Add volume mounts to Flagger helm chart

[Jaxwood]

Describe the feature

Support for volume mounts in Flagger helm chart.

What problem are you trying to solve?

I would like to have the ability to define volumeMounts in the deployment manifest.

Currently the helm chart only supports using the additionalVolumes value in the values file.

You can't define volume mounts that uses the volumes you define.

Proposed solution

Add additionalVolumeMounts to the Flagger helm chart values file.

In the deployment template use that value when rendering the manifest.

Any alternatives you've considered?

Patch the deployment manifest using Kustomize.

Is there another way to solve this problem that isn't as good a solution?

I could use Kustomize to patch the deployment. In our case we are using Flux with HelmReleases and would prefer to keep things similar.