...

1. Install one node at a time, either by reinstalling it using the zedmodules/tags or by folloing this list::
   1. Run puppet with zed modules/tags

   2. Run systemctl stop puppet apache2

   3. Run apt-get purge placement-api placement-common python3-placement && apt-get autoremove && apt-get dist-upgrade
   4. Run puppet again

Nova

To upgrade nova without any downtime, follow this procedure

Preperations

Before the upgrades can be started it is important that all data from previous nova-releases are migrated to xena release. This is done like so:

• Run nova-manage db online_data_migrations on an API node. Ensure that it reports that nothing more needs to be done.

Nova API

1. In the node-specific hiera, disable the services at the first node you would like to upgrade with the keys

   1. apache::service_ensure: 'stopped'

2. Do one of:
   1. Run puppet with the zed modules/tags, Run apt dist-upgrade && apt-get autoremove
   2. Reinstall the node with zed modules/tags
3. Run nova-manage api_db sync
4. Run nova-manage db sync
5. Re-enable nova API on the upgraded node:
   
   1. Remove apache::service_ensure: 'stopped' from the upgraded node's hiera file
6. Upgrade the rest of the nodes (basically run step 2)

Nova-services

Either reinstall the node using the zed modules/tags, or follow this list:

1. Run puppet with the zed modules/tags
2. Run apt dist-upgrade && apt-get autoremove
3. Run puppet and restart services

Heat

The rolling upgrade procedure for heat includes a step where you are supposed to create a new rabbit vhost. I don't want that. Therefore, this is the cold upgrade steps.

...