Add optional postgres 18 upgrade to chart

[madhav165]

✨ Feature / Enhancement PR

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🚀 Summary (1-2 sentences)

What does this PR add or change?
Adds optional sections to helm chart along with necessary jobs to the templates folder to accomplish a postgres 17 to 18 upgrade on a live database.

By default, the upgrade is disabled.

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🧪 Checks

• make lint passes
• make test passes

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📓 Notes (optional)

Design sketch, screenshots, or extra context.

Upgrade process from docs/docs/postgres-upgrade-process.md below.

This guide explains how to upgrade PostgreSQL from version 17 to 18 in the MCP Context Forge Helm chart with automated backup and restore to MinIO.

Prerequisites

Before proceeding with the upgrade, ensure:

• You have a running installation with PostgreSQL 17
• You have kubectl and helm access to your cluster
• You have sufficient disk space for backup operations
• You can accept brief downtime during the upgrade process

Upgrade Process

The upgrade process occurs in stages and requires two separate Helm operations:

Stage 1: Enable MinIO for Backup Storage

First, you need to ensure MinIO is deployed and running to store the database backup:

# Update your my-values.yaml to enable MinIO
helm upgrade --install mcp-stack ./charts/mcp-stack \
  --namespace mcp \
  --create-namespace \
  -f my-values.yaml \
  --wait --timeout 30m

Or directly set MinIO to enabled:

helm upgrade --install mcp-stack ./charts/mcp-stack \
  --namespace mcp \
  --create-namespace \
  -f my-values.yaml \
  --set minio.enabled=true \
  --wait --timeout 30m

Stage 2: Perform the PostgreSQL Upgrade with Backup

Once MinIO is running, proceed with the actual PostgreSQL upgrade:

1. Update your values file to configure the upgrade:

# In your my-values.yaml
postgres:
  upgrade:
    enabled: true              # Enable the PostgreSQL upgrade process
    targetVersion: "18"        # Target PostgreSQL version (18)
    backupCompleted: false     # Set to false to initiate backup process

2. Run the upgrade command:

helm upgrade --install mcp-stack ./charts/mcp-stack \
  --namespace mcp \
  -f my-values.yaml \
  --wait --timeout 30m

This will:

• Run a pre-upgrade hook to backup PostgreSQL 17 data to MinIO
• Upgrade the PostgreSQL deployment to version 18
• Restore data from the backup during PostgreSQL 18 initialization

Stage 3: Verify the Upgrade

After the upgrade completes, verify that everything is working:

# Check that all pods are running
kubectl get pods -n mcp

# Check PostgreSQL logs
kubectl logs -n mcp deployment/mcp-stack-postgres

# Verify the PostgreSQL version
kubectl exec -n mcp deployment/mcp-stack-postgres -- psql -U admin -c "SELECT version();"

Rollback Process

If something goes wrong and you need to rollback:

1. Set postgres.upgrade.enabled: false and postgres.upgrade.targetVersion: "17" in your values file
2. Run helm upgrade with the changes
3. The deployment will revert to PostgreSQL 17

Troubleshooting

Backup Job Fails

If the backup job fails, check the logs:

kubectl logs -n mcp -l app.kubernetes.io/component=postgres-backup

PostgreSQL Pod Stuck in CrashLoopBackOff

This usually indicates the data directory compatibility issue. Make sure:

• MinIO is accessible and running
• The backup file exists in MinIO
• The PVC has compatible ownership/perms

MinIO Not Starting

Ensure your storage class settings match existing PVCs:

kubectl describe pvc -n mcp

Configuration Reference

Upgrade Parameters

Parameter	Description	Default
postgres.upgrade.enabled	Enable the PostgreSQL upgrade process	false
postgres.upgrade.targetVersion	Target PostgreSQL version (currently supports "18")	"18"
postgres.upgrade.backupCompleted	Internal flag - set to false to trigger backup	false
minio.enabled	Enable MinIO for backup storage	true (recommended for upgrades)

Storage Configuration

When upgrading with existing PVCs, make sure to maintain the same storage class:

postgres:
  persistence:
    storageClassName: "same-as-existing-pvc"  # Match existing PVC
    size: "same-as-existing-pvc"              # Match existing PVC

Important Notes

• Backup Required: The upgrade process automatically creates a backup before upgrading
• Data Safety: Data is preserved during the upgrade process via the backup/restore mechanism
• Downtime: Expect brief downtime during the upgrade as PostgreSQL restarts
• PVC Compatibility: The PVC will be reused but the data will be migrated through the backup/restore process
• MinIO Required: MinIO must be enabled and operational for the upgrade to work

Cleanup After Successful Upgrade

Once you've verified the upgrade was successful:

1. Optionally set postgres.upgrade.backupCompleted: true to prevent the backup job from running in future upgrades
2. Clean up old backup files from MinIO if needed
3. Update your documentation to reflect the new PostgreSQL version