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update major version of MySQL Group Replication

This guide will show you how to use KubeDB enterprise operator to update the major version of MySQL Group Replication.

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.
Install KubeDB community and enterprise operator in your cluster following the steps here.
You should be familiar with the following KubeDB concepts:

To keep everything isolated, we are going to use 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/guides/mysql/update-version/majorversion/group-replication/yamls directory of kubedb/docs repository.

Apply Version updating on Group Replication

Here, we are going to deploy a MySQL group replication using a supported version by KubeDB operator. Then we are going to apply updating on it.

Prepare Group Replication

At first, we are going to deploy a group replication using supported that MySQL version whether it is possible to update from this version to another. In the next two sections, we are going to find out the supported version and version update constraints.

Find supported MySQL Version:

When you have installed KubeDB, it has created MySQLVersion CR for all supported MySQL versions. Let’s check the supported MySQL versions,

$ kubectl get mysqlversion 
NAME            VERSION   DISTRIBUTION   DB_IMAGE                    DEPRECATED   AGE
5.7.35-v1       5.7.35    Official       mysql:5.7.35                             13d
5.7.36          5.7.36    Official       mysql:5.7.36                             13d
8.0.17          8.0.17    Official       mysql:8.0.17                             13d
8.0.27          8.0.27    Official       mysql:8.0.27                             13d
8.0.27-innodb   8.0.27    MySQL          mysql/mysql-server:8.0.27                13d
8.0.29          8.0.29    Official       mysql:8.0.29                             13d
8.0.3-v4        8.0.3     Official       mysql:8.0.3                              13d

The version above that does not show DEPRECATED true is supported by KubeDB for MySQL. You can use any non-deprecated version. Now, we are going to select a non-deprecated version from MySQLVersion for MySQL group replication that will be possible to update from this version to another version. In the next section, we are going to verify version update constraints.

Check update Constraints:

Database version update constraints is a constraint that shows whether it is possible or not possible to update from one version to another. Let’s check the version update constraints of MySQL 5.7.36,

$ kubectl get mysqlversion 5.7.36 -o yaml | kubectl neat
apiVersion: catalog.kubedb.com/v1alpha1
kind: MySQLVersion
metadata:
  annotations:
    meta.helm.sh/release-name: kubedb-catalog
    meta.helm.sh/release-namespace: kubedb
  creationTimestamp: "2022-06-16T13:52:58Z"
  generation: 1
  labels:
    app.kubernetes.io/instance: kubedb-catalog
    app.kubernetes.io/managed-by: Helm
    app.kubernetes.io/name: kubedb-catalog
    app.kubernetes.io/version: v2022.03.28
    helm.sh/chart: kubedb-catalog-v2022.03.28
  name: 5.7.36
  resourceVersion: "1092465"
  uid: 4cc87fc8-efd7-4e69-bb12-4454a2b1bf06
spec:
  coordinator:
    image: kubedb/mysql-coordinator:v0.5.0
  db:
    image: mysql:5.7.36
  distribution: Official
  exporter:
    image: kubedb/mysqld-exporter:v0.13.1
  initContainer:
    image: kubedb/mysql-init:5.7-v2
  podSecurityPolicies:
    databasePolicyName: mysql-db
  replicationModeDetector:
    image: kubedb/replication-mode-detector:v0.13.0
  stash:
    addon:
      backupTask:
        name: mysql-backup-5.7.25
      restoreTask:
        name: mysql-restore-5.7.25
  updateConstraints:
    denylist:
      groupReplication:
      - < 5.7.36
      standalone:
      - < 5.7.36
  version: 5.7.36

The above spec.updateConstraints.denylist of 5.7.36 is showing that updating below version of 5.7.36 is not possible for both group replication and standalone. That means, it is possible to update any version above 5.7.36. Here, we are going to create a MySQL Group Replication using MySQL 5.7.36. Then we are going to update this version to 8.0.29.

Deploy MySQL Group Replication:

In this section, we are going to deploy a MySQL group replication with 3 members. Then, in the next section we will update the version of the members using updating. Below is the YAML of the MySQL cr that we are going to create,

apiVersion: kubedb.com/v1alpha2
kind: MySQL
metadata:
  name: my-group
  namespace: demo
spec:
  version: "5.7.36"
  replicas: 3
  topology:
    mode: GroupReplication
  storageType: Durable
  storage:
    storageClassName: "standard"
    accessModes:
      - ReadWriteOnce
    resources:
      requests:
        storage: 1Gi
  terminationPolicy: WipeOut

Let’s create the MySQL cr we have shown above,

$ kubectl create -f https://github.com/kubedb/docs/raw/v2023.08.18/docs/guides/mysql/update-version/majorversion/group-replication/yamls/group_replication.yaml
mysql.kubedb.com/my-group created

Wait for the cluster to be ready:

KubeDB operator watches for MySQL objects using Kubernetes API. When a MySQL object is created, KubeDB operator will create a new StatefulSet, Services, and Secrets, etc. A secret called my-group-auth (format: {mysql-object-name}-auth) will be created storing the password for mysql superuser. Now, watch MySQL is going to Running state and also watch StatefulSet and its pod is created and going to Running state,

$ watch -n 3 kubectl get my -n demo my-group

NAME       VERSION      STATUS    AGE
my-group   5.7.36    Running   5m52s

$ watch -n 3 kubectl get sts -n demo my-group

NAME       READY   AGE
my-group   3/3     7m12s

$ watch -n 3 kubectl get pod -n demo -l app.kubernetes.io/name=mysqls.kubedb.com,app.kubernetes.io/instance=my-group

NAME         READY   STATUS    RESTARTS   AGE
my-group-0   2/2     Running   0          11m
my-group-1   2/2     Running   0          9m53s
my-group-2   2/2     Running   0          6m48s

Let’s verify the MySQL, the StatefulSet and its Pod image version,

$ kubectl get my -n demo my-group -o=jsonpath='{.spec.version}{"\n"}'
5.7.36

$ kubectl get sts -n demo -l app.kubernetes.io/name=mysqls.kubedb.com,app.kubernetes.io/instance=my-group -o json | jq '.items[].spec.template.spec.containers[1].image'
"kubedb/mysql:5.7.36"

$ kubectl get pod -n demo -l app.kubernetes.io/name=mysqls.kubedb.com,app.kubernetes.io/instance=my-group -o json | jq '.items[].spec.containers[1].image'
"kubedb/mysql:5.7.36"
"kubedb/mysql:5.7.36"
"kubedb/mysql:5.7.36"

Let’s also verify that the StatefulSet’s pods have joined into a group replication,

$ kubectl get secrets -n demo my-group-auth -o jsonpath='{.data.\username}' | base64 -d
root

$ kubectl get secrets -n demo my-group-auth -o jsonpath='{.data.\password}' | base64 -d
7gUARa&Jkg.ypJE8

$ kubectl exec -it -n demo my-group-0 -c mysql -- mysql -u root --password='7gUARa&Jkg.ypJE8' --host=my-group-0.my-group-pods.demo -e "select * from performance_schema.replication_group_members"
mysql: [Warning] Using a password on the command line interface can be insecure.
+---------------------------+--------------------------------------+-----------------------------------+-------------+--------------+
| CHANNEL_NAME              | MEMBER_ID                            | MEMBER_HOST                       | MEMBER_PORT | MEMBER_STATE |
+---------------------------+--------------------------------------+-----------------------------------+-------------+--------------+
| group_replication_applier | b0e71e0c-f849-11ec-a315-46392c50e39c | my-group-1.my-group-pods.demo.svc |        3306 | ONLINE       |
| group_replication_applier | b34b16d7-f849-11ec-9362-a2f432876ee4 | my-group-2.my-group-pods.demo.svc |        3306 | ONLINE       |
| group_replication_applier | b5542a4a-f849-11ec-9a75-3e8abd17fee6 | my-group-0.my-group-pods.demo.svc |        3306 | ONLINE       |
+---------------------------+--------------------------------------+-----------------------------------+-------------+--------------+

We are ready to apply updating on this MySQL group replication.

UpdateVesion

Here, we are going to update the MySQL group replication from 5.7.36 to 8.0.29.

Create MySQLOpsRequest:

To update your database cluster, you have to create a MySQLOpsRequest cr with your desired version that supported by KubeDB. Below is the YAML of the MySQLOpsRequest cr that we are going to create,

apiVersion: ops.kubedb.com/v1alpha1
kind: MySQLOpsRequest
metadata:
  name: my-update-major-group
  namespace: demo
spec:
  type: UpdateVersion
  databaseRef:
    name: my-group
  updateVersion:
    targetVersion: "8.0.29"

Here,

spec.databaseRef.name specifies that we are performing operation on my-group MySQL database.
spec.type specifies that we are going to perform UpdateVersion on our database.
spec.updateVersion.targetVersion specifies expected version 8.0.29 after updating.

Let’s create the MySQLOpsRequest cr we have shown above,

$ kubectl apply -f https://github.com/kubedb/docs/raw/v2023.08.18/docs/guides/mysql/update-version/majorversion/group-replication/yamls/update_major_version_group.yaml
mysqlopsrequest.ops.kubedb.com/my-update-major-group created

Note: During the upgradation of the major version of MySQL group replication, a new StatefulSet is created by the KubeDB enterprise operator and the old one is deleted. The name of the newly created StatefulSet is formed as follows: <mysql-name>-<suffix>. Here, <suffix> is a positive integer number and starts with 1. It’s determined as follows: For one-time major version updating of group replication, the suffix will be 1. For the 2nd time major version updating of group replication, the suffix will be 2. It will be continued…

Verify MySQL version updated successfully:

If everything goes well, KubeDB enterprise operator will create a new StatefulSet named my-group-1 with the desire updated version and delete the old one.

At first, we will wait for MySQLOpsRequest to be successful. Run the following command to watch MySQlOpsRequest cr,

$ watch -n 3 kubectl get myops -n demo my-update-major-group

NAME                    TYPE            STATUS       AGE
my-update-major-group   UpdateVersion   Successful   5m26s

You can see from the above output that the MySQLOpsRequest has succeeded. If we describe the MySQLOpsRequest, we shall see that the MySQL group replication is updated with new images and the StatefulSet is created with a new image.

$ kubectl describe myops -n demo my-update-major-group
Name:         my-update-major-group
Namespace:    demo
Labels:       <none>
Annotations:  <none>
API Version:  ops.kubedb.com/v1alpha1
Kind:         MySQLOpsRequest
Metadata:
  Creation Timestamp:  2022-06-30T07:55:16Z
    Manager:         kubedb-ops-manager
    Operation:       Update
    Time:            2022-06-30T07:55:16Z
  Resource Version:  1708721
  UID:               460319fc-8dc4-45d7-8958-fa84e24d5f51
Spec:
  Database Ref:
    Name:  my-group
  Type:    UpdateVersion
  UpdateVersion:
    Target Version:  8.0.29
Status:
  Conditions:
    Last Transition Time:  2022-06-30T07:55:16Z
    Message:               Controller has started to Progress the MySQLOpsRequest: demo/my-update-major-group
    Observed Generation:   1
    Reason:                OpsRequestProgressingStarted
    Status:                True
    Type:                  Progressing
    Last Transition Time:  2022-06-30T07:55:16Z
    Message:               MySQL version updateFunc stated for MySQLOpsRequest: demo/my-update-major-group
    Observed Generation:   1
    Reason:                DatabaseVersionupdatingStarted
    Status:                True
    Type:                  updating
    Last Transition Time:  2022-06-30T07:59:16Z
    Message:               Image successfully updated in MySQL: demo/my-group for MySQLOpsRequest: my-update-major-group 
    Observed Generation:   1
    Reason:                SuccessfullyUpdatedDatabaseVersion
    Status:                True
    Type:                  UpdateVersion
    Last Transition Time:  2022-06-30T07:59:16Z
    Message:               Controller has successfully updated the MySQL demo/my-update-major-group
    Observed Generation:   1
    Reason:                OpsRequestProcessedSuccessfully
    Status:                True
    Type:                  Successful
  Observed Generation:     3
  Phase:                   Successful
Events:
  Type    Reason      Age    From                        Message
  ----    ------      ----   ----                        -------
  Normal  Starting    5m24s  KubeDB Enterprise Operator  Start processing for MySQLOpsRequest: demo/my-update-major-group
  Normal  Starting    5m24s  KubeDB Enterprise Operator  Pausing MySQL databse: demo/my-group
  Normal  Successful  5m24s  KubeDB Enterprise Operator  Successfully paused MySQL database: demo/my-group for MySQLOpsRequest: my-update-major-group
  Normal  Starting    5m24s  KubeDB Enterprise Operator  Updating MySQL images: demo/my-group for MySQLOpsRequest: my-update-major-group
  Normal  Starting    5m19s  KubeDB Enterprise Operator  Restarting Pod: my-group-1/demo
  Normal  Starting    3m59s  KubeDB Enterprise Operator  Restarting Pod: my-group-2/demo
  Normal  Starting    2m39s  KubeDB Enterprise Operator  Restarting Pod: my-group-0/demo
  Normal  Successful  84s    KubeDB Enterprise Operator  Image successfully updated in MySQL: demo/my-group for MySQLOpsRequest: my-update-major-group
  Normal  Starting    84s    KubeDB Enterprise Operator  Resuming MySQL database: demo/my-group
  Normal  Successful  84s    KubeDB Enterprise Operator  Successfully resumed MySQL database: demo/my-group
  Normal  Successful  84s    KubeDB Enterprise Operator  Controller has Successfully updated the version of MySQL : demo/my-group

Now, we are going to verify whether the MySQL and StatefulSet and it’s Pod have updated with new image. Let’s check,

$ kubectl get my -n demo my-group -o=jsonpath='{.spec.version}{"\n"}'
8.0.27

$ kubectl get sts -n demo -l app.kubernetes.io/name=mysqls.kubedb.com,app.kubernetes.io/instance=my-group -o json | jq '.items[].spec.template.spec.containers[1].image'
"kubedb/mysql:8.0.29"

$ kubectl get pod -n demo -l app.kubernetes.io/name=mysqls.kubedb.com,app.kubernetes.io/instance=my-group -o json | jq '.items[].spec.containers[1].image'
"kubedb/mysql:8.0.29"
"kubedb/mysql:8.0.29"
"kubedb/mysql:8.0.29"

Let’s also check the StatefulSet pods have joined the MySQL group replication,

$ kubectl get secrets -n demo my-group-auth -o jsonpath='{.data.\username}' | base64 -d
root

$ kubectl get secrets -n demo my-group-auth -o jsonpath='{.data.\password}' | base64 -d
7gUARa&Jkg.ypJE8

$ kubectl exec -it -n demo my-group-0 -c mysql -- mysql -u root --password='7gUARa&Jkg.ypJE8' --host=my-group-0.my-group-pods.demo -e "select * from performance_schema.replication_group_members"
mysql: [Warning] Using a password on the command line interface can be insecure.
+---------------------------+--------------------------------------+-----------------------------------+-------------+--------------+-------------+----------------+----------------------------+
| CHANNEL_NAME              | MEMBER_ID                            | MEMBER_HOST                       | MEMBER_PORT | MEMBER_STATE | MEMBER_ROLE | MEMBER_VERSION | MEMBER_COMMUNICATION_STACK |
+---------------------------+--------------------------------------+-----------------------------------+-------------+--------------+-------------+----------------+----------------------------+
| group_replication_applier | b0e71e0c-f849-11ec-a315-46392c50e39c | my-group-1.my-group-pods.demo.svc |        3306 | ONLINE       | PRIMARY     | 8.0.29         | XCom                       |
| group_replication_applier | b34b16d7-f849-11ec-9362-a2f432876ee4 | my-group-2.my-group-pods.demo.svc |        3306 | ONLINE       | SECONDARY   | 8.0.29         | XCom                       |
| group_replication_applier | b5542a4a-f849-11ec-9a75-3e8abd17fee6 | my-group-0.my-group-pods.demo.svc |        3306 | ONLINE       | SECONDARY   | 8.0.29         | XCom                       |
+---------------------------+--------------------------------------+-----------------------------------+-------------+--------------+-------------+----------------+----------------------------+

You can see above that our MySQL group replication now has updated members. It verifies that we have successfully updated our cluster.

Cleaning Up

To clean up the Kubernetes resources created by this tutorial, run:

kubectl delete my -n demo my-group
kubectl delete myops -n demo my-update-major-group

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