(DOCSP-32662) Adds docs for resizing PVC resources. (#1380)

Author: erabil-mdb

docs/resize-pvc.md

@@ -0,0 +1,101 @@
+# Resize PVC Resources #
+
+Resizing the [Persistent Volume Claim (PVC)](https://kubernetes.io/docs/concepts/storage/persistent-volumes/) resources for your Community Kubernetes Operator replica sets using the [StatefulSet](https://kubernetes.io/docs/concepts/workloads/controllers/statefulset/) is [not yet possible](https://github.com/kubernetes/enhancements/pull/3412). Instead, follow these steps to resize the PVC resource for each replica set and recreate the StatefulSet.
+
+1. Enable your storage provisioner to allow volume expansion by setting `allowVolumeExpansion` in the [StorageClass](https://kubernetes.io/docs/concepts/storage/storage-classes/) to `true`. For example:
+
+   ```
+   kubectl patch storageclass/<my-storageclass> --type='json' -p='[{"op": "add", "path": "/allowVolumeExpansion", "value": true }]'
+   ```
+
+1. If you don't already have a `MongoDBCommunity` resource with custom storage specified, create one. For example:
+
+   ```yaml
+   ---
+   apiVersion: mongodbcommunity.mongodb.com/v1
+   kind: MongoDBCommunity
+   metadata:
+     name: example-mongodb
+   spec:
+     members: 3
+     type: ReplicaSet
+     version: "6.0.5"
+     statefulSet:
+       spec:
+         volumeClaimTemplates:
+           - metadata:
+               name: data-volume
+             spec:
+               resources:
+                 requests:
+                   storage: 50Gi
+   ...
+   ```
+
+1. Patch the PVC resource for each replica set.
+
+   ```
+   kubectl patch pvc/"data-volume-<my-replica-set>-0" -p='{"spec": {"resources": {"requests": {"storage": "100Gi"}}}}'
+   kubectl patch pvc/"data-volume-<my-replica-set>-1" -p='{"spec": {"resources": {"requests": {"storage": "100Gi"}}}}'
+   kubectl patch pvc/"data-volume-<my-replica-set>-2" -p='{"spec": {"resources": {"requests": {"storage": "100Gi"}}}}'
+   ```
+
+1. Scale the Community Kubernetes Operator to `0`.
+
+   ```
+   kubectl scale deploy mongodb-kubernetes-operator --replicas=0
+   ```
+
+1. Remove the StatefulSet without removing the Pods.
+
+   ```
+   kubectl delete sts --cascade=orphan <my-replica-set>
+   ```
+
+1. Remove the `MongoDBCommunity` resource without removing the Pods.
+
+   ```
+   kubectl delete mdbc --cascade=orphan <my-replica-set>
+   ```
+
+1. Scale the Community Kubernetes Operator to `1`.
+
+   ```
+   kubectl scale deploy mongodb-kubernetes-operator --replicas=1
+   ```
+
+1. Add your new storage specifications to the `MongoDBCommunity` resource. For example:
+
+   ```yaml
+   ---
+   apiVersion: mongodbcommunity.mongodb.com/v1
+   kind: MongoDBCommunity
+   metadata:
+     name: example-mongodb
+   spec:
+     members: 3
+     type: ReplicaSet
+     version: "6.0.5"
+     statefulSet:
+       spec:
+         volumeClaimTemplates:
+           - metadata:
+               name: data-volume
+             spec:
+               resources:
+                 requests:
+                   storage: 100Gi
+   ...
+   ```
+
+1. Reapply the `MongoDBCommunity` resource. For example:
+
+   ```
+   kubectl apply -f PATH/TO/<MongoDBCommunity-resource>.yaml
+   ```
+
+1. If your storage provisioner doesn't support online expansion, restart the Pods.
+
+   ```
+   kubectl rollout restart sts <my-replica-set>
+   ```