Is template function .Capabilities.APIVersions.has reliable using helm template?

[ebuildy]

Output of helm version: v3.8.1

Output of kubectl version: v1.19.15

Cloud Provider/Platform (AKS, GKE, Minikube etc.): on premise (kubespray)

Deploy workflow: using argoCD (helm template)

Helm template snippet:

{{- if .Capabilities.APIVersions.Has "policy/v1" -}}
apiVersion: policy/v1
{{- else}}
apiVersion: policy/v1beta1
{{- end }}

Trouble

helm template --kube-version 1.19.0 --api-versions policy/v1beta1 . should display apiVersion: policy/v1beta1 but .Capabilities.APIVersions.Has "policy/v1" returns true. In my understanding, --kube-version 1.19.0 should make Helm , k8s 1.19.0 compatible.

helm install is OK, but argoCD is doing a helm template.

(I took the snippet from https://github.com/elastic/helm-charts/blob/main/elasticsearch/templates/poddisruptionbudget.yaml )

I see bitnami is doing this instead of relying on .Capabilities.APIVersions.Has function: https://github.com/bitnami/charts/blob/master/bitnami/common/templates/_capabilities.tpl#L65

{{/*
Return the appropriate apiVersion for poddisruptionbudget.
*/}}
{{- define "common.capabilities.policy.apiVersion" -}}
{{- if semverCompare "<1.21-0" (include "common.capabilities.kubeVersion" .) -}}
{{- print "policy/v1beta1" -}}
{{- else -}}
{{- print "policy/v1" -}}
{{- end -}}
{{- end -}}

Is template function .Capabilities.APIVersions.has reliable? or is it a bug on argoCD side?

Or should I use only Helm v3.5.X with kubernetes v1.19? (according https://github.com/helm/helm/blob/v3.5.4/go.mod#L47)

[bacongobbler]

helm template does not reach out to a Kubernetes cluster. It uses whatever APIVersions the Kubernetes client provides unless you pass the --validate flag.

[ebuildy]

By Kubernetes client , you mean the one compiled?

[bacongobbler]

Yes.

[ebuildy]

ok I see, to sum up: helm template function .Capabilities.APIVersions.has is not reliable when using argoCD .

Related to argoproj/argo-cd#3640

Thanks you, I am continuing on this side.

[Morriz]

Hi, is there any documentation on how to make helm template --kube-version='1.22' --api-versions='networking.k8s.io/v1/Ingress ...' actually use those api-versions without needing any cluster context?