Refactor top level puppet manifests

Launchpad blueprint:

https://blueprints.launchpad.net/tripleo/+spec/refactor-puppet-manifests

The current overcloud controller puppet manifests duplicate a large amount of code between the pacemaker (HA) and non-ha version. We can reduce the effort required to add new features by refactoring this code, and since there is already a puppet-tripleo module this is the logical destination.

Problem Description

Large amounts of puppet/manifests/overcloud_controller.pp are shared with puppet/manifests/overcloud_controller_pacemaker.pp. When adding a feature or fixing a mistake in the former, it is frequently also an issue in the latter. It is a violation of the common programming principle of DRY, which while not an inviolable rule, is usually considered good practice.

In addition, moving this code into separate classes in another module will make it simpler to enable/disable components, as it will be a matter of merely controlling which classes (profiles) are included.

Finally, it allows easier experimentation with modifying the ‘ha strategy’. Currently this is done using ‘step’, but could in theory be done using a service registry. By refactoring into ha+non-ha classes this would be quite simple to swap in/out.

Proposed Change

Overview

While there are significant differences in ha and non-ha deployments, in almost all cases the ha code will be a superset of the non-ha. A simple example of this is at the top of both files, where the load balancer is handled. The non ha version simply includes the loadbalancing class, while the HA version instantiates the exact same class but with some parameters changed. Across the board the same classes are included for the openstack services, but with manage service set to false in the HA case.

I propose first breaking up the non-ha version into profiles which can reside in puppet-tripleo/manifests/profile/nonha, then adding ha versions which use those classes under puppet-tripleo-manifests/profile/pacemaker. Pacemaker could be described as an ‘ha strategy’ which in theory should be replaceable. For this reason we use a pacemaker subfolder since one day perhaps we’ll have an alternative.

Alternatives

We could leave things as they are, which works and isn’t the end of the world, but it’s probably not optimal.

We could use kolla or something that removes the need for puppet entirely, but this discussion is outside the scope of this spec.

Security Impact

None

Other End User Impact

It will make downstreams happy since they can sub in/out classes more easily.

Performance Impact

Adding wrapper classes isn’t going to impact puppet compile times very much.

Other Deployer Impact

None

Developer Impact

Changes in t-h-t and puppet-tripleo will often be coupled, as t-h-t defines the data on which puppet-tripleo depends on.

Implementation

Assignee(s)

Primary assignee:
michaeltchapman

Work Items

Move overcloud controller to profile classes Move overcloud controller pacemaker to profile classes Move any other classes from the smaller manifests in t-h-t

Dependencies

None

Testing

No new features so current tests apply in their entirety. Additional testing can be added for each profile class

Documentation Impact

None

References

None