A/B testing support for Gloo Edge ingress controller

[kdorosh]

Resolves #707 , which is related to solo-io/gloo#3726

The approach here is to replace Gloo UpstreamGroups in the flagger implementation with Gloo RouteTables, which additionally support header/method matching used in A/B testing. For this to work, we needed to add and leverage the new inheritablePathMatcher field on Gloo RouteTables, thus these changes will only work in Gloo Edge 1.6.0-beta22 and higher. (Gloo Edge 1.6.0 release is slated for end of year)

Unit and integration tests all pass locally. Still running through the documented Gloo guide to ensure it's up to date, otherwise this PR is ready to be looked over. Going to mark as draft until I have finished reviewing the guide.

Appreciate the attention to developer experience and developer guide, thanks!

[kdorosh]

How does flagger versioning work? According to semver this is a new feature, so I put 1.5.0 here; please let me know what to put if that's not accurate.

[kdorosh]

note, the guide will not work as written until 1.6.0 is released in two weeks, as helm install installs the latest 1.5 release by default.

I can provide the --version flag to the helm install command if we want to hard-code the guide to a 1.6 version (for now, a beta). Thoughts?

[stefanprodan]

@kdorosh this looks great thanks! I think we should hold this off until there is a stable release of Goo with this feature.

How are Goo users suppose to upgrade, does it imply downtime? It would be nice for Gloo users to have a section in docs on how to upgrade from Flagger v.1.4 and Gloo 1.5 to Flagger v.1.5 and Gloo Edge 1.6.

[stefanprodan]

@kdorosh please open a PR agains main branch, I've delete master.

[kdorosh]

replaced by #765

w.r.t. #758 (review):

I think we should hold this off until there is a stable release of Goo with this feature.

1.6.0-beta22 is a release of Gloo that is live, and demonstrates the functionality that will be in the long-term-support version of 1.6 Gloo. I'm happy to come back and update to version tested against in two weeks, but would really like to avoid rebasing my PR on top of changes to this repo again (so far, twice: once for circle ci -> GH actions, and once for master -> main branch).

How are Goo users suppose to upgrade, does it imply downtime? It would be nice for Gloo users to have a section in docs on how to upgrade from Flagger v.1.4 and Gloo 1.5 to Flagger v.1.5 and Gloo Edge 1.6.

What do you imply by downtime? Time where you cannot run a canary release?

If so, the only downtime is for the 1.4.2 -> 1.5 flagger upgrade. Gloo 1.6 works with both upstream groups and route tables, so both old and new flagger versions will work.

The only change required of the user to use 1.5+ versions of flagger is to point their virtual service(s) toward a route table (to be generated by flagger) rather than an upstream group. The new guide demonstrates this when creating the new virtual service upfront. Happy to add a note to the new PR to clarify this (what would you want it to say?).

[stefanprodan]

Gloo 1.6 works with both upstream groups and route tables, so both old and new flagger versions will work.

All good then, thanks!