Cloud-Init not working

LXD
,
#1

Hi.

I am trying to move my network settings out of the containers (I have custom vlan setup) to organize it in the profiles that I have instead. However cloud-init does not seam to work for some reason.

I have flashed a fresh install of Ubuntu Server 22.04 to a test server where I have tried both LXD 5.0.1 and the latest 5.6. I have tried creating containers from ubuntu:22.04 and images:ubuntu/22.04/cloud, but nothing works. I have also tried using cloud-init.network-config as stated here: cloud-init - LXD documentation as well as user.network-config as stated here: Custom network configuration with cloud-init - LXD documentation. But nothing is changed at all.

I tried using some of the other options, just to see if I could get something to work:

config: 
  cloud-init.user-data: |
    runcmd:
      - [touch, /cloud.init.ran]

But this fails as well. No file is created.

The only way to affect the network from a profile, was to create a mount from the host to /etc/netplan on the container, with a yaml file. This works, but I would much rather have cloud-init work properly.

#2

I just tested using LXD 5.6 and a fresh ubuntu/jammy/cloud image and it works for me using this config:

lxc init images:ubuntu/jammy/cloud c1
lxc config edit c1 #Adds `cloud-init.user-data` key
lxc config show c1
architecture: x86_64
config:
  cloud-init.user-data: |
    #cloud-config
    runcmd:
      - touch /root/cloud.init.ran
  image.architecture: amd64
  image.description: Ubuntu jammy amd64 (20221004_08:30)
  image.os: Ubuntu
  image.release: jammy
  image.serial: "20221004_08:30"
  image.type: squashfs
  image.variant: cloud
  volatile.base_image: 3f53f1fd15686a9a7388cff159e79f87ec3c3435930af9fd529b76923b71ce39
  volatile.cloud-init.instance-id: bf93214b-0af1-4df8-baaa-64d4774bd4da
  volatile.eth0.host_name: veth7b7f1a0f
  volatile.eth0.hwaddr: 00:16:3e:55:47:72
  volatile.idmap.base: "0"
  volatile.idmap.current: '[{"Isuid":true,"Isgid":false,"Hostid":1000000,"Nsid":0,"Maprange":1000000000},{"Isuid":false,"Isgid":true,"Hostid":1000000,"Nsid":0,"Maprange":1000000000}]'
  volatile.idmap.next: '[{"Isuid":true,"Isgid":false,"Hostid":1000000,"Nsid":0,"Maprange":1000000000},{"Isuid":false,"Isgid":true,"Hostid":1000000,"Nsid":0,"Maprange":1000000000}]'
  volatile.last_state.idmap: '[]'
  volatile.last_state.power: RUNNING
  volatile.uuid: 999b441c-29b7-45e7-b87a-1e75bd68638e
devices: {}
ephemeral: false
profiles:
- default
stateful: false
description: ""

lxc start c1
lxc exec c1 -- ls  /root
cloud.init.ran

So make sure that the cloud-init config is set before the first start of the instance (as it only runs on first start) and make sure you’ve got the #cloud-config line in your cloud-init config.

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#3

I don’t get it, #cloud-config is just a comment, why would this be required?

Also, if cloud-init only runs once, then it’s not really useful for my usecase. If I change or add profiles, the configurations for that profile should change along with it. This is no different from my current static netplan setup.

#4

My understanding that in both cases this is how cloud-init is designed, not a LXD specific thing.

You can see this in the cloud-init examples:

https://cloudinit.readthedocs.io/en/latest/topics/examples.html

As for when cloud-init runs, this is up to cloud-init, although I do believe that cloud-init will re-run when it thinks the ID of the instance has changed.

This was added fairly recently (and is in LXD 5.6):

And you can see what triggers an ID change here:

There’s a description of what changes trigger an ID change here:

Which may be sufficient for your use case.

#5

Thanks, this is great info. Also I was not aware that cloud-init was a one-time initialization feature. I thought it ran on every init instance.

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