GEP: Default Gateways

[kflynn]

Original Title: Ana wants a concept of a default Gateway

Gateway API currently requires every north/south Route object to explicitly specify its parent Gateway. This is helpful in that it removes ambiguity, but it's less helpful in that Ana is stuck constantly explicitly configuring a thing that she probably doesn't care much about: in a great many cases, Ana's just wants to create a Route that works "from the outside world" and she really doesn't care what the Gateway is called. It also complicates Ana's life if she wants to, someday, install a Helm chart that includes a Route.

Therefore, Ana would like a way to be able to rely on a default Gateway that she doesn't have to name, and can simply trust to exist.

[howardjohn]

I'm not at all opposed to a native solution here but the new MutatingAdmission work could also be an option. We can provide one. Then it uses cel to fill in the parent if none set.

[youngnick]

I agree that making this easier for Ana is really important, but I also think it's really important to ensure that we don't lose the property that the parentRefs are explicitly specified.

The MutatingAdmission work would be great for that, and I think a default value for unsupplied parentRefs is also fine in the meantime.

[shaneutt]

This feature has been accepted for the v1.4.0 release. Please see this announcement for more details, and for the timing expectations for transitions. Note that if the timeline can not be met, there is a risk that this feature may unfortunately need to be dropped from the release. If you have any questions, concerns, or are in need of support please reach out to the maintainers so we can assist you!

Note: @mlavacca and @shaneutt are the assigned reviewers.

[Miciah]

Does "the new MutatingAdmission work" refer to the MutatingAdmissionPolicy API? Does this GEP boil down to a documentation update with an example yaml manifest for a MutatingAdmissionPolicy? Using a relatively straightforward MAP configuration object would be a good alternative to growing the Gateway API spec.