented out below

version: 2
ethernets:
  eth0:
    dhcp4: true
#wifis:

[Ryan Harper (raharper)]

Hi Adam,

> Is there a way to overwrite this default with user-data, and not to go to the config partition and manually change it?

No. The network-config on /boot/firmware partition must be edited before you boot the image. Once cloud-init is started, it's too late to modify the network-config (it has already read it off the the partition).

On other cloud platforms, the network config is provided during early boot from the cloud's metadata service. For NoCloud configurations like the rpi image, it has to be done offline.

[Ryan Harper (raharper)]

I'm marking this bug as Invalid. cloud-init is working as expected for NoCloud datasource. Changes to the network-config during execution can't affect cloud-inits behavior during boot with the NoCloud datasource.

[Ryan Harper (raharper)]

This tutorial was helpful to me recently configuring an rpi:

https://ubuntu.com/tutorials/how-to-install-ubuntu-on-your-raspberry-pi#3-wifi-or-ethernet

[James Falcon (falcojr)]

Tracked in Github Issues as https://github.com/canonical/cloud-init/issues/3871