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

• Install KubeBlocks by kbcli or install KubeBlocks by Helm.

• Make sure the ApeCloud MySQL add-on is enabled.

  kbcli

  kbcli addon list
  >
  NAME                           TYPE   STATUS     EXTRAS         AUTO-INSTALL   INSTALLABLE-SELECTOR
  ...
  apecloud-mysql                 Helm   Enabled                   true
  ...

  kubectl

  kubectl get addons.extensions.kubeblocks.io apecloud-mysql
  >
  NAME             TYPE   STATUS    AGE
  apecloud-mysql   Helm   Enabled   61s

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

  kbcli

  kbcli clusterdefinition list
  
  kbcli clusterversion list

  kubectl

  Make sure the apecloud-mysql cluster definition is installed with kubectl get clusterdefinition apecloud-mysql.

  kubectl get clusterdefinition apecloud-mysql
  >
  NAME             MAIN-COMPONENT-NAME   STATUS      AGE
  apecloud-mysql   mysql                 Available   85m

  View all available versions for creating a cluster.

  kubectl get clusterversions -l clusterdefinition.kubeblocks.io/name=apecloud-mysql

• 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 RaftGroup 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 RaftGroup Cluster, which creates a cluster with three replicas. And to ensure high availability, all replicas are distributed on different nodes by default.

kbcli

Create a Standalone.

kbcli cluster create mysql <clustername>

Create a RaftGroup Cluster.

kbcli cluster create mysql --mode raftGroup <clustername>

If you only have one node for deploying a RaftGroup Cluster, set the availability-policy as none when creating a RaftGroup Cluster.

kbcli cluster create mysql --mode raftGroup --availability-policy none <clustername>

note

• In the production environment, it is not recommended to deploy all replicas on one node, which may decrease the cluster availability.

• Run the command below to view the flags for creating a MySQL cluster and the default values.

  kbcli cluster create mysql -h

kubectl

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

cat <<EOF | kubectl apply -f -
apiVersion: apps.kubeblocks.io/v1alpha1
kind: Cluster
metadata:
  name: mysql-cluster
  namespace: demo
spec:
  clusterDefinitionRef: apecloud-mysql
  clusterVersionRef: ac-mysql-8.0.30
  componentSpecs:
  - componentDefRef: mysql
    name: mysql
    replicas: 3
    resources:
      limits:
        cpu: "1"
        memory: 1Gi
      requests:
        cpu: "1"
        memory: 1Gi
    volumeClaimTemplates:
    - name: data
      spec:
        accessModes:
        - ReadWriteOnce
        resources:
          requests:
            storage: 20Gi
  terminationPolicy: Delete
EOF

• spec.clusterDefinitionRef is the name of the cluster definition CRD that defines the cluster components.
• spec.clusterVersionRef is the name of the cluster version CRD that defines the cluster version.
• spec.componentSpecs is the list of components that define the cluster components.
• spec.componentSpecs.componentDefRef 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 apecloud-mysql -o json | jq '.spec.componentDefs[].name'.
• spec.componentSpecs.name is the name of the component.
• spec.componentSpecs.replicas is the number of replicas of the component.
• spec.componentSpecs.resources is the resource requirements of the component.
• spec.componentSpecs.volumeClaimTemplates is the list of volume claim templates that define the volume claim templates for the component.
• spec.terminationPolicy is the policy of cluster termination. The default value is Delete. Valid values are DoNotTerminate, Halt, Delete, WipeOut. DoNotTerminate blocks deletion operation. Halt deletes workload resources such as statefulset and deployment workloads but keep PVCs. Delete is based on Halt and deletes PVCs. WipeOut is based on Delete and wipe out all volume snapshots and snapshot data from a backup storage location.

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

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

Run the following command to see the created MySQL cluster object:

kubectl get cluster mysql-cluster -n demo -o yaml

Output

apiVersion: apps.kubeblocks.io/v1alpha1
kind: Cluster
metadata:
  annotations:
    kubectl.kubernetes.io/last-applied-configuration: |
      {"apiVersion":"apps.kubeblocks.io/v1alpha1","kind":"Cluster","metadata":{"annotations":{},"name":"mysql-cluster","namespace":"demo"},"spec":{"clusterDefinitionRef":"apecloud-mysql","clusterVersionRef":"ac-mysql-8.0.30","componentSpecs":[{"componentDefRef":"mysql","name":"mysql","replicas":1,"resources":{"limits":{"cpu":"0.5","memory":"1Gi"},"requests":{"cpu":"0.5","memory":"1Gi"}},"volumeClaimTemplates":[{"name":"data","spec":{"accessModes":["ReadWriteOnce"],"resources":{"requests":{"storage":"20Gi"}}}}]}],"terminationPolicy":"Delete"}}
  creationTimestamp: "2023-07-17T09:03:23Z"
  finalizers:
  - cluster.kubeblocks.io/finalizer
  generation: 1
  labels:
    clusterdefinition.kubeblocks.io/name: apecloud-mysql
    clusterversion.kubeblocks.io/name: ac-mysql-8.0.30
  name: mysql-cluster
  namespace: demo
  resourceVersion: "27158"
  uid: de7c9fa4-7b94-4227-8852-8d76263aa326
spec:
  clusterDefinitionRef: apecloud-mysql
  clusterVersionRef: ac-mysql-8.0.30
  componentSpecs:
  - componentDefRef: mysql
    monitor: false
    name: mysql
    noCreatePDB: false
    replicas: 1
    resources:
      limits:
        cpu: "0.5"
        memory: 1Gi
      requests:
        cpu: "0.5"
        memory: 1Gi
    volumeClaimTemplates:
    - name: data
      spec:
        accessModes:
        - ReadWriteOnce
        resources:
          requests:
            storage: 20Gi
  terminationPolicy: Delete
status:
  clusterDefGeneration: 2
  components:
    mysql:
      consensusSetStatus:
        leader:
          accessMode: None
          name: ""
          pod: Unknown
      phase: Failed
      podsReady: true
      podsReadyTime: "2023-07-17T09:03:37Z"
  conditions:
  - lastTransitionTime: "2023-07-17T09:03:23Z"
    message: 'The operator has started the provisioning of Cluster: mysql-cluster'
    observedGeneration: 1
    reason: PreCheckSucceed
    status: "True"
    type: ProvisioningStarted
  - lastTransitionTime: "2023-07-17T09:03:23Z"
    message: Successfully applied for resources
    observedGeneration: 1
    reason: ApplyResourcesSucceed
    status: "True"
    type: ApplyResources
  - lastTransitionTime: "2023-07-17T09:03:37Z"
    message: all pods of components are ready, waiting for the probe detection successful
    reason: AllReplicasReady
    status: "True"
    type: ReplicasReady
  - lastTransitionTime: "2023-07-17T09:03:23Z"
    message: 'pods are unavailable in Components: [mysql], refer to related component
      message in Cluster.status.components'
    reason: ComponentsNotReady
    status: "False"
    type: Ready
  observedGeneration: 1
  phase: Running

Connect to a MySQL Cluster

kbcli

kbcli cluster connect <clustername>  --namespace <name>

kubectl

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

KubeBlocks operator creates a new Secret called mysql-cluster-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 -n demo mysql-cluster-conn-credential -o jsonpath='{.data.\username}' | base64 -d
   >
   root
   
   kubectl get secrets -n demo mysql-cluster-conn-credential -o jsonpath='{.data.\password}' | base64 -d
   >
   2gvztbvz

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

   kubectl exec -ti -n demo mysql-cluster-mysql-0 -- bash
   
   mysql -uroot -p2gvztbvz

port-forward

You can also port forward the service to connect to a database from your local machine.

1. Run the following command to port forward the service.

   kubectl port-forward svc/mysql-cluster-mysql 3306:3306 -n demo

2. Open a new terminal and run the following command to connect to the database.

   mysql -uroot -p2gvztbvz

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