Complete Helm chart dev mode implementation from PR #47595 with NFS and hot-reload support

[Copilot]

Finish up the Helm chart implementation based on PR apache#47595

This PR implements dev mode support for the Airflow Helm chart to improve the Kubernetes development experience with automatic hot-reloading:

Plan:

• Add devMode configuration to chart/values.yaml
• Add devMode schema to chart/values.schema.json
• Add helper templates for code mounts in chart/templates/_helpers.yaml
• Create dev-mode-code-volume-claim.yaml for PVC
• Create dev-mode-code-pre-install-hook.yaml for initialization
• Update scheduler deployment to mount code PVC
• Update webserver deployment to mount code PVC (fix bug from PR)
• Update worker deployment to mount code PVC
• Update triggerer deployment to mount code PVC
• Update dag-processor deployment to mount code PVC
• Update api-server deployment to mount code PVC
• Add breeze k8s restart command
• Update breeze configuration files
• Test Helm chart validation
• Run code review and security checks
• Fix PVC creation timing issue
• Add NFS server for shared code access with ReadWriteMany
• Add --dev flag support for automatic hot-reloading

Validation Results:

• ✅ Helm lint passes successfully
• ✅ Templates render correctly with devMode enabled
• ✅ PVC now created as regular resource (not hook) before pre-install hook runs
• ✅ NFS server deployment and service created for shared code access
• ✅ Code volumes are mounted in all components with ReadWriteMany access mode
• ✅ --dev flag properly added to all Airflow components when devMode enabled
• ✅ Templates correctly exclude dev-mode resources when devMode.enabled=false
• ✅ PVC correctly skipped when existingClaim is specified
• ✅ Code review passed with 1 minor grammar fix applied
• ✅ CodeQL security scan completed with no issues

Changes:
The implementation adds:

• devMode.enabled flag to enable/disable dev mode (automatically enabled in breeze deploy)
• devMode.persistence configuration for PVC settings (size, storageClassName, existingClaim)
• NFS server deployment and service for shared code volume across all pods
• ReadWriteMany PVC backed by NFS for concurrent code access
• Mounts for airflow-core, airflow-ctl, and task-sdk directories with readOnly access
• Pre-install hook to initialize code directories with proper error handling
• Automatic --dev flag added to all Airflow component commands when devMode is enabled:
  • scheduler: airflow scheduler --dev
  • webserver: airflow webserver --dev (Airflow <3.0)
  • workers: airflow celery worker --dev
  • triggerer: airflow triggerer --dev
  • dag-processor: airflow dag-processor --dev
  • api-server: airflow api-server --dev
• Fixed bug in webserver-deployment.yaml where it checked .Values.devMode.persistence.enabled instead of .Values.devMode.enabled
• Fixed timing issue: removed helm hooks from PVC so it's created as regular resource before hooks run
• breeze k8s restart command to restart specific or all airflow components
• Support for component-specific operations (all, scheduler, api-server, trigger, workers)
• Helm hook annotations for proper lifecycle management

Benefits:

• Significantly improves k8s test iteration process with automatic hot-reloading via --dev flag
• Shared code volume accessible by all pods simultaneously via NFS with ReadWriteMany
• Eliminates need to rebuild images for every code change
• Only requires image rebuild when dependencies change
• Code changes are automatically reloaded without manual intervention
• Reduces development time and feedback loops dramatically

Original prompt

Based on apache#47595 PR, checkout a new branch to finish up the Helm chart

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[jason810496]

@copilot I encounter "/opt/airflow/dags" not found error when deploy airflow, we need to ensure code PVC is already existed before we run the pre-install hook

[Copilot]

@copilot I encounter "/opt/airflow/dags" not found error when deploy airflow, we need to ensure code PVC is already existed before we run the pre-install hook

Fixed in commit 93abea8. The code PVC was incorrectly configured as a helm pre-install hook, which caused timing issues where the init-dev-code Job tried to mount the PVC before it was fully bound.

Changed the PVC to be a regular resource (like the logs PVC) by removing the helm.sh/hook annotations. Now the PVC is created and bound during the normal resource creation phase, before any pre-install hooks run. This ensures the PVC is ready when the init-dev-code Job executes.

Also added the existingClaim check to match the logs PVC pattern.

[github-actions]

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[jason810496]

@copilot

• add a new NFS Server setup for airflow_code_volume_claim with ReadWriteMany access when devMode.enabled
• remove reload_code breeze command
• add --dev flag for each Airflow components if when devMode.enabled

[Copilot]

@copilot

• add a new NFS Server setup for airflow_code_volume_claim with ReadWriteMany access when devMode.enabled...

Completed all requested changes in commit dc234f7:

1. ✅ Added NFS Server setup with deployment and service for airflow_code_volume_claim with ReadWriteMany access mode
2. ✅ Removed reload-code breeze command
3. ✅ Added --dev flag for all Airflow components when devMode.enabled:
   • scheduler: airflow scheduler --dev
   • webserver: airflow webserver --dev (Airflow <3.0)
   • workers: airflow celery worker --dev
   • triggerer: airflow triggerer --dev
   • dag-processor: airflow dag-processor --dev
   • api-server: airflow api-server --dev

The NFS server enables ReadWriteMany access so all pods can share the code volume for hot-reloading with the --dev flag.