nutanix-cloud-native / nutanix-cloud-native/cluster-api-runtime-extensions-nutanix

Implement idempotent patching in a helper package

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Dominant language
Go
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17
Forks
12
Avg merge
1d 10h
Merged PRs (30d)
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Description

Idempotence: An External Patch Extension must only return patches if changes to the templates are required, i.e. unnecessary patches when the template is already in the desired state must be avoided.
-- https://cluster-api.sigs.k8s.io/tasks/experimental-features/runtime-sdk/implement-topology-mutation-hook#patch-extension-guidelines

We want patches to be idempotent.

Right now, this burden is the individual patch handlers, namely, the Mutate method defined in the MetaMutator interface).

I think we should implement idempotent patching in a package that all handlers can use, for at least these reasons:

  1. Idempotence is hard to get right
  2. Idempotent patching can be implemented in a way that's not specific to any one handler

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  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start with the MetaMutator interface and its Mutate method in common/pkg/capi/clustertopology/handlers/mutation/meta.go, then review the existing patch handlers that implement it. Define a shared approach that returns patches only when templates differ from the desired state, and verify that handlers avoid unnecessary patches.

Written by the indexing model from the issue text.

Assessment

Tech stack
go
Domain
infrastructure
Issue type
Feature
Difficulty
5/5
Estimated time
Over a week
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
25/100

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