Add Pod Disruption Budget support to Trino chart

[Kab1r]

This commit adds Pod Disruption Budget (PDB) configuration options to the Trino Helm chart, bringing it to feature parity with the gateway chart which already has PDB support.

Changes

New Templates

• Added poddisruptionbudget-coordinator.yaml to manage coordinator pod disruptions
• Added poddisruptionbudget-worker.yaml to manage worker pod disruptions
  • Worker PDB is only created when server.workers > 0 (not in single-node mode)

Configuration

• Added coordinator.podDisruptionBudget configuration section in values.yaml

  • Supports both minAvailable and maxUnavailable strategies
  • Default is empty (no PDB created) for backward compatibility

• Added worker.podDisruptionBudget configuration section in values.yaml

  • Supports both minAvailable and maxUnavailable strategies
  • Default is empty (no PDB created) for backward compatibility

Benefits

Pod Disruption Budgets help maintain application availability during voluntary disruptions such as:

• Node maintenance and upgrades
• Cluster autoscaling operations
• Rolling updates of the cluster

For Trino specifically:

• Coordinator PDB: Ensures the coordinator remains available during disruptions, preventing complete query processing outages
• Worker PDB: Controls the rate at which workers can be disrupted, maintaining query processing capacity

Usage Examples

# Ensure at least 1 coordinator is always available
coordinator:
  podDisruptionBudget:
    minAvailable: 1

# Allow at most 1 worker to be unavailable at a time
worker:
  podDisruptionBudget:
    maxUnavailable: 1

Testing

Verified that:

• Templates render correctly with various PDB configurations
• PDBs are not created when not configured (backward compatible)
• Worker PDB is correctly omitted in single-node mode
• Label selectors properly match coordinator and worker pods

🤖 Generated with Claude Code

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[nineinchnick]

Set these values in the complete values test, so we know the chart renders correctly.