Addon Discovery PoC

[njhale]

Overview

This is an attempt to port the addon discovery PoC demoed at the working group before the holidays. The primary goal is to see if we like this approach for tracking addon state.

Summary

addon-discovery identifies a cluster addon as a set of component Kubernetes resources selected by a label unique to that addon. It introduces a cluster-scoped Addon resource that surfaces:

• info about the addon
• the label selector used to gather its components
• a set of status enriched references to its components
• top-level conditions that summarize any abnormal state (Future Work)

Similar Operators

SIG Apps has an Application CRD with some overlapping features. A demo of addon-discovery to the SIG didn't produce strong feedback against or for. A follow-up is pending.

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[njhale]

This falls down when GVKs are removed from API discovery (e.g. a CRD is deleted). I would like this to play nice with controller-runtime abstractions, but that might not be possible. Any ideas?

[stealthybox]

@njhale Is the idea that the Informer is specific to a single or multiple GVKs?
Do you have ideas on how stopping it could be addressed?

[njhale]

@stealthybox In abstract, the idea is to provide a single event source that emits resources for all GVKs available in API discovery (for each point in time). There's also an additional requirement that this event source populates controller-runtime's client cache. Effectively, this implementation fans-in multiple informers to achieve this.

Do you have ideas on how stopping it could be addressed?

There's a controller-runtime issue and a PR that addresses this directly, though it seems like it's quickly becoming a broader conversation involving apimachinery.

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/lifecycle stale

[njhale]

/remove-lifecycle stale

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@fejta-bot: Closed this PR.

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