New to KubeDB? Please start here.
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
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.
Now, install KubeDB cli on your workstation and KubeDB operator in your cluster following the steps here.
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: "4.4.26"
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/v2024.3.16/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/v2024.3.16/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
