Deployments using multiple workers in a single Worker Pool acquire different workers when packages overlap or subsequent steps do not use packages.

[IsaacCalligeros95]

Severity

Low, Sev 3

Version

All

Latest Version

I could reproduce the problem in the latest build

What happened?

Our docs spell out how Worker Selection works. In reality it looks like there's quite a few discrepancies in the actual behaviour and some room for improvement. There's some comments in the RequiredPackageListBuilder that call this out

        // We want to try to ensure actions which require the same package run on the same worker, to minimize package transfers.
        // This is currently pretty naive. It ignores:
        // - package versions
        // - some packages won't be acquired
        // - it is only using the first package which will be acquired in the case of actions with multiple packages
        // But this isn't functionality we advertise publicly, and it should cover the majority of cases.

The simplest case here is a deployment process with one worker pool, two steps (Run a Script), where the first uses a package and the other is an inline script. Since the packageId is a part of the Worker Lease Key, the second step will require a new worker. We should be able to fine tune this logic.

These docs also call out Reference Packages and reference package ordering. The WorkerLeaseFactory GetOrLeasePackageWorker only takes a single PackageId, which is then used in the worker lease key. The key is just a concatenation of the WorkerPoolId and the PackageId. From this it appears that Reference packages are completely ignored in this process

Containers and Execution images are another area to look into.

Reproduction

• Create a Worker Pool with 2 workers.
• Create two steps Run a Script steps, the first will use a package reference and the second will be an Inline Script.
• Depending on environment variables the project variables Octopus.Acquire.MaxParallelism and Octopus.Action.MaxParallelism may be required.
• Deploy -> Two workers will be selected
  

Error and Stacktrace

NA

More Information

No response

Workaround

No response

[Octobob]

🎉 The fix for this issue has been released in:

Release stream	Release
2024.3	2024.3.4888
2024.4+	all releases