Unit testing for helm charts

[caugustus-sourcegraph]

Evaluate what options are available for unit testing helm charts and the effort involved in adoption / maintenance.

The main goal is to make it safe to refactor and add features to the chart. It is not intended for customers (if it's useful to them that's ok, it's just not a requirement here).

[github-actions[bot]]

Heads up @davejrt @ggilmore @dan-mckean @caugustus-sourcegraph - the "team/delivery" label was applied to this issue.

[kevinwojo]

Starting some research here:

• https://helm.sh/docs/topics/chart_tests/

• https://github.com/hashicorp/vault-helm/tree/main/test

  From what I gleaned from the Hashicorp setup, https://github.com/redhat-certification/chart-verifier will be helpful.

[caugustus-sourcegraph]

Some notes I gathered when thinking about this orignally. None of these tools are obviously a good fit for what we're hoping to accomplish but maybe there's something useful here.

For unit testing specifically:

• Helm-unittest (https://github.com/helm-unittest/helm-unittest, https://github.com/anikin-aa/helm-unittest)
• Terratest: https://blog.gruntwork.io/automated-testing-for-kubernetes-and-helm-charts-using-terratest-a4ddc4e67344

Other testing options:

• Conftest (https://github.com/open-policy-agent/conftest)
• Helm schema validation (https://helm.sh/docs/topics/charts/#schema-files)
• Kubetest (https://faun.pub/helm-charts-testing-2091a63a83af)

[kevinwojo]

PR: https://github.com/sourcegraph/deploy-sourcegraph-helm/pull/23