add possibillity to use imagePullSecrets

[rwaffen]

Add imagePullSecrets to pull images from private registries.
Does not manage the secret itself. only use existing secrets.

First setup control plane, maybe with errors because coredns/kube-proxy cannot be deployed. Then create the secret. Images should then be pulled automatically.

---
k8s::server::resources::image_pull_secrets:
  - name: my-private-registry-secret

[rwaffen]

hmm do not understand how the tests work. simply adding imagePullSecrets to the content yaml of kube-proxy does not work. and keys with undef values shouldn't end up in the resource and be filtered. i only know it like this from other modules 🤔

[ananace]

The tests are verifying the Puppet-generated Kubernetes resources against the fixtures under spec/fixtures/files/resources/kube-proxy{,-older}.yaml, and your change would modify the generated result - it'd add an imagePullSecrets: null to the container definition.

Undefs aren't fully filtered, since they need to go through to work with the merge patch strategy

[rwaffen]

🤦 oh. i found this yaml yesterday, but i thought (because of the error output) i have to write imagePullSecrets: nil but it's null. With null it works.

[ananace]

It feels like splatting/merging the value - after removing undef - into the pod hash might make the result a little nicer, but that's rather nitpicky of me and definitely not a requirement as long as Kubernetes is happy with getting a literal null instead of it not being defined or the empty array.