Add ability to control function instance pod min and max number at function schema about openfunction

[benjaminhuo]

Thanks @zhaibian, this is a very good proposal.
Currently we've pod template and keda scaled object defined and user can control min/max replica by setting these params.

But we might need a more direct way to specify the min/max replicas, @tpiperatgod @wanjunlei what do you think?

[zhaibian]

Got your idea. This is my thinking:

1. keda can be defined at scaled object spec
2. but knative need to define using annotations ways which openfunction serving has not supported

Even it works, different ways to define the same ability which is not graceful.
Uniform definition ways is better to mask the underlying complexity.

[benjaminhuo]

zhaibian

Got your idea. This is my thinking:

1. keda can be defined at scaled object spec
2. but knative need to define using annotations ways which openfunction serving has not supported

Even it works, different ways to define the same ability which is not graceful. Uniform definition ways is better to mask the underlying complexity.

Agree, a unified definition to min/max replicas is needed.
@wenchajun would you write a proposal for this and then create a PR?

[wenchajun]

Agree, a unified definition to min/max replicas is needed.
@wenchajun would you write a proposal for this and then create a PR?

Ok, I'll finish it.

[tpiperatgod]

I would prefer to add a new property to spec.serving in function cr to support this feature, as it is a feature of the serving phase.

At the same time, we may also need to consider the design of the annotation section to provide the ability to support new features in an annotated form in the future.

[wenchajun]

I have written a proposal, please see https://hackmd.io/A-r2frbVTpiDhpfNc7ac2w. We can discuss and complete it.