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Create and connect to a MongoDB cluster

This tutorial shows how to create and connect to a MongoDB cluster.

Create a MongoDB cluster​

Before you start​

  • Install kbcli if you want to create and connect a MySQL cluster by kbcli.

  • Install KubeBlocks.

  • Make sure the MongoDB Addon is enabled. If this addon is not enabled, enable it first.

    kubectl get addons.extensions.kubeblocks.io mongodb
    >
    NAME      TYPE   VERSION   PROVIDER   STATUS    AGE
    mongodb   Helm                        Enabled   23m

  • View all the database types and versions available for creating a cluster.

    kubectl get clusterdefinition mongodb
    >
    NAME      TOPOLOGIES   SERVICEREFS   STATUS      AGE
    mongodb                              Available   23m
    kubectl get clusterversions -l clusterdefinition.kubeblocks.io/name=mongodb

  • To keep things isolated, create a separate namespace called demo throughout this tutorial.

    kubectl create namespace demo
    >
    namespace/demo created

Create a cluster​

KubeBlocks supports creating two types of MongoDB clusters: Standalone and ReplicaSet. Standalone only supports one replica and can be used in scenarios with lower requirements for availability. For scenarios with high availability requirements, it is recommended to create a ReplicaSet, which creates a cluster with two replicas to support automatic failover. To ensure high availability, all replicas are distributed on different nodes by default.

  1. Create a MongoDB Standalone.

    KubeBlocks implements a Cluster CRD to define a cluster. Here is an example of creating a MongoDB Standalone.

    If you only have one node for deploying a ReplicaSet Cluster, configure the cluster affinity by setting spec.schedulingPolicy or spec.componentSpecs.schedulingPolicy. For details, you can refer to the API docs. But for a production environment, it is not recommended to deploy all replicas on one node, which may decrease the cluster availability.

    cat <<EOF | kubectl apply -f -
    apiVersion: apps.kubeblocks.io/v1
    kind: Cluster
    metadata:
      name: mycluster
      namespace: demo
    spec:
      terminationPolicy: Delete
      clusterDef: mongodb
      topology: replicaset
      componentSpecs:
        - name: mongodb
          serviceVersion: "6.0.16"
          replicas: 3
          resources:
            limits:
              cpu: '0.5'
              memory: 0.5Gi
            requests:
              cpu: '0.5'
              memory: 0.5Gi
          volumeClaimTemplates:
            - name: data
              spec:
                storageClassName: ""
                accessModes:
                  - ReadWriteOnce
                resources:
                  requests:
                    storage: 20Gi
    EOF
    FieldDefinition
    spec.terminationPolicyIt is the policy of cluster termination. Valid values are DoNotTerminate, Delete, WipeOut. For the detailed definition, you can refer to Termination Policy.
    spec.clusterDefIt specifies the name of the ClusterDefinition to use when creating a Cluster. Note: DO NOT UPDATE THIS FIELD. The value must be mongodb to create a MongoDB Cluster.
    spec.topologyIt specifies the name of the ClusterTopology to be used when creating the Cluster.
    spec.componentSpecsIt is the list of ClusterComponentSpec objects that define the individual Components that make up a Cluster. This field allows customized configuration of each component within a cluster.
    spec.componentSpecs.serviceVersionIt specifies the version of the Service expected to be provisioned by this Component. Valid options are: [4.0.28,4.2.24,4.4.29,5.0.28,6.0.16,7.0.1].
    spec.componentSpecs.disableExporterIt determines whether metrics exporter information is annotated on the Component's headless Service. Valid options are [true, false].
    spec.componentSpecs.replicasIt specifies the number of replicas of the component.
    spec.componentSpecs.resourcesIt specifies the resources required by the Component.
    spec.componentSpecs.volumeClaimTemplatesIt specifies a list of PersistentVolumeClaim templates that define the storage requirements for the Component.
    spec.componentSpecs.volumeClaimTemplates.nameIt refers to the name of a volumeMount defined in componentDefinition.spec.runtime.containers[*].volumeMounts.
    spec.componentSpecs.volumeClaimTemplates.spec.storageClassNameIt is the name of the StorageClass required by the claim. If not specified, the StorageClass annotated with storageclass.kubernetes.io/is-default-class=true will be used by default.
    spec.componentSpecs.volumeClaimTemplates.spec.resources.storageYou can set the storage size as needed.

    For more API fields and descriptions, refer to the API Reference.

    KubeBlocks operator watches for the Cluster CRD and creates the cluster and all dependent resources. You can get all the resources created by the cluster by running the command below.

    kubectl get all,secret,rolebinding,serviceaccount -l app.kubernetes.io/instance=mycluster -n demo

    Run the following command to view the created MongoDB cluster object.

    kubectl get cluster mycluster -n demo -o yaml

  2. Verify whether this cluster is created successfully.

    kubectl get cluster mycluster -n demo
    >
    NAME        CLUSTER-DEFINITION   VERSION           TERMINATION-POLICY   STATUS    AGE
    mycluster   mongodb              mongodb-5.0       Delete               Running   12m

Connect to a MongoDB Cluster​

You can use kubectl exec to exec into a Pod and connect to a database.

KubeBlocks operator has created a new Secret called mycluster-conn-credential to store the connection credential of the MongoDB cluster. This secret contains the following keys:

  • username: the root username of the MongoDB cluster.
  • password: the password of the root user.
  • port: the port of the MongoDB cluster.
  • host: the host of the MongoDB cluster.
  • endpoint: the endpoint of the MongoDB cluster and it is the same as host:port.

  1. Get the username and password to connect to this MongoDB cluster for the kubectl exec command.

    kubectl get secrets -n demo mycluster-conn-credential -o jsonpath='{.data.username}' | base64 -d
    >
    root

    kubectl get secrets -n demo mycluster-conn-credential -o jsonpath='{.data.password}' | base64 -d
    >
    266zfqx5

  2. Exec into the Pod mycluster-mongodb-0 and connect to the database using username and password.

    kubectl exec -ti -n demo mycluster-mongodb-0 -- bash

    root@mycluster-mongodb-0:/# mongo --username root --password 266zfqx5 --authenticationDatabase admin

For the detailed database connection guide, refer to Connect database.