Is it possible to manage external helm repositories? Or is it expected that the chart be installed and updated outside the pulumi program? For instance, I have this shell script:

# Add the Jetstack Helm repository
helm repo add jetstack <https://charts.jetstack.io>

# Update your local Helm chart repository cache
helm repo update

# Install the cert-manager Helm chart
helm install \
  --name cert-manager \
  --namespace cert-manager \
  --version v0.11.0 \
  jetstack/cert-manager

You can manage the charts themselves using Pulumi, but the repo add/update is local to your machine for now. There are a number of examples on the pulumi/examples GitHub repo