Create GenericKubernetesResource from file without ResourceDefinitionContext

[SoerenHenning]

Hi, I'm looking for a simple way to resemble something like kubectl apply -f resource-of-any-kind.yaml in Java. resource-of-any-kind.yaml might be a custom resource, which is not under my control so the Typeless API should be the way to go. However, to use that API I need to create a ResourceDefinitionContext object, which I do not really can since I don't know the resource type of resource-of-any-kind.yaml (only by looking into the file).

Is there any way to let fabric8 Kubernetes client create that context under the hood? If not, how can this be done programmatically? How does kubectl manage this?

[shawkins]

This is supported by 5.11+. See the issues referenced with #3547.

[manusa]

Just to provide an example:

kubernetesClient.resource("you-resource-as-yaml").createOrReplace();
kubernetesClient.load(yourResourceAsInputStream).createOrReplace();

The client will infer your context by querying the cluster for the APIs responsible of the provided resource Kind+apiVersion.

---

Edit (2022-03-12):

As suggested by @shawkins later in this discussion, in case you are testing this implementation with our KubernetesMockServer, then you'd need to setup some expectations for your API (if your YAML contains an entry for a non-core resource):

    ResourceDefinitionContext rdc = new ResourceDefinitionContext.Builder()
        .withGroup("test.fabric8.io")
        .withVersion("v1alpha1")
        .withKind("hello")
        .withNamespaced(true)
        .withPlural("hellos")
        .build();

    server.expect()
        .get()
        .withPath(String.format("/apis/%s/%s", rdc.getGroup(), rdc.getVersion()))
        .andReturn(HttpURLConnection.HTTP_OK,
            new APIResourceListBuilder()
                .withResources(
                    new APIResourceBuilder().withKind(rdc.getKind())
                        .withNamespaced(rdc.isNamespaceScoped())
                        .withName(rdc.getPlural())
                        .build())
                .build())
        .once();

[manusa]

A workaround for CRUD mode would be to add the specific expectations for the API resource metadata endpoints, but I haven't tested it.

Same expectations + others could be used for the non-CRUD mode.

[shawkins]

Yes that should work, no need to customize the server. I was getting mixed up with how built-in handling was added for root paths. You can use (and we can add a utility method to the KubernetesServer under #3960) in crud or non-crud:

    ResourceDefinitionContext rdc = new ResourceDefinitionContext.Builder()
        .withGroup("test.fabric8.io")
        .withVersion("v1alpha1")
        .withKind("hello")
        .withNamespaced(true)
        .withPlural("hellos")
        .build();

    server.expect()
        .get()
        .withPath(String.format("/apis/%s/%s", rdc.getGroup(), rdc.getVersion()))
        .andReturn(HttpURLConnection.HTTP_OK,
            new APIResourceListBuilder()
                .withResources(
                    new APIResourceBuilder().withKind(rdc.getKind())
                        .withNamespaced(rdc.isNamespaceScoped())
                        .withName(rdc.getPlural())
                        .build())
                .build())
        .once();

For this to work at a high level in crud mode we'd need to be able to issue an APIResource POST, but we don't have any method for that currently.

[manusa]

For this to work at a high level in crud mode we'd need to be able to issue an APIResource POST, but we don't have any method for that currently.

Maybe special handling of APIService could take care of this, but it would really complicate things.

Adding an accessor to be able to be able to manually register ResourceDefinitionContext in the KubernetesAttributesExtractor would be the easiest approach.

[shawkins]

Moved further discussion over to #3960 (comment)

[SoerenHenning]

Thank you for the huge support! I was able to get my tests run with the code snipped provided by @shawkins. With the help of Kotlin extension functions, this currently everything I need.

[manusa]

I'm going to edit my answer to include Steven's snippet so you can get a complete answer without going through the discussion.

[chenzhihao]

Thanks! This answer is pretty helpful. Could we add this to the document?