feat(complex): Add possibility to use existent PVC in pods

[joli-sys]

Add Support for Shared PersistentVolumeClaims

Problem

When using AWS EFS with Kubernetes, each PVC creates a new access point with different POSIX users by default, preventing pods from seeing each other's data. This makes it impossible to share storage across multiple pods/components.

Solution

Added support for referencing existing PVCs using useExistingClaim option, allowing multiple components to share the same persistent storage.

Changes

Helm Chart Updates

1. templates/persistentvolumeclaim.yaml

   • Added conditional check to skip PVC creation when useExistingClaim: true
   • Maintains generic approach (no storage-specific assumptions)

2. templates/_pod.tpl

   • Updated volume reference to use existingClaimName when useExistingClaim is enabled
   • Falls back to component name for new PVCs

3. values.schema.json

   • Added useExistingClaim (boolean) property
   • Added existingClaimName (string) property

4. README.md

   • Added comprehensive "Persistent Volume Claims" section
   • Documented both creating new PVCs and using existing ones
   • Added examples and use cases

5. testing-values/values-pvc-efs-shared.yaml

   • Added example showing shared storage patterns