Deprecation of Direct Engine

https://blueprints.launchpad.net/sahara/+spec/deprecate-direct-engine

Currently Sahara has two types of infrastructure engines. First is Direct Infrastructure Engine and second is Heat Infrastructure Engine. This spec proposes deprecating the Direct Engine.

Problem description

Each time when Sahara start support new feature, Sahara should support it in both engines. So, it became much harder to support both versions of engines, because in case of Direct Engine it would need to have duplication of work, which is already done in Heat.

Proposed change

It’s proposed to deprecate Direct Engine in Liberty release, but it will be available to use. After merging this spec Direct Engine should be freezed for new feautures which will be added in Liberty. It will be opened for fixes of High and Critical bugs. We should make Heat Engine used by default in Sahara.

This change will allow to switch most testing jobs in Sahara CI to use Heat Engine instead of Direct Engine.

In M release we should remove all operations from direct engine. After that the only operation which can be done with direct-engine-created cluster is the cluster deletion. We should rewrite cluster deletion behavior to support deletion direct-engine-created cluster via Heat Engine. Now heat engine removes cluster from database but doesn’t remove all cluster elements (for example, instances).

Alternatives

Sahara can continue support of both engines.

Data model impact

None

REST API impact

None

Other end user impact

None

Deployer impact

Deployers should switch to use Heat Engine instead of Direct Engine.

Developer impact

New features, which impacts infrastructure part of Sahara, should be supported only in Heat Engine.

Sahara-image-elements impact

None

Sahara-dashboard / Horizon impact

None

Implementation

Assignee(s)

Primary assignee:
vgridnev
Other contributors:
None

Work Items

This change will require following changes:

  • Add deprecation warnings at sahara startup.
  • Mark Heat Engine as default in Sahara.
  • Document deprecation of Direct Engine.

Dependencies

None

Testing

This change require manual testing of deletion direct-engine-created cluster after switch to heat engine.

Documentation Impact

Need to document that Direct Engine became deprecated.

References

None