Hostname changes after every reboot with OpenNebula

[Corey Melanson]

When using the OpenNebula datasource (Ubuntu 16.04.4, cloud-init 18.2-4-g05926e48-0ubuntu1~16.04.2) the hostname switches after every reboot between the one defined by the OpenNebula HOSTNAME context variable and one based on the IP address (eg ip-10-22-33-44).

I took some time to review the code, and I believe it's happening because HOSTNAME is a bash environment variable and also in context.sh that is sourced in. When I applied the attached patch to unset HOSTNAME prior to sourcing context.sh, the correct hostname stays persistent across reboots. I'm not sure though if this is a "proper" fix for the issue, but it's working for us.

Example:
root@cjm1604:~# cat /run/cloud-init/instance-data.json | jq .v1
{
  "availability-zone": null,
  "cloud-name": "opennebula",
  "instance-id": "iid-dsopennebula",
  "local-hostname": "cjm1604",
  "region": null
}
root@cjm1604:~# reboot

root@ip-10-236-120-173:~# cat /run/cloud-init/instance-data.json | jq .v1
{
  "availability-zone": null,
  "cloud-name": "opennebula",
  "instance-id": "iid-dsopennebula",
  "local-hostname": "ip-10-236-120-173",
  "region": null
}
root@ip-10-236-120-173:~# reboot

root@cjm1604:~# cat /run/cloud-init/instance-data.json | jq .v1
{
  "availability-zone": null,
  "cloud-name": "opennebula",
  "instance-id": "iid-dsopennebula",
  "local-hostname": "cjm1604",
  "region": null
}
root@cjm1604:~# reboot

Let me know if you require any additional information.

Cheers,
Corey Melanson

[Scott Moser (smoser)]

Hi Corey,
It looks like you have correctly identified this bug and the right fix. bash was setting the HOSTNAME variable which was throwing a wrench into assumptions of the parse_shell_config.

Could you follow http://cloudinit.readthedocs.io/en/latest/topics/hacking.html and submit a merge proposal?

Please let me know if you have any questions. Feel free to ping in FreeNode IRC (smoser) or here.

[James Falcon (falcojr)]

Tracked in Github Issues as https://github.com/canonical/cloud-init/issues/3177