Ability to source secrets from file path

[cpboyd]

Use case: Vault sidecar injection e.g. https://www.vaultproject.io/docs/platform/k8s/injector/examples#environment-variable-example

Since the entrypoint is /chartmuseum, it's not possible to source as in Hashicorp's examples.

I've also attempted the following, but Kubernetes only seems to interpolate for variable names that have already been defined.

extraArgs:
  - --basic-auth-user=$(cat /vault/secrets/config | awk '{print $1}')
  - --basic-auth-pass=$(cat /vault/secrets/config | awk '{print $2}')

Maybe the optimal solution would be to simply allow a onStart script or something that happens before /chartmuseum starts, so that you could source the environment variables?

[cpboyd]

A workaround, for now, is

extraArgs:
  command: ['/bin/sh', '-c', 'source /vault/secrets/config && /chartmuseum']

Note: the default args don't seem to be passed to /chartmuseum via this method. As Chartmuseum's default port is 8080 anyway, this only really matters for local storage with --storage-local-rootdir={{ .Values.persistence.path }}