Helm chart: add gateway.backend.imagePullSecrets

[maxime1907]

Proposal

Currently, dask-gateway retrieves images that are hosted on public registries.
This behavior is fine but if we want to use private registries, it is only possible through worker_extra_pod_config and scheduler_extra_pod_config.
I have then tought of a way to implement it properly without introducing any breaking change.

Implementation

• Add a KubeClusterConfig configuration field called image_pull_secrets that lets dask scheduler and worker pods to pull images from private registries.
• Change the helm chart to add support for the configuration field called image_pull_secrets thanks to the following field:
  • imagePullSecrets: Image pull secrets to access private registries

Behind the scene

From the user and dask operator POV, it doesn't have any impact on the current behavior of dask-gateway.

---

• EDIT by consideRatio: closes Helm chart: add imagePullSecrets for gateway.backend #583 as this is a duplicate PR.
• EDIT by consideRatio: closes Helm Chart: gateway.backend Missing "imagePullSecrets" #584

[maxime1907]

cc @consideRatio

[consideRatio]

Thanks @maxime1907! Note though that you have opened a PR, and there is already another PR about this opened.

As #583 currently doesn't have the key part of the PR, making the controller Python logic create the scheduler and worker pods based on the configuration. Let's go for getting this PR merged.

Ping @chadsr and @szachovy from #583.

[consideRatio]

Also, I see that there is descriptions in the schema file about tag, pullPolicy, or pullSecrets, could you delete the pullSecrets part as that is not correct and semi-related to this PR that implements the imagePullSecrets field?

[consideRatio]

With the suggested changes, this LGTM.

[consideRatio]

@maxime1907 I applied the change suggestions, if this looks good to you, let's go for a merge!

[maxime1907]

@maxime1907 I applied the change suggestions, if this looks good to you, let's go for a merge!

Thank you a lot!!
Yes you can merge like this 🙂

[consideRatio]

Thank you @maxime1907, @chadsr, and @szachovy for your contributions towards this!!! ❤️ 🎉 🌻