Concurrent modification error when creating a Service

[rhuss]

What version of Knative?

0.12.0

Expected Behavior

We would expect that the creation of a Service works without error

Actual Behavior

Sometimes (not always), when creating a very simple service like with kn service create hello --image gcr.io/knative-samples/helloworld-go we end up with the following events for the created Knative Service:

Events:
  Type     Reason         Age                From                Message
  ----     ------         ----               ----                -------
  Normal   Created        10m                service-controller  Created Configuration "hello"
  Normal   Created        10m                service-controller  Created Route "hello"
  Normal   Updated        10m (x3 over 10m)  service-controller  Updated Service "hello"
  Warning  InternalError  10m                service-controller  failed to reconcile Configuration: Operation cannot be fulfilled on configurations.serving.knative.dev "hello": the object has been modified; please apply your changes to the latest version and try again 

This ends up in the following service conditions:

 status:
  conditions:
  - lastTransitionTime: "2020-02-12T11:17:47Z"
    status: Unknown
    type: ConfigurationsReady
  - lastTransitionTime: "2020-02-12T11:17:48Z"
    message: Revision "hello-hnzcf-1" referenced in traffic not found.
    reason: RevisionMissing
    status: "False"
    type: Ready
  - lastTransitionTime: "2020-02-12T11:17:48Z"
    message: Revision "hello-hnzcf-1" referenced in traffic not found.
    reason: RevisionMissing
    status: "False"
    type: RoutesReady 

It looks like that an (internal) update of the Configuration clashes with the Configuration's reconciliation. I don't know though, why the Configuration (or service) needs to be updated.

We are using BYO revision name, so that might be the cause of this extra Service / Configuration update causing the collision.

See this client E2E log for a more complete dump of the situation.

Steps to Reproduce the Problem

It's flaky, but just try kn service create hello --image gcr.io/knative-samples/helloworld-go and in some case you get that behaviour (kn uses BYO revision names by default)

[navidshaikh]

Seeing following event as well with same error Message: Revision "hello-nxvfy-1" referenced in traffic not found.

Events:
  Type     Reason         Age              From                Message
  ----     ------         ----             ----                -------
  Warning  InternalError  5s (x8 over 5s)  service-controller  service: "hello" does not own configuration: "hello

client E2E logs

[markusthoemmes]

This has been forwarded since 0.14. @rhuss @navidshaikh are you still seeing this?

[navidshaikh]

@markusthoemmes : nope, didnt see this lately.

[rhuss]

Me neither. I think we are good to close this and create a new issue in case this should come back.