Configurable MaxConcurrentReconciles

[vaspahomov]

Why we need this PR

Default value for controller-manager for MaxConcurrentReconciles is 1. If we are going to start n parallel NodeMaintenances at the same time. We'll handle last one after n * d time. Where d is duration of reconcile. In current model the longest reconcile is more then 30s

That means - if we are starting ~50 parallel NodeMaintenances and each of them are failed to finish immediately (some blocking PDB exists) we we'll came up with the last one only after ~30mins.

Changes made

Added cli arg to override MaxConcurrentReconciles

Which issue(s) this PR fixes

Test plan

Summary by CodeRabbit

• New Features
  • Added a command-line option to control the maximum number of concurrent reconciliation processes for node maintenance.
• Improvements
  • Enhanced configurability of node maintenance operations by allowing users to set concurrency limits.

[openshift-ci[bot]]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: vaspahomov Once this PR has been reviewed and has the lgtm label, please assign clobrano for approval. For more information see the Code Review Process.

The full list of commands accepted by this bot can be found here.

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[coderabbitai[bot]]

Walkthrough

A new configuration option for maximum concurrent reconciles was introduced for the NodeMaintenanceReconciler. This includes adding a struct field, updating the controller setup to use this concurrency limit, and exposing a command-line flag to configure it. Test setup is also updated to initialize this field.

Changes

File(s)	Change Summary
controllers/nodemaintenance_controller.go	Added MaxConcurrentReconciles field to reconciler struct, updated controller builder to use it, and imported required package.
main.go	Added max-concurrent-reconciles flag, passed value to reconciler struct, and adjusted formatting.
controllers/controllers_suite_test.go	Initialized MaxConcurrentReconciles to 1 in test reconciler setup.

Sequence Diagram(s)

sequenceDiagram
    participant User
    participant Main
    participant NodeMaintenanceReconciler
    participant ControllerRuntime

    User->>Main: Start application with flags
    Main->>Main: Parse max-concurrent-reconciles flag
    Main->>NodeMaintenanceReconciler: Initialize with MaxConcurrentReconciles value
    NodeMaintenanceReconciler->>ControllerRuntime: SetupWithManager (with MaxConcurrentReconciles)
    ControllerRuntime-->>NodeMaintenanceReconciler: Controller runs with specified concurrency

Poem

In the warren, code hops anew,
Concurrency capped, just one will do.
A flag for the keepers, so clever and bright,
Now reconciles march, one per night.
With options set and tests aligned,
The rabbits rejoice—control refined!
🐇✨

✨ Finishing Touches

• [ ] 📝 Generate Docstrings

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[openshift-ci[bot]]

Hi @vaspahomov. Thanks for your PR.

I'm waiting for a medik8s member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

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Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository.

[slintes]

some first thoughts...

• I don't feel comfortable adding parallelism to the reconciler without any test code
• We should do something about the logger, which is a field of the reconciler, and being overwritten at the beginning of each reconcile. Probably should not be part of the reconciler anymore. Also, the CR being processed need to be added to the logger, so it's logged in every log statement
• The lease manager should not be an issue on a quick look

[slintes]

@razo7 @mshitrit WDYT?

[razo7]

I agree that test code is essential here to verify that nothing is messed up for concurrent NMO reconciles

[razo7]

/test 4.18-openshift-e2e