feat(supervisor): add k8 worker pod priority class support

[NERLOE]

Add KUBERNETES_WORKER_PRIORITY_CLASS_NAME environment variable to allow configuring a priority class for task run pods in Kubernetes environments.

This addresses pod preemption issues in resource-constrained clusters, particularly in GKE Autopilot where low-priority pods can be preempted by system pods during scale-up operations.

Closes #2630

✅ Checklist

• I have followed every step in the contributing guide
• The PR title follows the convention.
• I ran and tested the code works

---

Testing

Added example configuration and tested assignment of priority class on our worker pods in our GKE Autopilot production cluster.

supervisor:
  extraEnvVars:
    - name: KUBERNETES_WORKER_PRIORITY_CLASS_NAME
      value: "trigger-task-runs"

extraManifests:
  - apiVersion: scheduling.k8s.io/v1
    kind: PriorityClass
    metadata:
      name: trigger-task-runs
    value: 100000
    globalDefault: false

Changelog

• Added: KUBERNETES_WORKER_PRIORITY_CLASS_NAME environment variable to apps/supervisor/src/env.ts
• Added: Support for priorityClassName in Kubernetes pod spec (apps/supervisor/src/workloadManager/kubernetes.ts)
• Enhancement: Worker pods can now be configured with priority classes to prevent preemption in resource-constrained environments
• Compatibility: Fully backward compatible - optional configuration with no breaking changes

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Screenshots

N/A - Infrastructure/backend change. Configuration can be verified via:

# Verify priority class is applied to new worker pods
kubectl get pods -n trigger -l app=task-run \
  -o custom-columns=NAME:.metadata.name,PRIORITY:.spec.priority,PRIORITY_CLASS:.spec.priorityClassName

Expected output after configuration:

NAME                               PRIORITY   PRIORITY_CLASS
runner-cmh4xxxxx                   100000     trigger-task-runs

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Walkthrough

This pull request extends the Kubernetes configuration schema by adding a new optional environment variable KUBERNETES_WORKER_PRIORITY_CLASS_NAME. The environment variable definition is added to the Env schema, and corresponding logic is implemented in the workload manager to conditionally include the priorityClassName field in pod specifications when this variable is defined. These changes introduce new configuration capability without modifying existing fields or control flow.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~8 minutes

The review scope is limited to two tightly-related files with homogeneous changes focused on a single feature. The modifications are straightforward: adding an optional schema field and implementing conditional logic to use it. No complex logic density, no structural refactoring, and minimal risk of unintended side effects on existing functionality.

Pre-merge checks and finishing touches

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	You can run @coderabbitai generate docstrings to improve docstring coverage.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title Check	✅ Passed	The PR title "feat(supervisor): add k8 worker pod priority class support" clearly and accurately describes the main change in the pull request. It follows the conventional commit format with a proper scope (supervisor) and concisely identifies the primary feature being added: Kubernetes worker pod priority class support. The title directly corresponds to the implementation of the new KUBERNETES_WORKER_PRIORITY_CLASS_NAME environment variable and its integration into the pod specification.
Linked Issues Check	✅ Passed	The implementation directly addresses all primary coding objectives from linked issue #2630. The changes add the KUBERNETES_WORKER_PRIORITY_CLASS_NAME environment variable configuration capability and modify the Kubernetes pod spec to conditionally include the priorityClassName field. This implementation allows operators to configure priority classes for task run pods to prevent preemption during cluster scale-up in resource-constrained environments like GKE Autopilot. The solution is backward compatible with no breaking changes, and the PR description demonstrates testing in a GKE Autopilot production cluster.
Out of Scope Changes Check	✅ Passed	All changes in this pull request are directly scoped to the objectives defined in linked issue #2630. The modifications are limited to two files: apps/supervisor/src/env.ts (adding the environment variable) and apps/supervisor/src/workloadManager/kubernetes.ts (using the variable in pod spec). No extraneous files were modified, no unrelated functionality was changed, and all changes are focused exclusively on implementing the priority class support feature for Kubernetes worker pods.
Description Check	✅ Passed	The PR description is comprehensive and follows the required template structure. It includes all essential sections: the issue reference (Closes #2630), a completed checklist confirming the contributing guide was followed and the code was tested, a detailed testing section with example configuration and kubectl verification commands, a thorough changelog section with specific file modifications, and an appropriate "N/A" note for screenshots with reasoning. The description provides clear context about the problem (pod preemption in GKE Autopilot) and demonstrates that the solution was tested in production.

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Files:

• apps/supervisor/src/env.ts
• apps/supervisor/src/workloadManager/kubernetes.ts

🧬 Code graph analysis (1)

apps/supervisor/src/workloadManager/kubernetes.ts (2)

apps/supervisor/src/env.ts (1)

• env (120-120)

apps/webapp/app/env.server.ts (1)

• env (1208-1208)

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🔇 Additional comments (2)

apps/supervisor/src/env.ts (1)

84-84: LGTM! Clean addition of optional priority class configuration.

The environment variable is correctly defined as optional, properly placed within the Kubernetes settings section, and follows the existing naming convention.

apps/supervisor/src/workloadManager/kubernetes.ts (1)

289-293: LGTM! Consistent implementation of optional priorityClassName.

The conditional spread pattern matches the existing approach for schedulerName and nodeSelector, ensuring the field is only included when configured. The Kubernetes API will handle validation of the priority class name at pod creation time, with errors properly caught and handled by the existing error handling logic.

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