Set readiness probe port based on user's configuration

[ZhiminXiang]

/area networking
/kind dev

Expected Behavior

We should set readiness probe's port based on user's configuration.

Actual Behavior

Currently we always use RequestQueuePort as readiness probe port.

serving/pkg/controller/revision/pod.go

Line 115 in 71511cf

userContainer.ReadinessProbe.Handler.HTTPGet.Port = intstr.FromInt(queue.RequestQueuePort)

[ZhiminXiang]

@mdemirhan @tcnghia

[tcnghia]

The spec also mentions the kind of Readiness check if user don't provide HTTP health check (we'll resort to a TCP handshake).

[tcnghia]

According to spec, the user container always listen on :8080 right? This is hard-wired to queue-controller, and that in turn is exposed at RequestQueuePort.

By doing health check through RequestQueuePort we can make sure the health check is more end-to-end.

[tcnghia]

So I think there is no issue here, please reopen if there are other things that we need to address.

[ZhiminXiang]

I see. yea we should always send request to RequestQueuePort.

But when user defines their own port (e.g. 8042) for health check, should we redirect the health check request to 8042 in the queue proxy? Currently we always direct the request to 8080 in queue proxy.

@tcnghia

[tcnghia]

I see, I think we can change to only use RequestQueuePort if the port is missing or same as the main port. Otherwise we leave it the same. Adding more proxies may over-complicate things with not a lot to gain.

[mattmoor]

/assign @dgerd