[Openstack-operators] [nova] [neutron] Should we continue providing FQDNs for instance hostnames?

Stephen Finucane sfinucan at redhat.com
Fri Sep 8 09:12:17 UTC 2017

[Re-posting (in edited from) from openstack-dev]

Nova has a feature whereby it will provide instance host names that cloud-init
can extract and use inside the guest, i.e. this won't happen without cloud-
init. These host names are fully qualified domain names (FQDNs) based upon the
instance name and local domain name. However, as noted in bug #1698010 [1], the
domain name part of this is based up nova's 'dhcp_domain' option, which is a
nova-network option that has been deprecated [2].

My idea to fix this bug was to start consuming this information from neutron
instead, via the . However, per the feedback in the (WIP) fix [3], this
requires requires that the 'DNS Integration' extension works and will introduce
a regression for users currently relying on the 'dhcp_domain' option. This
suggests it might not be the best approach to take but, alas, I don't have any
cleverer ones yet.

My initial question to openstack-dev was "are FQDNs a valid thing to use as a
hostname in a guest" and it seems they definitely are, even if they're not
consistently used [4][5]. However, based on other comments [6], it seems there
are alternative approaches and even openstack-infra don't use this
functionality (preferring instead to configure hostnames using their
orchestration software, if that's what nodepool could be seen as?). As a
result, I have a new question: "should nova be in the business of providing
this information (via cloud-init and the metadata service) at all"?

I don't actually have any clever ideas regarding how we can solve this. As
such, I'm open to any and all input.


[1] https://bugs.launchpad.net/nova/+bug/1698010
[2] https://review.openstack.org/#/c/395683/
[3] https://review.openstack.org/#/c/480616/
[4] http://lists.openstack.org/pipermail/openstack-dev/2017-September/121948.ht
[5] http://lists.openstack.org/pipermail/openstack-dev/2017-September/121794.ht
[6] http://lists.openstack.org/pipermail/openstack-dev/2017-September/121877.ht

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