feat: Enable Gardener ingress annotations for dns (#250)

[JensAc]

This PR enables the use of Gardener ingress for automatic creation of Dnsentries, when the operator is run on a Gardener-based Kubernetes cluster.

[pmig]

Thanks for your contribution :-)

We are happy to support gardener.

Please make sure to not break clusters without this specific config map. A quick test would be to delete the glasskube-settings and shoot-info config map and restart the operator.

As an additional tip you can forward the MinIO service via:

kubectl port-forward -n glasskube-system svc/glasskube-minio 9000

and configure it in your local IDE with an additional env var:

MINIO_HOST_NAME:localhost

So you can connect your operator to a remote cluster.

[pmig]

The use of !! is generally not recommended it hides NullPointerExceptions. Especially in this case where an Exception is thrown if no config map with the name shoot-info can be found.

2023-08-10T17:32:09.837+02:00 [ReconcilerExecutor-configgenerator-182] ERROR i.j.o.p.e.ReconciliationDispatcher - Error during event processing ExecutionScope{ resource id: ResourceID{name='glasskube-settings', namespace='glasskube-system'}, version: 168764586} failed. 
java.lang.NullPointerException: Cannot invoke "io.fabric8.kubernetes.api.model.ConfigMap.getData()" because the return value of "io.fabric8.kubernetes.client.dsl.Resource.get()" is null
	at eu.glasskube.operator.config.ConfigService.getDynamicCloudProvider(ConfigService.kt:61)

This will break config map creation for non gardener managed clusters. I recommend a solution similar to .. ?.let { it.contains(...) }.

[JensAc]

Alright, I see. I misunderstood the behavior of .!!. So what about?

kubernetesClient.configMaps().inNamespace("kube-system")?.withName("shoot-info")?.get()?.data?.get("extensions")?.contains("shoot-dns-service") == true ->
                CloudProvider.gardener

I tried this at least, and it seams to be working fine, even the safe call chain does not look very pretty.
Sorry, I am new to Kotlin and tried to search the web for the reason why you've suggested a solution based on let but did not find any appropriate explanation. Maybe, you could point me somewhere?

[kosmoz]

Alright, I see. I misunderstood the behavior of .!!. So what about?

kubernetesClient.configMaps().inNamespace("kube-system")?.withName("shoot-info")?.get()?.data?.get("extensions")?.contains("shoot-dns-service") == true ->
                CloudProvider.gardener

I tried this at least, and it seams to be working fine, even the safe call chain does not look very pretty. Sorry, I am new to Kotlin and tried to search the web for the reason why you've suggested a solution based on let but did not find any appropriate explanation. Maybe, you could point me somewhere?

Yes that should work fine, although I think the first result that can actually be null is that of get(), so you can omit the first two safe calls. Using let (or another scope function) is not necessary here.

(Also, small correction: The !! operator does not hide NullPointerExceptions, it raises one if the value is null.)

[pmig]

We are happy to merge your contribution, with a small improvement - as kosmoz mentioned.

One last thing: Please squash your commits to a single commit following the conventional commit syntax.

[pmig]

Suggested change

	kubernetesClient.configMaps().inNamespace("kube-system")?.withName("shoot-info")?.get()?.data?.get("extensions")?.contains("shoot-dns-service") == true ->
	kubernetesClient.configMaps().inNamespace("kube-system").withName("shoot-info").get()?.data?.get("extensions")?.contains("shoot-dns-service") == true ->

as @kosmoz mentioned in his comment:

I think the first result that can actually be null is that of get(), so you can omit the first two safe calls

[JensAc]

We are happy to merge your contribution, with a small improvement - as kosmoz mentioned.

One last thing: Please squash your commits to a single commit following the conventional commit syntax.

I just did that. I am not entirely sure whether this is a good workflow, as I needed a force push in order to rewrite my history to a single commit. Wouldn't it make more sense that you simply "squash and merge"? Anyways, I hope I met your requirements now.