Goal: Support for multiple external gateways feature in OVN-Kubernetes

Why is this important: Customers and partners have shown interest in having official support for this feature.

Dependencies (internal and external):

Partner support for the ingress use case of this feature for a full solution. However, that does not gate our engineering from completing our implementation.

Prioritized epics + deliverables (in scope / not in scope):

Not in scope:

Estimate (XS, S, M, L, XL, XXL):

L

Previous Work:

Multiple external gateways functionality already exists in upstream ovn-org/ovn-kubernetes. It is configured via annotations today. To officially support it we need to turn the API into a CRD, and we also need a way for upgrading from the previous version to the new version.

Open questions:

How can we include testing for this feature in our downstream CI?

Acceptance criteria:

Epic Done Checklist:

• CI - CI Job & Automated tests: <link to CI Job & automated tests>
• Release Enablement: <link to Feature Enablement Presentation> 
• DEV - Upstream code and tests merged: <link to meaningful PR orf GitHub Issue>
• DEV - Upstream documentation merged: <link to meaningful PR or GitHub Issue>
• DEV - Downstream build attached to advisory: <link to errata>
• QE - Test plans in Polarion: <link or reference to Polarion>
• QE - Automated tests merged: <link or reference to automated tests>
• DOC - Downstream documentation merged: <link to meaningful PR>
• Notes for Done Checklist: 
  • Adding links to the above checklist with multiple teams contributing; select a meaningful reference for this Epic.
  • Checklist added to each Epic in the description, to be filled out as phases are completed - tracking progress towards “Done” for the Epic.