Resize Storage for One Database Resource

Create or identify a persistent custom resource.

Use an existing database resource or create a new one with persistent storage. Wait until the persistent volume gets to the Running state.

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apiVersion: mongodb.com/v1
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kind: MongoDB
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metadata:
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  name: <my-replica-set>
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spec:
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  members: 3
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  version: "4.4.0"
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  project: my-project
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  credentials: my-credentials
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  type: ReplicaSet
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  podSpec:
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    persistence:
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      single:
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        storage: "1Gi"

Insert data to the database that the resource serves.

1. Start mongo in the Kubernetes cluster.

   $kubectl exec -it <my-replica-set>-0 \
            /var/lib/mongodb-mms-automation/mongodb-linux-x86_64-4.4.0/bin/mongo

2. Insert data into the test database.

   <my-replica-set>:PRIMARY> use test
   switched to db test
   <my-replica-set>:PRIMARY> db.tmp.insertOne({"foo":"bar"})
   {
     "acknowledged" : true,
     "insertedId" : ObjectId("61128cb4a783c3c57ae5142d")
   }

Patch each persistence volume.

Invoke the following commands for the entire replica set:

kubectl patch pvc/"data-<my-replica-set>-0" -p='{"spec": {"resources": {"requests": {"storage": "2Gi"}}}}'
kubectl patch pvc/"data-<my-replica-set>-1" -p='{"spec": {"resources": {"requests": {"storage": "2Gi"}}}}'
kubectl patch pvc/"data-<my-replica-set>-2" -p='{"spec": {"resources": {"requests": {"storage": "2Gi"}}}}'

Wait until each Persistent Volume Claim gets to the following condition:

- lastProbeTime: null
  lastTransitionTime: "2019-08-01T12:11:39Z"
  message: Waiting for user to (re-)start a pod to finish file
           system resize of volume on node.
  status: "True"
  type: FileSystemResizePending

Remove the StatefulSets.

Delete a StatefulSet resource.

kubectl delete sts --cascade=false <my-replica-set>

Update the database resource with a new storage value.

1. Update the disk size. Open your preferred text editor and make changes similar to this example:

   Example

   To update the disk size of the replica set to 2 GB, change the storage value in database resource specification:

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   apiVersion: mongodb.com/v1
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   kind: MongoDB
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   metadata:
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     name: <my-replica-set>
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   spec:
   6
     members: 3
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     version: "4.4.0"
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     project: my-project
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     credentials: my-credentials
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     type: ReplicaSet
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     podSpec:
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       persistence:
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         single:
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           storage: "2Gi"

2. Recreate a StatefulSet resource with the new volume size.

   kubectl apply -f my-replica-set-vol.yaml

3. Wait until this StatefulSet achieves the Running state.

Update the pods in a rolling fashion.

Invoke the following command:

kubectl rollout restart sts <my-replica-set>

The new pods mount the resized volume.

Validate data exists on the updated Persistent Volume Claim.

If the Persistent Volumes were reused, the data that you inserted in Step 2 can be found on the databases stored in Persistent Volumes:

$ kubectl exec -it <my-replica-set>-1 \
          /var/lib/mongodb-mms-automation/mongodb-linux-x86_64-4.4.0/bin/mongo

<my-replica-set>:PRIMARY> use test
switched to db test
<my-replica-set>:PRIMARY> db.tmp.count()
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