Create and connect to an ApeCloud MySQL cluster

This tutorial shows how to create and connect to an ApeCloud 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 by Helm.

• Check whether the ApeCloud MySQL Addon is enabled. The ApeCloud MySQL Addon is enabled by KubeBlocks by default. If you disable it when installing KubeBlocks,enable it first.

  kbcli

  kbcli addon list
  >
  NAME                           VERSION         PROVIDER    STATUS     AUTO-INSTALL
  ...
  apecloud-mysql                 0.9.0           apecloud    Enabled    true
  ...

  kubectl

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

• 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.

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

  View all available versions for creating a cluster.

  kubectl get clusterversions -l clusterdefinition.kubeblocks.io/name=apecloud-mysql
  >
  NAME                CLUSTER-DEFINITION   STATUS      AGE
  ac-mysql-8.0.30     apecloud-mysql       Available   85m

• 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 ApeCloud 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. To ensure high availability, all replicas are distributed on different nodes by default.

kbcli

1. Create an ApeCloud MySQL cluster.

   Below are some common examples to create a cluster with default settings. If you want to customize your cluster specifications, kbcli provides various options, such as setting cluster version, termination policy, CPU, and memory. You can view these options by adding --help or -h flag.

   kbcli cluster create apecloud-mysql --help
   
   kbcli cluster create apecloud-mysql -h

   Create a Standalone.

   kbcli cluster create mycluster --cluster-definition apecloud-mysql --namespace demo

   Create a RaftGroup Cluster.

   kbcli cluster create mycluster --cluster-definition apecloud-mysql --set replicas=3 --namespace demo

   If you only have one node for deploying a RaftGroup Cluster, set the topology-keys as null when creating a RaftGroup Cluster. But you should note that for a production environment, it is not recommended to deploy all replicas on one node, which may decrease the cluster availability.

   kbcli cluster create mycluster --cluster-definition apecloud-mysql --set replicas=3 --topology-keys null --namespace demo

2. Verify whether this cluster is created successfully.

   kbcli cluster list -n demo
   >
   NAME        NAMESPACE   CLUSTER-DEFINITION   VERSION           TERMINATION-POLICY   STATUS    CREATED-TIME
   mycluster   demo        apecloud-mysql       ac-mysql-8.0.30   Delete               Running   Sep 19,2024 16:01 UTC+0800

kubectl

1. Create an ApeCloud MySQL cluster.

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

   If you only have one node for deploying a RaftGroup 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: apecloud-mysql
     clusterVersionRef: ac-mysql-8.0.30
     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
       - general
       - slow
       disableExporter: true
       replicas: 3
       serviceAccountName: kb-acmysql-cluster
       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

   Field	Definition
   spec.clusterDefinitionRef	It specifies the name of the ClusterDefinition for creating a specific type of cluster.
   spec.clusterVersionRef	It is the name of the cluster version CRD that defines the cluster version.
   spec.terminationPolicy	It 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.affinity	It 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.podAntiAffinity	It 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.topologyKeys	It represents the key of node labels used to define the topology domain for Pod anti-affinity and Pod spread constraints.
   spec.tolerations	It is an array that specifies tolerations attached to the cluster's Pods, allowing them to be scheduled onto nodes with matching taints.
   spec.componentSpecs	It is the list of components that define the cluster components. This field allows customized configuration of each component within a cluster.
   spec.componentSpecs.componentDefRef	It 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	It specifies the name of the component.
   spec.componentSpecs.disableExporter	It defines whether the monitoring function is enabled.
   spec.componentSpecs.replicas	It specifies the number of replicas of the component.
   spec.componentSpecs.resources	It specifies the resource requirements of the component.

   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 details of the created ApeCloud MySQL cluster:

   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   apecloud-mysql       ac-mysql-8.0.30   Delete               Running   12m

Connect to an ApeCloud MySQL Cluster

kbcli

kbcli cluster connect mycluster  -n demo

kubectl

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 ApeCloud 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 mycluster-conn-credential -o jsonpath='{.data.username}' | base64 -d
   >
   root
   
   kubectl get secrets -n demo mycluster-conn-credential -o jsonpath='{.data.password}' | base64 -d
   >
   2gvztbvz

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

   kubectl exec -ti -n demo mycluster-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/mycluster-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.