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KubeDB - MySQL Innodb Cluster
This tutorial will show you how to use KubeDB to provision a MySQL Innodb cluster single-primary mode.
Before You Begin
Before proceeding:
Innodb cluster itself use mysql group replication under the hood
Read mysql group replication concept to learn about MySQL Group Replication.
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.
Now, install KubeDB cli on your workstation and KubeDB operator in your cluster following the steps here.
To keep things isolated, this tutorial uses a separate namespace called
demothroughout this tutorial. Run the following command to prepare your cluster for this tutorial:$ kubectl create ns demo namespace/demo created
Deploy MySQL Innodb Cluster
To deploy a MySQL Innodb cluster, specify spec.topology field in MySQL CRD.
The following is an example MySQL object which creates a MySQL Innodb cluster with three members (one is primary member and the two others are secondary members).
apiVersion: kubedb.com/v1alpha2
kind: MySQL
metadata:
name: innodb
namespace: demo
spec:
version: "8.0.31-innodb"
replicas: 3
topology:
mode: InnoDBCluster
innoDBCluster:
router:
replicas: 1
storageType: Durable
storage:
storageClassName: "standard"
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 1Gi
terminationPolicy: WipeOut
$ kubectl create -f https://github.com/kubedb/docs/raw/v2023.01.17/docs/guides/mysql/clustering/innodb-cluster/yamls/innodb.yaml
mysql.kubedb.com/innodb created
Here,
spec.topologytells about the clustering configuration for MySQL.spec.topology.modespecifies the mode for MySQL cluster. Here we have usedInnoDBClusterto tell the operator that we want to deploy a MySQL Innodb Cluster.spec.topology.innoDBClustercontains the InnodbCluster info.Innodb cluster comes with a router as a load balancerspec.topology.Router.replicais for the number of replica fo innodb cluster router.spec.storagespecifies the StorageClass of PVC dynamically allocated to store data for this database. This storage spec will be passed to the StatefulSet created by KubeDB operator to run database pods. So, each members will have a pod of this storage configuration. You can specify any StorageClass available in your cluster with appropriate resource requests.
KubeDB operator watches for MySQL objects using Kubernetes API. When a MySQL object is created, KubeDB operator will create a new StatefulSet and a Service with the matching MySQL object name. KubeDB operator will also create a governing service for the StatefulSet with the name <mysql-object-name>-pods.
$ kubectl dba describe my -n demo innodb
Name: innodb
Namespace: demo
CreationTimestamp: Tue, 15 Nov 2022 15:14:42 +0600
Labels: <none>
Annotations: kubectl.kubernetes.io/last-applied-configuration={"apiVersion":"kubedb.com/v1alpha2","kind":"MySQL","metadata":{"annotations":{},"name":"innodb","namespace":"demo"},"spec":{"replicas":3,"storage":{"ac...
Replicas: 3 total
Status: Provisioning
StorageType: Durable
Volume:
StorageClass: standard
Capacity: 1Gi
Access Modes: RWO
Paused: false
Halted: false
Termination Policy: WipeOut
StatefulSet:
Name: innodb
CreationTimestamp: Tue, 15 Nov 2022 15:14:42 +0600
Labels: app.kubernetes.io/component=database
app.kubernetes.io/instance=innodb
app.kubernetes.io/managed-by=kubedb.com
app.kubernetes.io/name=mysqls.kubedb.com
mysql.kubedb.com/component=database
Annotations: <none>
Replicas: 824641134776 desired | 1 total
Pods Status: 0 Running / 1 Waiting / 0 Succeeded / 0 Failed
Service:
Name: innodb
Labels: app.kubernetes.io/component=database
app.kubernetes.io/instance=innodb
app.kubernetes.io/managed-by=kubedb.com
app.kubernetes.io/name=mysqls.kubedb.com
mysql.kubedb.com/component=database
Annotations: <none>
Type: ClusterIP
IP: 10.96.244.213
Port: primary 3306/TCP
TargetPort: rw/TCP
Endpoints:
Service:
Name: innodb-pods
Labels: app.kubernetes.io/component=database
app.kubernetes.io/instance=innodb
app.kubernetes.io/managed-by=kubedb.com
app.kubernetes.io/name=mysqls.kubedb.com
mysql.kubedb.com/component=database
Annotations: <none>
Type: ClusterIP
IP: None
Port: db 3306/TCP
TargetPort: db/TCP
Endpoints: 10.244.0.26:3306
Service:
Name: innodb-standby
Labels: app.kubernetes.io/component=database
app.kubernetes.io/instance=innodb
app.kubernetes.io/managed-by=kubedb.com
app.kubernetes.io/name=mysqls.kubedb.com
mysql.kubedb.com/component=database
Annotations: <none>
Type: ClusterIP
IP: 10.96.146.147
Port: standby 3306/TCP
TargetPort: ro/TCP
Endpoints:
Auth Secret:
Name: innodb-auth
Labels: app.kubernetes.io/component=database
app.kubernetes.io/instance=innodb
app.kubernetes.io/managed-by=kubedb.com
app.kubernetes.io/name=mysqls.kubedb.com
mysql.kubedb.com/component=database
Annotations: <none>
Type: kubernetes.io/basic-auth
Data:
password: 16 bytes
username: 4 bytes
AppBinding:
Metadata:
Annotations:
kubectl.kubernetes.io/last-applied-configuration: {"apiVersion":"kubedb.com/v1alpha2","kind":"MySQL","metadata":{"annotations":{},"name":"innodb","namespace":"demo"},"spec":{"replicas":3,"storage":{"accessModes":["ReadWriteOnce"],"resources":{"requests":{"storage":"1Gi"}},"storageClassName":"standard"},"storageType":"Durable","terminationPolicy":"WipeOut","topology":{"innoDBCluster":{"router":{"replicas":1}},"mode":"InnoDBCluster"},"version":"8.0.31-innodb"}}
Creation Timestamp: 2022-11-15T09:14:42Z
Labels:
app.kubernetes.io/component: database
app.kubernetes.io/instance: innodb
app.kubernetes.io/managed-by: kubedb.com
app.kubernetes.io/name: mysqls.kubedb.com
mysql.kubedb.com/component: database
Name: innodb
Namespace: demo
Spec:
Client Config:
Service:
Name: innodb
Path: /
Port: 3306
Scheme: mysql
URL: tcp(innodb.demo.svc:3306)/
Parameters:
API Version: appcatalog.appscode.com/v1alpha1
Kind: StashAddon
Stash:
Addon:
Backup Task:
Name: mysql-backup-8.0.21
Params:
Name: args
Value: --all-databases --set-gtid-purged=OFF
Restore Task:
Name: mysql-restore-8.0.21
Secret:
Name: innodb-auth
Type: kubedb.com/mysql
Version: 8.0.31
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal Phase Changed 27s MySQL operator phase changed from to Provisioning reason:
Normal Successful 27s MySQL operator Successfully created governing service
Normal Successful 27s MySQL operator Successfully created service for primary/standalone
Normal Successful 27s MySQL operator Successfully created service for secondary replicas
Normal Successful 27s MySQL operator Successfully created database auth secret
Normal Successful 27s MySQL operator Successfully created StatefulSet
Normal Successful 27s MySQL operator successfully patched created StatefulSet innodb-router
Normal Successful 27s MySQL operator Successfully created MySQL
Normal Successful 27s MySQL operator Successfully created appbinding
$ kubectl get statefulset -n demo
NAME READY AGE
NAME READY AGE
innodb 3/3 2m17s
innodb-router 1/1 2m17s
$ kubectl get pvc -n demo
NAME STATUS VOLUME CAPACITY ACCESS MODES STORAGECLASS AGE
data-innodb-0 Bound pvc-6f7f8ebd-0b56-45fb-b91a-fe133bfae594 1Gi RWO standard 2m47s
data-innodb-1 Bound pvc-16f9d6df-ce46-49da-9720-415d7f7d8b69 1Gi RWO standard 113s
data-innodb-2 Bound pvc-8cfcb761-eb63-4a12-bc7e-5d86f727330e 1Gi RWO standard 88s
$ kubectl get pv -n demo
NAME CAPACITY ACCESS MODES RECLAIM POLICY STATUS CLAIM STORAGECLASS REASON AGE
pvc-6f7f8ebd-0b56-45fb-b91a-fe133bfae594 1Gi RWO Delete Bound demo/data-innodb-0 standard 3m50s
pvc-16f9d6df-ce46-49da-9720-415d7f7d8b69 1Gi RWO Delete Bound demo/data-innodb-1 standard 2m38s
pvc-8cfcb761-eb63-4a12-bc7e-5d86f727330e 1Gi RWO Delete Bound demo/data-innodb-2 standard 2m32s
$ kubectl get service -n demo
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
innodb ClusterIP 10.96.244.213 <none> 3306/TCP 5m23s
innodb-pods ClusterIP None <none> 3306/TCP 5m23s
innodb-standby ClusterIP 10.96.146.147 <none> 3306/TCP 5m23s
KubeDB operator sets the status.phase to Running once the database is successfully created. Run the following command to see the modified MySQL object:
$ kubectl get my -n demo innodb -o yaml | kubectl neat
apiVersion: kubedb.com/v1alpha2
kind: MySQL
metadata:
name: innodb
namespace: demo
spec:
authSecret:
name: innodb-auth
podTemplate:
spec:
affinity:
podAntiAffinity:
preferredDuringSchedulingIgnoredDuringExecution:
- podAffinityTerm:
labelSelector:
matchLabels:
app.kubernetes.io/instance: innodb
app.kubernetes.io/managed-by: kubedb.com
app.kubernetes.io/name: mysqls.kubedb.com
namespaces:
- demo
topologyKey: kubernetes.io/hostname
weight: 100
- podAffinityTerm:
labelSelector:
matchLabels:
app.kubernetes.io/instance: innodb
app.kubernetes.io/managed-by: kubedb.com
app.kubernetes.io/name: mysqls.kubedb.com
namespaces:
- demo
topologyKey: failure-domain.beta.kubernetes.io/zone
weight: 50
resources:
limits:
cpu: 500m
memory: 1Gi
requests:
cpu: 500m
memory: 1Gi
serviceAccountName: innodb
replicas: 3
storage:
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 1Gi
storageClassName: standard
storageType: Durable
terminationPolicy: WipeOut
topology:
innoDBCluster:
mode: Single-Primary
router:
replicas: 1
mode: InnoDBCluster
version: 8.0.31-innodb
status:
observedGeneration: 2
phase: Running
Connect with MySQL database
KubeDB operator has created a new Secret called innodb-auth (format: {mysql-object-name}-auth) for storing the password for mysql superuser. This secret contains a username key which contains the username for MySQL superuser and a password key which contains the password for MySQL superuser.
If you want to use an existing secret please specify that when creating the MySQL object using spec.authSecret.name. While creating this secret manually, make sure the secret contains these two keys containing data username and password and also make sure of using root as value of username. For more details see here.
Now, you can connect to this database from your terminal using the mysql user and password.
$ kubectl get secrets -n demo innodb-auth -o jsonpath='{.data.\username}' | base64 -d
root
$ kubectl get secrets -n demo innodb-auth -o jsonpath='{.data.\password}' | base64 -d
ny5jSirIzVtWDcZ7
The operator creates a cluster according to the newly created MySQL object. This group has 3 members (one primary and two secondary).
You can connect to any of these cluster members. In that case you just need to specify the host name of that member Pod (either PodIP or the fully-qualified-domain-name for that Pod using the governing service named <mysql-object-name>-pods) by --host flag.
# first list the mysql pods list
$ kubectl get pods -n demo -l app.kubernetes.io/instance=innodb
NAME READY STATUS RESTARTS AGE
innodb-0 2/2 Running 0 15m
innodb-1 2/2 Running 0 14m
innodb-2 2/2 Running 0 14m
innodb-router-0 1/1 Running 0 15m
# get the governing service
$ kubectl get service innodb-pods -n demo
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
innodb-pods ClusterIP None <none> 3306/TCP 16m
# list the pods with PodIP
$ kubectl get pods -n demo -l app.kubernetes.io/instance=innodb -o jsonpath='{range.items[*]}{.metadata.name} ........... {.status.podIP} ............ {.metadata.name}.innodb-pods.{.metadata.namespace}{"\\n"}{end}'
innodb-0 ........... 10.244.0.26 ............ innodb-0.innodb-pods.demo
innodb-1 ........... 10.244.0.28 ............ innodb-1.innodb-pods.demo
innodb-2 ........... 10.244.0.30 ............ innodb-2.innodb-pods.demo
Now you can connect to this database using the above info. Ignore the warning message. It is happening for using password in the command.
# connect to the 1st server
$ kubectl exec -it -n demo innodb-0 -c mysql -- mysql -u root --password='ny5jSirIzVtWDcZ7' --host=innodb-0.innodb-pods.demo -e "select 1;"
mysql: [Warning] Using a password on the command line interface can be insecure.
+---+
| 1 |
+---+
| 1 |
+---+
# connect to the 2nd server
$ kubectl exec -it -n demo innodb-0 -c mysql -- mysql -u root --password='ny5jSirIzVtWDcZ7' --host=innodb-1.innodb-pods.demo -e "select 1;"
mysql: [Warning] Using a password on the command line interface can be insecure.
+---+
| 1 |
+---+
| 1 |
+---+
# connect to the 3rd server
$ kubectl exec -it -n demo innodb-0 -c mysql -- mysql -u root --password='ny5jSirIzVtWDcZ7' --host=innodb-2.innodb-pods.demo -e "select 1;"
mysql: [Warning] Using a password on the command line interface can be insecure.
+---+
| 1 |
+---+
| 1 |
+---+
Check the Innodb Cluster status
The main advantage of innodb cluster is its comes with an admin shell from where you are able to call the mysql admin api and configure cluster and it provide some functionality wokring with the cluster. Let’s exec into one of the pod to see the cluster status.
$ kubectl exec -it -n demo innodb-0 -c mysql -- mysqlsh -u root --password='ny5jSirIzVtWDcZ7' --host=innodb-0.innodb-pods.demo
MySQL innodb-0.innodb-pods.demo:33060+ ssl JS > dba.getCluster().status()
{
"clusterName": "innodb",
"defaultReplicaSet": {
"name": "default",
"primary": "innodb-0.innodb-pods.demo.svc:3306",
"ssl": "REQUIRED",
"status": "OK",
"statusText": "Cluster is ONLINE and can tolerate up to ONE failure.",
"topology": {
"innodb-0.innodb-pods.demo.svc:3306": {
"address": "innodb-0.innodb-pods.demo.svc:3306",
"memberRole": "PRIMARY",
"mode": "R/W",
"readReplicas": {},
"replicationLag": "applier_queue_applied",
"role": "HA",
"status": "ONLINE",
"version": "8.0.31"
},
"innodb-1.innodb-pods.demo.svc:3306": {
"address": "innodb-1.innodb-pods.demo.svc:3306",
"memberRole": "SECONDARY",
"mode": "R/O",
"readReplicas": {},
"replicationLag": "applier_queue_applied",
"role": "HA",
"status": "ONLINE",
"version": "8.0.31"
},
"innodb-2.innodb-pods.demo.svc:3306": {
"address": "innodb-2.innodb-pods.demo.svc:3306",
"memberRole": "SECONDARY",
"mode": "R/O",
"readReplicas": {},
"replicationLag": "applier_queue_applied",
"role": "HA",
"status": "ONLINE",
"version": "8.0.31"
}
},
"topologyMode": "Single-Primary"
},
"groupInformationSourceMember": "innodb-0.innodb-pods.demo.svc:3306"
}
Data Availability
In a MySQL Cluster, only the primary member can write not the secondary. But you can read data from any member. In this tutorial, we will insert data from primary, and we will see whether we can get the data from any other member.
Read the comment written for the following commands. They contain the instructions and explanations of the commands.
# create a database on primary
$ kubectl exec -it -n demo innodb-0 -- mysql -u root --password='ny5jSirIzVtWDcZ7' --host=innodb-0.innodb-pods.demo -e "CREATE DATABASE playground;"
mysql: [Warning] Using a password on the command line interface can be insecure.
# create a table
$ kubectl exec -it -n demo innodb-0 -- mysql -u root --password='ny5jSirIzVtWDcZ7' --host=innodb-0.innodb-pods.demo -e "CREATE TABLE playground.equipment ( id INT NOT NULL AUTO_INCREMENT, type VARCHAR(50), quant INT, color VARCHAR(25), PRIMARY KEY(id));"
mysql: [Warning] Using a password on the command line interface can be insecure.
# insert a row
$ kubectl exec -it -n demo innodb-0 -c mysql -- mysql -u root --password='ny5jSirIzVtWDcZ7' --host=innodb-0.innodb-pods.demo -e "INSERT INTO playground.equipment (type, quant, color) VALUES ('slide', 2, 'blue');"
mysql: [Warning] Using a password on the command line interface can be insecure.
# read from primary
$ kubectl exec -it -n demo innodb-0 -c mysql -- mysql -u root --password='ny5jSirIzVtWDcZ7' --host=innodb-0.innodb-pods.demo -e "SELECT * FROM playground.equipment;"
mysql: [Warning] Using a password on the command line interface can be insecure.
+----+-------+-------+-------+
| id | type | quant | color |
+----+-------+-------+-------+
| 1 | slide | 2 | blue |
+----+-------+-------+-------+
In the previous step we have inserted into the primary pod. In the next step we will read from secondary pods to determine whether the data has been successfully copied to the secondary pods.
# read from secondary-1
$ kubectl exec -it -n demo innodb-0 -c mysql -- mysql -u root --password='ny5jSirIzVtWDcZ7' --host=innodb-1.innodb-pods.demo -e "SELECT * FROM playground.equipment;"
mysql: [Warning] Using a password on the command line interface can be insecure.
+----+-------+-------+-------+
| id | type | quant | color |
+----+-------+-------+-------+
| 1 | slide | 2 | blue |
+----+-------+-------+-------+
# read from secondary-2
$ kubectl exec -it -n demo innodb-0 -c mysql -- mysql -u root --password='ny5jSirIzVtWDcZ7' --host=innodb-2.innodb-pods.demo -e "SELECT * FROM playground.equipment;"
mysql: [Warning] Using a password on the command line interface can be insecure.
+----+-------+-------+-------+
| id | type | quant | color |
+----+-------+-------+-------+
| 1 | slide | 2 | blue |
+----+-------+-------+-------+
Write on Secondary Should Fail
Only, primary member preserves the write permission. No secondary can write data.
# try to write on secondary-1
$ kubectl exec -it -n demo innodb-0 -c mysql -- mysql -u root --password='ny5jSirIzVtWDcZ7' --host=innodb-1.innodb-pods.demo -e "INSERT INTO playground.equipment (type, quant, color) VALUES ('mango', 5, 'yellow');"
mysql: [Warning] Using a password on the command line interface can be insecure.
ERROR 1290 (HY000) at line 1: The MySQL server is running with the --super-read-only option so it cannot execute this statement
command terminated with exit code 1
# try to write on secondary-2
$ kubectl exec -it -n demo innodb-0 -c mysql -- mysql -u root --password='ny5jSirIzVtWDcZ7' --host=innodb-2.innodb-pods.demo -e "INSERT INTO playground.equipment (type, quant, color) VALUES ('mango', 5, 'yellow');"
mysql: [Warning] Using a password on the command line interface can be insecure.
ERROR 1290 (HY000) at line 1: The MySQL server is running with the --super-read-only option so it cannot execute this statement
command terminated with exit code 1
Automatic Failover
To test automatic failover, we will force the primary Pod to restart. Since the primary member (Pod) becomes unavailable, the rest of the members will elect a new primary for the cluster. When the old primary comes back, it will join the cluster as a secondary member.
Read the comment written for the following commands. They contain the instructions and explanations of the commands.
# delete the primary Pod innodb-0
$ kubectl delete pod innodb-0 -n demo
pod "innodb-0" deleted
# check the new primary ID
$ kubectl exec -it -n demo innodb-0 -c mysql -- mysql -u root --password='ny5jSirIzVtWDcZ7' --host=innodb-0.innodb-pods.demo -e "show status like '%primary%'"
mysql: [Warning] Using a password on the command line interface can be insecure.
+----------------------------------+--------------------------------------+
| Variable_name | Value |
+----------------------------------+--------------------------------------+
| group_replication_primary_member | 2b77185f-64c6-11ed-9621-e21f33a1cdb1|
+----------------------------------+--------------------------------------+
# now check the cluster status for underlying group replication
$ kubectl exec -it -n demo innodb-0 -c mysql -- mysql -u root --password='ny5jSirIzVtWDcZ7' --host=innodb-0.innodb-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 | 294f333c-64c6-11ed-9893-468480005d43 | innodb-0.innodb-pods.demo.svc | 3306 | ONLINE | SECONDARY | 8.0.31 | MySQL |
| group_replication_applier | 2b77185f-64c6-11ed-9621-e21f33a1cdb1 | innodb-1.innodb-pods.demo.svc | 3306 | ONLINE | PRIMARY | 8.0.31 | MySQL |
| group_replication_applier | 2f0da15c-64c6-11ed-951a-fa8d12ce91a2 | innodb-2.innodb-pods.demo.svc | 3306 | ONLINE | SECONDARY | 8.0.31 | MySQL |
+---------------------------+--------------------------------------+-------------------------------+-------------+--------------+-------------+----------------+----------------------------+
# read data from new primary innodb-1.innodb-pods.demo
$ kubectl exec -it -n demo innodb-1 -c mysql -- mysql -u root --password='ny5jSirIzVtWDcZ7' --host=innodb-1.innodb-pods.demo -e "SELECT * FROM playground.equipment;"
mysql: [Warning] Using a password on the command line interface can be insecure.
+----+-------+-------+-------+
| id | type | quant | color |
+----+-------+-------+-------+
| 1 | slide | 2 | blue |
+----+-------+-------+-------+
Now Let’s read the data from secondary pods to see if the data is consistent.
# read data from secondary-1 innodb-0.innodb-pods.demo
$ kubectl exec -it -n demo innodb-0 -c mysql -- mysql -u root --password='ny5jSirIzVtWDcZ7' --host=innodb-0.innodb-pods.demo -e "SELECT * FROM playground.equipment;"
mysql: [Warning] Using a password on the command line interface can be insecure.
+----+-------+-------+-------+
| id | type | quant | color |
+----+-------+-------+-------+
| 1 | slide | 2 | blue |
+----+-------+-------+-------+
# read data from secondary-2 innodb-2.innodb-pods.demo
$ kubectl exec -it -n demo innodb-0 -c mysql -- mysql -u root --password='ny5jSirIzVtWDcZ7' --host=innodb-2.innodb-pods.demo -e "SELECT * FROM playground.equipment;"
mysql: [Warning] Using a password on the command line interface can be insecure.
+----+-------+-------+-------+
| id | type | quant | color |
+----+-------+-------+-------+
| 7 | slide | 2 | blue |
+----+-------+-------+-------+
Cleaning up
Clean what you created in this tutorial.
kubectl delete -n demo my/innodb
kubectl delete ns demo
Next Steps
- Detail concepts of MySQL object.
- Detail concepts of MySQLDBVersion object.
- Want to hack on KubeDB? Check our contribution guidelines.