Handle existingClaim for storage conf

[jusabatier]

This PR add the ability to provide the name of an existing PVC to use for persistence.

Here I use LongHorn to manage PV/PVC, so I need this ability if I want to setup persistence.

[edevosc2c]

What's special about your setup that wouldn't work with the already available parameters for creating a PVC?

We provide the ability to:

• specify the storageclass per application: https://github.com/georchestra/helm-georchestra/blob/main/values.yaml#L233 (it's only documented in geoserver section but it works for all other applications)
• specify the size per application: https://github.com/georchestra/helm-georchestra/blob/main/values.yaml#L236
• specify the accessmode per application: https://github.com/georchestra/helm-georchestra/blob/main/values.yaml#L234
• specify the accessmode globally: https://github.com/georchestra/helm-georchestra/blob/main/values.yaml#L255
• specify the storageclass globally: https://github.com/georchestra/helm-georchestra/blob/main/values.yaml#L254

[jusabatier]

If I use storageclass, the pvc will be created in longhorn with a random name at the pod's startup, and deleted when it terminate.

The most common method to work with longhorn is to use existingClaims to provide the PVC to use.

[edevosc2c]

the pvc will be created in longhorn with a random name at the pod's startup

The PVC name is not random, it's actually generated here: https://github.com/georchestra/helm-georchestra/blob/main/templates/geoserver/geoserver-geodata-pvc.yaml#L7

But the PV name is random, yes that's a feature. But you should get the same result if you create a PVC "normally", that's how Kubernetes works with dynamically provisionned PVC.

and deleted when it terminate

That's not true, we have recently configured helm.sh/resource-policy: true so that if you delete the helm chart then the PVC are kept.

And about keeping the PV in case you delete the PVC, you need to create a storageclass with the parameter reclaimPolicy: Retain.

I fail to see how using an external PVC will be different from letting the helm chart manage it for you. If you have mistakenly deleted a PVC, then you can switch it back in state from "Released" to "Available" using this method: https://stackoverflow.com/a/59406641 and then assign its "random name" in pv_name parameter: https://github.com/georchestra/helm-georchestra/blob/main/values.yaml#L231

---

I'm available on georchestra matrix if you want to further discuss this.