Pausing a HA-enabled charm won't migrate resources, only pausing the hacluster subordinate will

[Andrea Ieri]

This bug tracker is for errors with the documentation, use the following as a template and remove or add fields as you see fit. Convert [ ] into [x] to check boxes:

- [x] This doc is inaccurate in this way: pausing nova-cloud-controller or neutron-api won't move the VIP, as it might be assumed
- [ ] This is a doc addition request.
- [ ] I have a fix to the document that I can paste below including example: input and output.

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-----------------------------------
Release: 0.1 on 2018-12-06 04:40
SHA: a247937c844c5ede804c7d04e2927670f38d09f5
Source: Can't derive source file URL
URL: https://docs.openstack.org/project-deploy-guide/charm-deployment-guide/latest/app-upgrade-openstack.html

The "HA with pause/resume" section (https://docs.openstack.org/project-deploy-guide/charm-deployment-guide/latest/app-upgrade-openstack.html#ha-with-pause-resume) may lead people to think that pausing nova-cloud-controller will also ensure that the VIP will be moved elsewhere if needed.
This is only true if the hacluster subordinate is paused as well.
I suggest to rewrite the CLI example as follows:

juju config nova-cloud-controller action-managed-upgrade=True
juju config nova-cloud-controller openstack-origin='cloud:xenial-pike'
juju run-action ncc-hacluster/2 --wait pause
juju run-action nova-cloud-controller/2 --wait pause
juju run-action nova-cloud-controller/2 --wait openstack-upgrade
juju run-action nova-cloud-controller/2 --wait resume
juju run-action ncc-hacluster/2 --wait resume
juju run-action ncc-hacluster/1 --wait pause
juju run-action nova-cloud-controller/1 --wait pause
juju run-action nova-cloud-controller/1 --wait openstack-upgrade
juju run-action nova-cloud-controller/1 --wait resume
juju run-action ncc-hacluster/1 --wait resume
juju run-action ncc-hacluster/0 --wait pause
juju run-action nova-cloud-controller/0 --wait pause
juju run-action nova-cloud-controller/0 --wait openstack-upgrade
juju run-action nova-cloud-controller/0 --wait resume
juju run-action ncc-hacluster/0 --wait resume

[Andrea Ieri (aieri)]

Note: pausing the principal charm would probably be enough if LP#1810919, LP#1810918, and LP#1810926 were fixed. Pausing hacluster will however always be a little cleaner as it puts the node on standby in the cib, whereas pausing the principal charm masks haproxy and must rely on pacemaker noticing and acting upon that.

[Peter Matulis (petermatulis)]

This has been fixed here:

https://review.opendev.org/690454