Stale listener condition present in Gateway for a non-existing Listener

[chauhanshubham]

Description:
Following the reproduction steps, it is seen that the Gateway is left with a stale listener condition, for a listener
that no longer exists.

Repro steps:

1. apply examples/kubernetes/quickstart.yaml - ensure that Gateway has proper Status conditions, with 1 listener condition
   showing attachedRoutes: 1.
2. Add another listener in the gateway, for the listener spec to look something like this

listeners:
- allowedRoutes:
     namespaces:
       from: Same
     name: http
     port: 8080
     protocol: HTTP
- allowedRoutes:
     namespaces:
       from: Same
     name: http2
     port: 8081
     protocol: HTTP 

This should create 2 listener conditions, both specifying attachedRoutes: 1.
3. Remove the single HTTPRoute that was created by the quickstart.yaml. Both existing listener conditions are updated correctly, specifying attachedRoutes: 0.
4. Re-apply the quickstart.yaml which will "recreate" the HTTPRoute, and "update" the Gateway to have only one listener.
5. The bug is that - in the Gateway status still shows the stale listener Condition corresponding to listener http2 with attachedRoutes: 0
The spec and status thus looks like this

 spec:
    gatewayClassName: eg
    listeners:
    - allowedRoutes:
        namespaces:
          from: Same
      name: http
      port: 8080
      protocol: HTTP
  status:
    ....
    conditions:
    ....
    listeners:
    - attachedRoutes: 1
      conditions:
      - lastTransitionTime: "2022-12-03T06:58:58Z"
        message: Listener is ready
        observedGeneration: 3
        reason: Ready
        status: "True"
        type: Ready
      name: http
      supportedKinds:
      - group: gateway.networking.k8s.io
        kind: HTTPRoute
    - attachedRoutes: 0
      conditions:
      - lastTransitionTime: "2022-12-03T06:58:48Z"
        message: Listener is ready
        observedGeneration: 2
        reason: Ready
        status: "True"
        type: Ready
      name: http2
      supportedKinds:
      - group: gateway.networking.k8s.io
        kind: HTTPRoute

[arkodg]

thanks for raising this issue, there are two ways to fix this issue

• either we always reset the listener status before computing it in

  gateway/internal/gatewayapi/translator.go

  Line 189 in 7b73d14

  func (t *Translator) ProcessListeners(gateways []*GatewayContext, xdsIR XdsIRMap, infraIR InfraIRMap, resources *Resources) {

• or once we are done computing newer listener status, we parse through all listener status and remove the stale ones

[haq204]

Hi @arkodg I can take on this issue since I have another issue currently blocked by the 0.6.0 gateway-api bump.

From a brief scan, it seems like the easiest way is to reset the listener status before computing. It doesn't look like ProcessListeners is responsible for communicating to the API server for updating the status which was my initial concern but I think it seems safe to do because the gatewayapi translator will always update the status for all gateways for a given ingress class before sending a message back to the K8s provider to update the status to the K8s API server though I could be wrong on that last part.

[arkodg]

yeah @haq204 the easiest/cleanest approach is the one you suggested, to just reset the status conditions before starting translation in the Gateway API library. It would look similar to

gateway/internal/gatewayapi/translator.go

Line 134 in 97032be

// Reset conditions and attached route count

[arkodg]

we also need to ensure that resetting and recomputing the status doesnt end up updating the status condition in K8s if the condition is same (all fields except LastTransitionTime is same)
this is taken care of today here

gateway/internal/status/status.go

Line 163 in 97032be

func isStatusEqual(objA, objB interface{}) bool {

but we need to verify that is working as intended

[danehans]

@haq204 thanks for taking on this issue. Is the issue still TODO or have you made any progress with it?

[haq204]

@danehans still TODO but will try to tackle it this week