bug: helm cli version 3.2.0 is failing in vault-helm-test during bats unit test

[anapsix]

Description of the bug
In CircleCI, vault-helm-test image used for test-unit (bats /helm-test/test/unit) is using bugged version of Helm CLI client (v3.2.0) failling to render a valid templates. The same templates are passing bats unit tests and are rendering just fine using Helm CLI version v3.6.0.
Based on my tests going through every version of Helm CLI from 3.2.0 and up, the rendering issue is fixed in v3.5.0

Test Image:

• docker.mirror.hashicorp.services/hashicorpdev/vault-helm-test:0.1.0
• docker.mirror.hashicorp.services/hashicorpdev/vault-helm-test@sha256:62b548d0b1bc07c2ec37133c60a441414c62fe3ee34692588f0c2c56be5d177e
  Link to the failing CI job: https://app.circleci.com/pipelines/github/hashicorp/vault-helm/810/workflows/9333e106-c18e-4331-848a-b20c576620c4/jobs/1061

To Reproduce
Steps to reproduce the behavior:

1. Clone my fork and switch to allow-templated-extracontainers branch (related to process extraInitContainers and extraContainers with tpl #536)

   git clone git@github.com:anapsix/vault-helm.git anapsix-vault-helm
   cd anapsix-vault-helm
   git checkout allow-templated-extracontainers

2. Pull the image CI is using for bats unit tests

   docker pull docker.mirror.hashicorp.services/hashicorpdev/vault-helm-test:0.1.0

3. Run bats unit test

   docker run \
     -it \
     --rm \
     -v "${PWD}:/src" \
     -w /src \
     docker.mirror.hashicorp.services/hashicorpdev/vault-helm-test:0.1.0 \
     bash -c 'helm version; bats /src/test/unit/server-statefulset.bats'

4. Observe the failure
5. Try again with new version of Helm

   docker run \
     -it \
     --rm \
     -v "${PWD}:/src" \
     -w /src \
     docker.mirror.hashicorp.services/hashicorpdev/vault-helm-test:0.1.0 \
     bash -c 'wget -O- https://get.helm.sh/helm-v3.6.0-linux-amd64.tar.gz | tar -xzC /usr/local/bin --strip-components 1 linux-amd64/helm; helm version; bats /src/test/unit/server-statefulset.bats'

Please upgrade Helm version in vault-helm-test images used by CI to more recent version.

[tvoran]

Fixed by #543