Hypervisors in nova - no subpage details for ironic

[Matt Riedemann]

- [x] This is a doc addition request.

The admin configuration for hypervisors does not have a subpage with details about configuring nova with the ironic compute driver. There are at least a few things that could go into a page like that:

* Summary of what it does and how it interacts with the ironic service as a 'hypervisor'. Some of that information is available in the ironic docs, e.g.:

https://docs.openstack.org/ironic/latest/install/get_started.html?highlight=nova#interaction-with-openstack-components

Since it comes up from time to time, I would also mention that the ironic driver is the only one in nova where the compute_nodes table record is 1:M with the compute services table record for the given host, meaning a nova-compute service can manage multiple ComputeNodes, and the ComputeNodes for the ironic driver managed compute service uses the ironic node uuid for the compute node hypervisor_hostname (nodename) and uuid fields. And ironic node : compute node : instance are 1:1:1. This is more contributor/reference information but it's worth mentioning somewhere since it's kind of tribal knowledge in nova.

* Ironic-specific configuration: https://docs.openstack.org/nova/latest/configuration/config.html#ironic

- This could also include things like configuring baremetal flavors: https://docs.openstack.org/ironic/latest/install/configure-nova-flavors.html

- Running multiple nova-computes in HA mode managing the same set of nodes:

https://specs.openstack.org/openstack/nova-specs/specs/newton/implemented/ironic-multiple-compute-hosts.html

* Scaling and performance issues. Some of this is discussed in this mailing list thread:

http://lists.openstack.org/pipermail/openstack-discuss/2019-November/thread.html#10655

- Partitioning schemes: https://specs.openstack.org/openstack/nova-specs/specs/stein/implemented/ironic-conductor-groups.html

* Known limitations / missing features, e.g. move operations (migrate/resize).

-----------------------------------
Release: on 2018-09-04 18:11:45
SHA: 8a71962e0149fa9ad7f66c17849bf69df3e78d33
Source: https://opendev.org/openstack/nova/src/doc/source/admin/configuration/hypervisors.rst
URL: https://docs.openstack.org/nova/latest/admin/configuration/hypervisors.html

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/701998

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/701998
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=1efd5ec2328b82092d8cc46574b29fa315b9acfd
Submitter: Zuul
Branch: master

commit 1efd5ec2328b82092d8cc46574b29fa315b9acfd
Author: Iury Gregory Melo Ferreira <email address hidden>
Date: Thu Jan 9 14:41:10 2020 +0100

    Add ironic hypervisor doc

    Nova documentation was missing information documentation about
    Ironic virt driver.

    Change-Id: I2431dc3db94da44001eefdead50607eab662d16f
    Closes-Bug: #1852446