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Version: release-0.9

Create and connect to a MySQL cluster

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

Create a MySQL cluster​

Before you start​

  • Install kbcli.

  • Install KubeBlocks.

  • Make sure the MySQL Addon is enabled. The MySQL Addon is installed and enabled by KubeBlocks by default. If you disable it when installing KubeBlocks, enable it first.

    kubectl get addons.extensions.kubeblocks.io mysql
    >
    NAME    TYPE   VERSION   PROVIDER   STATUS    AGE
    mysql   Helm                        Enabled   27h

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

    Make sure the mysql cluster definition is installed.

    kubectl get clusterdefinition mysql
    >
    NAME             TOPOLOGIES   SERVICEREFS   STATUS      AGE
    mysql                                       Available   85m

    View all available versions for creating a cluster.

    kubectl get clusterversions -l clusterdefinition.kubeblocks.io/name=mysql
    >
    NAME           CLUSTER-DEFINITION   STATUS      AGE
    mysql-5.7.44   mysql                Available   27h
    mysql-8.0.33   mysql                Available   27h
    mysql-8.4.2    mysql                Available   27h

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

    kubectl create namespace demo

Create a cluster​

KubeBlocks supports creating two types of MySQL clusters: Standalone and Replication Cluster. 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 Replication Cluster, which creates a cluster with two replicas. To ensure high availability, all replicas are distributed on different nodes by default.

  1. Create a MySQL cluster.

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

    If you only have one node for deploying a Replication Cluster, set spec.affinity.topologyKeys as null. 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/v1alpha1
    kind: Cluster
    metadata:
      name: mycluster
      namespace: demo
    spec:
      clusterDefinitionRef: mysql
      clusterVersionRef: mysql-8.0.33
      terminationPolicy: Delete
      affinity:
        podAntiAffinity: Preferred
        topologyKeys:
        - kubernetes.io/hostname
      tolerations:
        - key: kb-data
          operator: Equal
          value: 'true'
          effect: NoSchedule
      componentSpecs:
      - name: mysql
        componentDefRef: mysql
        enabledLogs:
        - error
        - slow
        disableExporter: true
        replicas: 2
        serviceAccountName: kb-mycluster
        resources:
          limits:
            cpu: '0.5'
            memory: 0.5Gi
          requests:
            cpu: '0.5'
            memory: 0.5Gi
        volumeClaimTemplates:
        - name: data
          spec:
            accessModes:
            - ReadWriteOnce
            resources:
              requests:
                storage: 20Gi
    EOF
    FieldDefinition
    spec.clusterDefinitionRefIt specifies the name of the ClusterDefinition for creating a specific type of cluster.
    spec.clusterVersionRefIt is the name of the cluster version CRD that defines the cluster version.
    spec.terminationPolicyIt is the policy of cluster termination. The default value is Delete. Valid values are DoNotTerminate, Delete, WipeOut. For the detailed definition, you can refer to Termination Policy.
    spec.affinityIt defines a set of node affinity scheduling rules for the cluster's Pods. This field helps control the placement of Pods on nodes within the cluster.
    spec.affinity.podAntiAffinityIt specifies the anti-affinity level of Pods within a component. It determines how pods should spread across nodes to improve availability and performance.
    spec.affinity.topologyKeysIt represents the key of node labels used to define the topology domain for Pod anti-affinity and Pod spread constraints.
    spec.tolerationsIt is an array that specifies tolerations attached to the cluster's Pods, allowing them to be scheduled onto nodes with matching taints.
    spec.componentSpecsIt is the list of components that define the cluster components. This field allows customized configuration of each component within a cluster.
    spec.componentSpecs.componentDefRefIt is the name of the component definition that is defined in the cluster definition and you can get the component definition names with kubectl get clusterdefinition mysql -o json | jq '.spec.componentDefs[].name'.
    spec.componentSpecs.nameIt specifies the name of the component.
    spec.componentSpecs.disableExporterIt defines whether the monitoring function is enabled.
    spec.componentSpecs.replicasIt specifies the number of replicas of the component.
    spec.componentSpecs.resourcesIt specifies the resource requirements of the component.

    For the details of different parameters, you can refer to API docs.

    Run the following commands to see the created MySQL 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   mysql                mysql-8.0.30      Delete               Running   6m53s

Connect to a MySQL Cluster​

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

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

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

  1. Run the command below to get the username and password for the kubectl exec command.

    kubectl get secrets mycluster-conn-credential -n demo -o jsonpath='{.data.username}' | base64 -d
    >
    root
    kubectl get secrets mycluster-conn-credential -n demo -o jsonpath='{.data.password}' | base64 -d
    >
    b8wvrwlm

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

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

    mysql -u root -p b8wvrwlm

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