Incorrect usage of --api-versions helm flag in README about kubepug HOT 4 OPEN

@rikatz here is a link to the helm template documentation where you can see:

-a, --api-versions stringArray Kubernetes api versions used for Capabilities.APIVersions

However, it looks like there is now a --kube-version arg that was just released in helm 3.6.0 today where you can specify the kube version to use. With that in mind, it looks like this should just be a quick docs fix. @mteodori

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Hi @mteodori thanks for raising this.

Can you provide me some more specific steps to reproduce, so I can take a look here? I'm shamefully not much aware of helm behavior :)

Thank you!

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Or I can take a look into the original issue in helm :)

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Unfortunately, the helm --kube-version argument does not work like kubepug --k8s-version.

KubePug uses --k8s-version to determine the swagger.json for the requested Kubernetes version and from there extracts all the supported API Versions.

Helm on the other hand simply uses --kube-version as the value for .Capabilities.KubeVersion. It does not determine all the supported API Versions for that Kubernetes Version and populate .Capabilities.ApiVersions. Helm uses the API Versions for the compiled-in kubectl version

Unfortunately, this means that (using Helm 3.10.2) this command will template a chart with API Versions for kubernetes 1.25.2 (because of the compiled in version of kubectl) while KubePug will be validating for API Versions for kubernetes 1.22.0
helm template . | kubepug --k8s-version v1.22.0 --input-file=-

If we use helm template . --kube-version 1.22.0 | kubepug --k8s-version v1.22.0 --input-file=- this only changes .Capabilities.KubeVersion in the Helm templating - it does not affect the values of .Capabilities.APIVersions.

In order to have helm use the API Versions for the desired kubernetes version, we must use helm template argument --api-versions. For the current kubernetes cluster, that looks like
helm template $(kubectl api-versions | awk '{printf "--api-versions %s ",$0}') . | kubepug --k8s-version v1.22.0 --input-file=-

However, there is no mechanism to get the api-versions for a non-running cluster. We want to test our charts against the current cluster version and the next 2 minor versions, e.g. 1.22.0, 1.23.0, 1.24.0. But this is simply not possible with Helm unless you have a cluster of each version running.

It would be a great kubepug feature to output the api-versions for a given Kubernetes version so that we could feed that into helm template because kubepug has already parsed this information from the swagger.json.

For example, it would be great if we could do this:

for K8S_VERSION in v1.22.0 v1.23.0 v1.24.0; do
  helm template --kube-version=$K8S_VERSION \
    $(kubepug api-versions --k8s-version $K8S_VERSION | awk '{printf "--api-versions %s ",$0}') . |
    kubepug --k8s-version $K8S_VERSION --input-file=-
done

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