fix: standalone workflows now fail on top-level cycles

[yarinkos]

Workflow toplevel resoruces size

The next looks like a runtime deadlock issue , and I would like to suggest a fix
There is no point for a workflow builder with zero size toplevel resources ( A bit illogically ).

The following builder isn't common , but it demonstrates how wrong workflow configuration could lead for a deadlock state (topLevelResources.size() == 0, cycle detection still does not implemented )

  initDependentResources(kubernetesClient);
  workflow = new WorkflowBuilder<WebPage>()
        .addDependentResource(configMapDR)
        .addDependentResource(deploymentDR).dependsOn(configMapDR)
        .addDependentResource(serviceDR).dependsOn(deploymentDR)
        .addDependentResource(ingressDR).dependsOn(serviceDR)
            .addDependentResource(configMapDR).dependsOn(serviceDR)
            .build();

For cases where the initializations aren't logical, this exception throw can comes in
Hope is following the guidelines and the project roadmap.
r.m.k

[csviri]

Hi @yarinkos , thank you, this makes sense to some extent, just few points.

1. please run mvn clean install it will format the code, that is why the build is failing.
2. please add unit test for this

Note that this not necessarily detects cycles in all cases.

[csviri]

There is cycle detection for managed case: https://github.com/java-operator-sdk/java-operator-sdk/blob/077bbc2f224ee7fcc9da933aefd6c46aa51f95dd/operator-framework-core/src/main/java/io/javaoperatorsdk/operator/processing/dependent/workflow/ManagedWorkflowSupport.java#L59-L59

We could also properly do cycle detection to standalone mode. Still consider this as a good first step.

[metacosm]

A more explicit message would be better as this doesn't really help the user fix the problem.

[csviri]

Here just wanted to comment that :)
But basically as mentioned below, this just detects in some cases the cycles. But yes would check here if there is more than 0 resources, and if there is no top then it's a cycle.

[csviri]

Here just wanted to comment that :)
But basically as mentioned below, this just detects in some cases the cycles. But yes would check here if there is more than 0 resources, and if there is no top then it's a cycle.

[metacosm]

Thank you!