New to KubeDB? Please start here.
This is an Enterprise-only feature. Please install
KubeDB Enterprise Edition to try this feature.
Restart MongoDB
KubeDB supports restarting the MongoDB database via a MongoDBOpsRequest. Restarting is useful if some pods are got stuck in some phase, or they are not working correctly. This tutorial will show you how to use that.
Before You Begin
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At first, you need to have a Kubernetes cluster, and the kubectl command-line tool must be configured to communicate with your cluster. If you do not already have a cluster, you can create one by using kind.
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Now, install KubeDB cli on your workstation and KubeDB operator in your cluster following the steps here.
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To keep things isolated, this tutorial uses a separate namespace called demo throughout this tutorial.
$ kubectl create ns demo
namespace/demo created
Note: YAML files used in this tutorial are stored in docs/examples/mongodb folder in GitHub repository kubedb/docs.
Deploy MongoDB
In this section, we are going to deploy a MongoDB database using KubeDB.
apiVersion: kubedb.com/v1alpha2
kind: MongoDB
metadata:
name: mongo
namespace: demo
spec:
version: "4.4.6"
replicaSet:
name: "replicaset"
podTemplate:
spec:
resources:
requests:
cpu: "300m"
memory: "300Mi"
replicas: 2
storageType: Durable
storage:
storageClassName: "standard"
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 1Gi
terminationPolicy: WipeOut
arbiter: {}
hidden:
replicas: 2
storage:
storageClassName: "standard"
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 2Gi
spec.replicaSet represents the configuration for replicaset.
name denotes the name of mongodb replicaset.
spec.replicas denotes the number of general members in rs0 mongodb replicaset.spec.podTemplate denotes specifications of all the 3 general replicaset members.spec.ephemeralStorage holds the emptyDir volume specifications. This storage spec will be passed to the StatefulSet created by KubeDB operator to run database pods. So, each members will have a pod of this ephemeral storage configuration.spec.arbiter denotes arbiter-node spec of the deployed MongoDB CRD.spec.hidden denotes hidden-node spec of the deployed MongoDB CRD.
Let’s create the MongoDB CR we have shown above,
$ kubectl create -f https://github.com/kubedb/docs/raw/v2023.01.31/docs/examples/mongodb/restart/mongo.yaml
mongodb.kubedb.com/mongo created
Apply Restart opsRequest
apiVersion: ops.kubedb.com/v1alpha1
kind: MongoDBOpsRequest
metadata:
name: restart
namespace: demo
spec:
type: Restart
databaseRef:
name: mongo
readinessCriteria:
oplogMaxLagSeconds: 10
objectsCountDiffPercentage: 15
timeout: 3m
apply: Always
spec.type specifies the Type of the ops Requestspec.databaseRef holds the name of the MongoDB database. The db should be available in the same namespace as the opsRequest- The meaning of
spec.readinessCriteria, spec.timeout & spec.apply fields will be found here
Note: The method of restarting the standalone & sharded db is exactly same as above. All you need, is to specify the corresponding MongoDB name in spec.databaseRef.name section.
Let’s create the MongoDBOpsRequest CR we have shown above,
$ kubectl create -f https://github.com/kubedb/docs/raw/v2023.01.31/docs/examples/mongodb/restart/ops.yaml
mongodbopsrequest.ops.kubedb.com/restart created
Now the Ops-manager operator will first restart the general secondary pods, then serially the arbiters, the hidden nodes, & lastly will restart the Primary of the database.
$ kubectl get mgops -n demo
NAME TYPE STATUS AGE
restart Restart Successful 10m
$ kubectl get mgops -n demo -oyaml restart
apiVersion: ops.kubedb.com/v1alpha1
kind: MongoDBOpsRequest
metadata:
annotations:
kubectl.kubernetes.io/last-applied-configuration: |
{"apiVersion":"ops.kubedb.com/v1alpha1","kind":"MongoDBOpsRequest","metadata":{"annotations":{},"name":"restart","namespace":"demo"},"spec":{"apply":"Always","databaseRef":{"name":"mongo"},"readinessCriteria":{"objectsCountDiffPercentage":15,"oplogMaxLagSeconds":10},"timeout":"3m","type":"Restart"}}
creationTimestamp: "2022-10-31T08:54:45Z"
generation: 1
name: restart
namespace: demo
resourceVersion: "738625"
uid: 32f6c52f-6114-4e25-b3a1-877223cf7145
spec:
apply: Always
databaseRef:
name: mongo
readinessCriteria:
objectsCountDiffPercentage: 15
oplogMaxLagSeconds: 10
timeout: 3m
type: Restart
status:
conditions:
- lastTransitionTime: "2022-10-31T08:54:45Z"
message: MongoDB ops request is restarting the database nodes
observedGeneration: 1
reason: Restart
status: "True"
type: Restart
- lastTransitionTime: "2022-10-31T08:57:05Z"
message: Successfully Restarted ReplicaSet nodes
observedGeneration: 1
reason: RestartReplicaSet
status: "True"
type: RestartReplicaSet
- lastTransitionTime: "2022-10-31T08:57:05Z"
message: Successfully restarted all nodes of MongoDB
observedGeneration: 1
reason: Successful
status: "True"
type: Successful
observedGeneration: 1
phase: Successful
Cleaning up
To cleanup the Kubernetes resources created by this tutorial, run:
kubectl delete mongodbopsrequest -n demo restart
kubectl delete mongodb -n demo mongo
kubectl delete ns demo
Next Steps
