Hostname changes after every reboot with OpenNebula

This bug was originally filed in Launchpad as [LP: #1771145](https://bugs.launchpad.net/cloud-init/+bug/1771145)

Launchpad details

affected_projects = []

assignee = None

assignee_name = None

date_closed = None

date_created = 2018-05-14T16:07:05.383801+00:00

date_fix_committed = None

date_fix_released = None

id = 1771145

importance = medium

is_complete = False

lp_url = https://bugs.launchpad.net/cloud-init/+bug/1771145

milestone = None

owner = cmelanson

owner_name = Corey Melanson

private = False

status = triaged

submitter = cmelanson

submitter_name = Corey Melanson

tags = []

duplicates = []

_Launchpad user **Corey Melanson(cmelanson)** wrote on 2018-05-14T16:07:05.383801+00:00_

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