templates: explicitly set resource namespaces

[pgier]

We have a use case where we are generating manifests using helm template and then using kubectl apply to add them to the cluster. We can't use kubectl apply --namespace foo because helm template is generating resources for multiple namespaces, so the namespaces need to be set explicitly in the charts. This seems to be a common practice among other popular Helm charts (cert-manager, kube-prometheus-stack, etc).

[chrislin22]

Agreed. It seems that has been already used here:
https://github.com/chartmuseum/charts/blob/main/src/chartmuseum/templates/servicemonitor.yaml#L6