Helm export YAML files locally (just use templating engine, do not send to Kubernetes)

We need logs to check the Unauthorized issue.

But you can easily generate templates locally:

helm template mychart

Render chart templates locally and display the output.

This does not require Tiller. However, any values that would normally be looked up or retrieved in-cluster will be faked locally. Additionally, none of the server-side testing of chart validity (e.g. whether an API is supported) is done.

More info: https://docs.helm.sh/helm/#helm-template

Amrit Bera's solution will only work with local helm chart, per the details of your question you want it to work with remote helm chart, that's a feature that will be added to Helm v3 (Work in Progress currently).

RehanSaeed posted the following workaround (https://github.com/helm/helm/issues/4527)

Basically:

mkdir yamls
helm fetch --untar --untardir . 'stable/redis' #makes a directory called redis 
helm template --output-dir './yamls' './redis' #redis dir (local helm chart), export to yamls dir

The good thing about this is you can mix this technique with weaveworks flux for git ops + this gives you another option for using Helm v2 without tiller, in addition to the Tiller Plugin (which lets you run tiller locally, but doesn't work smoothly).

Straight from the helm install --help

To check the generated manifests of a release without installing the chart,
the '--debug' and '--dry-run' flags can be combined. This will still require a
round-trip to the Tiller server.