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KubeDB - MySQL Semi-sync cluster
This tutorial will show you how to use KubeDB to provision a MySQL semi-synchronous cluster.
Before You Begin
Before proceeding:
Read mysql semi synchronous concept to learn about MySQL Semi sync cluster.
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
Note: The yaml files used in this tutorial are stored in docs/guides/mysql/clustering/semi-sync/yamls folder in GitHub repository kubedb/docs.
Deploy MySQL Semi-sync Cluster
To deploy a single primary MySQL semi-synchronous cluster , specify spec.topology field in MySQL CRD.
The following is an example MySQL object which creates a semi-synchronous cluster with three members (one is primary member and the two others are secondary members).
apiVersion: kubedb.com/v1
kind: MySQL
metadata:
name: semi-sync-mysql
namespace: demo
spec:
version: "8.0.35"
replicas: 3
topology:
mode: SemiSync
semiSync:
sourceWaitForReplicaCount: 1
sourceTimeout: 23h
errantTransactionRecoveryPolicy: PseudoTransaction
storageType: Durable
storage:
storageClassName: "standard"
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 1Gi
deletionPolicy: WipeOut
$ kubectl create -f https://github.com/kubedb/docs/raw/v2024.8.21/docs/guides/mysql/clustering/semi-sync/yamls/semi-sync.yaml
mysql.kubedb.com/semi-sync-mysql created
Here,
spec.topologytells about the clustering configuration for MySQL.spec.topology.modespecifies the mode for MySQL cluster. Here we have usedSemiSyncto tell the operator that we want to deploy a MySQL Semi-synchronous cluster.spec.topology.semiSynccontains semi-synchronous cluster info.spec.topology.semiSync.sourceWaitForReplicaCount:explains the number of replica semi-sync primary wait before commit a transactionspec.topology.semiSync.sourceTimeout:explains the timeout for primary to wait for a replica and fall back to asynchronous replicationspec.topology.semiSync.errantTransactionRecoveryPolicy:it’s possible to have errant transaction during a Primary failover . kubedb supports two types of recovery usingPseudoTransactionandClonespec.storagespecifies the StorageClass of PVC dynamically allocated to store data for this database. This storage spec will be passed to the PetSet 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 PetSet and a Service with the matching MySQL object name. KubeDB operator will also create a governing service for the PetSet with the name <mysql-object-name>-pods.
$ kubectl dba describe my -n demo semi-sync-mysql
Name: semi-sync-mysql
Namespace: demo
CreationTimestamp: Wed, 16 Nov 2022 11:45:53 +0600
Labels: <none>
Annotations: kubectl.kubernetes.io/last-applied-configuration={"apiVersion":"kubedb.com/v1","kind":"MySQL","metadata":{"annotations":{},"name":"semi-sync-mysql","namespace":"demo"},"spec":{"replicas":3,"stor...
Replicas: 3 total
Status: Ready
StorageType: Durable
Volume:
StorageClass: standard
Capacity: 1Gi
Access Modes: RWO
Paused: false
Halted: false
Termination Policy: WipeOut
PetSet:
Name: semi-sync-mysql
CreationTimestamp: Wed, 16 Nov 2022 11:45:53 +0600
Labels: app.kubernetes.io/component=database
app.kubernetes.io/instance=semi-sync-mysql
app.kubernetes.io/managed-by=kubedb.com
app.kubernetes.io/name=mysqls.kubedb.com
Annotations: <none>
Replicas: 824640444456 desired | 3 total
Pods Status: 3 Running / 0 Waiting / 0 Succeeded / 0 Failed
Service:
Name: semi-sync-mysql
Labels: app.kubernetes.io/component=database
app.kubernetes.io/instance=semi-sync-mysql
app.kubernetes.io/managed-by=kubedb.com
app.kubernetes.io/name=mysqls.kubedb.com
Annotations: <none>
Type: ClusterIP
IP: 10.96.121.252
Port: primary 3306/TCP
TargetPort: db/TCP
Endpoints: 10.244.0.18:3306
Service:
Name: semi-sync-mysql-pods
Labels: app.kubernetes.io/component=database
app.kubernetes.io/instance=semi-sync-mysql
app.kubernetes.io/managed-by=kubedb.com
app.kubernetes.io/name=mysqls.kubedb.com
Annotations: <none>
Type: ClusterIP
IP: None
Port: db 3306/TCP
TargetPort: db/TCP
Endpoints: 10.244.0.18:3306,10.244.0.20:3306,10.244.0.22:3306
Port: coordinator 2380/TCP
TargetPort: coordinator/TCP
Endpoints: 10.244.0.18:2380,10.244.0.20:2380,10.244.0.22:2380
Port: coordinatclient 2379/TCP
TargetPort: coordinatclient/TCP
Endpoints: 10.244.0.18:2379,10.244.0.20:2379,10.244.0.22:2379
Service:
Name: semi-sync-mysql-standby
Labels: app.kubernetes.io/component=database
app.kubernetes.io/instance=semi-sync-mysql
app.kubernetes.io/managed-by=kubedb.com
app.kubernetes.io/name=mysqls.kubedb.com
Annotations: <none>
Type: ClusterIP
IP: 10.96.133.61
Port: standby 3306/TCP
TargetPort: db/TCP
Endpoints: 10.244.0.20:3306,10.244.0.22:3306
Auth Secret:
Name: semi-sync-mysql-auth
Labels: app.kubernetes.io/component=database
app.kubernetes.io/instance=semi-sync-mysql
app.kubernetes.io/managed-by=kubedb.com
app.kubernetes.io/name=mysqls.kubedb.com
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/v1","kind":"MySQL","metadata":{"annotations":{},"name":"semi-sync-mysql","namespace":"demo"},"spec":{"replicas":3,"storage":{"accessModes":["ReadWriteOnce"],"resources":{"requests":{"storage":"1Gi"}},"storageClassName":"standard"},"storageType":"Durable","deletionPolicy":"WipeOut","topology":{"mode":"SemiSync","semiSync":{"errantTransactionRecoveryPolicy":"PseudoTransaction","sourceTimeout":"23h","sourceWaitForReplicaCount":1}},"version":"8.0.35"}}
Creation Timestamp: 2022-11-16T05:45:53Z
Labels:
app.kubernetes.io/component: database
app.kubernetes.io/instance: semi-sync-mysql
app.kubernetes.io/managed-by: kubedb.com
app.kubernetes.io/name: mysqls.kubedb.com
Name: semi-sync-mysql
Namespace: demo
Spec:
Client Config:
Service:
Name: semi-sync-mysql
Path: /
Port: 3306
Scheme: mysql
URL: tcp(semi-sync-mysql.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: semi-sync-mysql-auth
Type: kubedb.com/mysql
Version: 8.0.35
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal Phase Changed 7m MySQL operator phase changed from to Provisioning reason:
Normal Successful 7m MySQL operator Successfully created governing service
Normal Successful 7m MySQL operator Successfully created service for primary/standalone
Normal Successful 7m MySQL operator Successfully created service for secondary replicas
Normal Successful 7m MySQL operator Successfully created database auth secret
Normal Successful 7m MySQL operator Successfully created PetSet
Normal Successful 7m MySQL operator Successfully created MySQL
Normal Successful 7m MySQL operator Successfully created appbinding
Normal Successful 7m MySQL operator Successfully patched governing service
Normal Successful 6m MySQL operator Successfully patched governing service
Normal Successful 6m MySQL operator Successfully patched governing service
Normal Successful 6m MySQL operator Successfully patched governing service
Normal Successful 6m MySQL operator Successfully patched governing service
Normal Successful 5m MySQL operator Successfully patched governing service
Normal Successful 5m MySQL operator Successfully patched governing service
Normal Successful 5m MySQL operator Successfully patched governing service
Normal Successful 5m MySQL operator Successfully patched governing service
Normal Phase Changed 5m MySQL operator phase changed from Provisioning to Ready reason:
Normal Successful 5m MySQL operator Successfully patched governing service
g
$ kubectl get petset -n demo
NAME READY AGE
semi-sync-mysql 3/3 3m47s
$ kubectl get pvc -n demo
NAME STATUS VOLUME CAPACITY ACCESS MODES STORAGECLASS AGE
data-semi-sync-mysql-0 Bound pvc-4f8538f6-a6ce-4233-b533-8566852f5b98 1Gi RWO standard 4m16s
data-semi-sync-mysql-1 Bound pvc-8823d3ad-d614-4172-89ac-c2284a17f502 1Gi RWO standard 4m11s
data-semi-sync-mysql-2 Bound pvc-94f1c312-50e3-41e1-94a8-a820be0abc08 1Gi RWO standard 4m7s
s
$ kubectl get pv -n demo
NAME CAPACITY ACCESS MODES RECLAIM POLICY STATUS CLAIM STORAGECLASS REASON AGE
pvc-4f8538f6-a6ce-4233-b533-8566852f5b98 1Gi RWO Delete Bound demo/data-semi-sync-mysql-0 standard 4m39s
pvc-8823d3ad-d614-4172-89ac-c2284a17f502 1Gi RWO Delete Bound demo/data-semi-sync-mysql-1 standard 4m35s
pvc-94f1c312-50e3-41e1-94a8-a820be0abc08 1Gi RWO Delete Bound demo/data-semi-sync-mysql-2 standard 4m31s
$ kubectl get service -n demo
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
semi-sync-mysql ClusterIP 10.96.121.252 <none> 3306/TCP 10m
semi-sync-mysql-pods ClusterIP None <none> 3306/TCP,2380/TCP,2379/TCP 10m
semi-sync-mysql-standby ClusterIP 10.96.133.61 <none> 3306/TCP 10m
KubeDB operator sets the status.phase to Ready once the database is successfully provisioned. Run the following command to see the modified MySQL object:
$ kubectl get mysql -n demo
NAME VERSION STATUS AGE
semi-sync-mysql 8.0.35 Ready 16m
$ kubectl get my -n demo semi-sync-mysql -o yaml | kubectl neat
apiVersion: kubedb.com/v1
kind: MySQL
metadata:
name: semi-sync-mysql
namespace: demo
spec:
allowedReadReplicas:
namespaces:
from: Same
allowedSchemas:
namespaces:
from: Same
authSecret:
name: semi-sync-mysql-auth
autoOps: {}
healthChecker:
failureThreshold: 1
periodSeconds: 10
timeoutSeconds: 10
podTemplate:
...
replicas: 3
storage:
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 1Gi
storageClassName: standard
storageType: Durable
deletionPolicy: WipeOut
topology:
mode: SemiSync
semiSync:
errantTransactionRecoveryPolicy: PseudoTransaction
sourceTimeout: 23h0m0s
sourceWaitForReplicaCount: 1
useAddressType: DNS
version: 8.0.35
status:
conditions:
...
observedGeneration: 2
phase: Ready
Connect with MySQL database
KubeDB operator has created a new Secret called semi-sync-mysql-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 semi-sync-mysql-auth -o jsonpath='{.data.\username}' | base64 -d
root
$ kubectl get secrets -n demo semi-sync-mysql-auth -o jsonpath='{.data.\password}' | base64 -d
y~EC~984Et1Yfs~i
The operator creates a cluster according to the newly created MySQL object. This cluster 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=semi-sync-mysql
NAME READY STATUS RESTARTS AGE
semi-sync-mysql-0 2/2 Running 0 21m
semi-sync-mysql-1 2/2 Running 0 20m
semi-sync-mysql-2 2/2 Running 0 20m
# get the governing service
$ kubectl get service semi-sync-mysql-pods -n demo
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
semi-sync-mysql-pods ClusterIP None <none> 3306/TCP,2380/TCP,2379/TCP 21m
# list the pods with PodIP
$ kubectl get pods -n demo -l app.kubernetes.io/instance=semi-sync-mysql -o jsonpath='{range.items[*]}{.metadata.name} ........... {.status.podIP} ............ {.metadata.name}.semi-sync-mysql-pods.{.metadata.namespace}{"\\n"}{end}'
semi-sync-mysql-0 ........... 10.244.0.18 ............ semi-sync-mysql-0.semi-sync-mysql-pods.demo
semi-sync-mysql-1 ........... 10.244.0.20 ............ semi-sync-mysql-1.semi-sync-mysql-pods.demo
semi-sync-mysql-2 ........... 10.244.0.22 ............ semi-sync-mysql-2.semi-sync-mysql-pods.demo
Now you can connect to these 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 semi-sync-mysql-0 -c mysql -- mysql -u root --password='y~EC~984Et1Yfs~i' --host=semi-sync-mysql-0.semi-sync-mysql-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 semi-sync-mysql-0 -c mysql -- mysql -u root --password='y~EC~984Et1Yfs~i' --host=semi-sync-mysql-1.semi-sync-mysql-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 semi-sync-mysql-0 -c mysql -- mysql -u root --password='y~EC~984Et1Yfs~i' --host=semi-sync-mysql-2.semi-sync-mysql-pods.demo -e "select 1;"
mysql: [Warning] Using a password on the command line interface can be insecure.
+---+
| 1 |
+---+
| 1 |
+---+
Check the Semi-sync cluster Status
Now, you are ready to check newly created semi-sync. Connect and run the following commands from any of the hosts and you will get the same results.
$ kubectl get pods -n demo --show-labels
NAME READY STATUS RESTARTS AGE LABELS
semi-sync-mysql-0 2/2 Running 0 171m app.kubernetes.io/component=database,app.kubernetes.io/instance=semi-sync-mysql,app.kubernetes.io/managed-by=kubedb.com,app.kubernetes.io/name=mysqls.kubedb.com,controller-revision-hash=semi-sync-mysql-77775485f8,kubedb.com/role=primary,petset.kubernetes.io/pod-name=semi-sync-mysql-0
semi-sync-mysql-1 2/2 Running 0 170m app.kubernetes.io/component=database,app.kubernetes.io/instance=semi-sync-mysql,app.kubernetes.io/managed-by=kubedb.com,app.kubernetes.io/name=mysqls.kubedb.com,controller-revision-hash=semi-sync-mysql-77775485f8,kubedb.com/role=standby,petset.kubernetes.io/pod-name=semi-sync-mysql-1
semi-sync-mysql-2 2/2 Running 0 169m app.kubernetes.io/component=database,app.kubernetes.io/instance=semi-sync-mysql,app.kubernetes.io/managed-by=kubedb.com,app.kubernetes.io/name=mysqls.kubedb.com,controller-revision-hash=semi-sync-mysql-77775485f8,kubedb.com/role=standby,petset.kubernetes.io/pod-name=semi-sync-mysql-2
From the labels we can see that the `semi-sync-mysql-0` is running as primary and the rest are running as standby.Lets validate with the mysql semisync status
$ kubectl exec -it -n demo semi-sync-mysql-0 -c mysql -- mysql -u root --password='y~EC~984Et1Yfs~i' --host=semi-sync-mysql-0.semi-sync-mysql-pods.demo -e "show status like 'Rpl%_status';"
mysql: [Warning] Using a password on the command line interface can be insecure.
+-----------------------------+-------+
| Variable_name | Value |
+-----------------------------+-------+
| Rpl_semi_sync_master_status | ON |
| Rpl_semi_sync_slave_status | OFF |
+-----------------------------+-------+
$ kubectl exec -it -n demo semi-sync-mysql-0 -c mysql -- mysql -u root --password='y~EC~984Et1Yfs~i' --host=semi-sync-mysql-1.semi-sync-mysql-pods.demo -e "show status like 'Rpl%_status';"
mysql: [Warning] Using a password on the command line interface can be insecure.
+-----------------------------+-------+
| Variable_name | Value |
+-----------------------------+-------+
| Rpl_semi_sync_master_status | OFF |
| Rpl_semi_sync_slave_status | ON |
+-----------------------------+-------+
$ kubectl exec -it -n demo semi-sync-mysql-0 -c mysql -- mysql -u root --password='y~EC~984Et1Yfs~i' --host=semi-sync-mysql-2.semi-sync-mysql-pods.demo -e "show status like 'Rpl%_status';"
mysql: [Warning] Using a password on the command line interface can be insecure.
+-----------------------------+-------+
| Variable_name | Value |
+-----------------------------+-------+
| Rpl_semi_sync_master_status | OFF |
| Rpl_semi_sync_slave_status | ON |
+-----------------------------+-------+
Data Availability
In a MySQL semi-sync 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 semi-sync-mysql-0 -- mysql -u root --password='y~EC~984Et1Yfs~i' --host=semi-sync-mysql-0.semi-sync-mysql-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 semi-sync-mysql-0 -- mysql -u root --password='y~EC~984Et1Yfs~i' --host=semi-sync-mysql-0.semi-sync-mysql-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 semi-sync-mysql-0 -c mysql -- mysql -u root --password='y~EC~984Et1Yfs~i' --host=semi-sync-mysql-0.semi-sync-mysql-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 semi-sync-mysql-0 -c mysql -- mysql -u root --password='y~EC~984Et1Yfs~i' --host=semi-sync-mysql-0.semi-sync-mysql-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 semi-sync-mysql-0 -c mysql -- mysql -u root --password='y~EC~984Et1Yfs~i' --host=semi-sync-mysql-1.semi-sync-mysql-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 semi-sync-mysql-0 -c mysql -- mysql -u root --password='y~EC~984Et1Yfs~i' --host=semi-sync-mysql-2.semi-sync-mysql-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 semi-sync-mysql-0 -c mysql -- mysql -u root --password='y~EC~984Et1Yfs~i' --host=semi-sync-mysql-1.semi-sync-mysql-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 semi-sync-mysql-0 -c mysql -- mysql -u root --password='y~EC~984Et1Yfs~i' --host=semi-sync-mysql-2.semi-sync-mysql-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 semi-sync-mysql-0
$ kubectl delete pod semi-sync-mysql-0 -n demo
pod "semi-sync-mysql-0" deleted
# check the new primary ID
$ kubectl get pod -n demo --show-labels | grep primary
semi-sync-mysql-1 2/2 Running 0 3h9m app.kubernetes.io/component=database,app.kubernetes.io/instance=semi-sync-mysql,app.kubernetes.io/managed-by=kubedb.com,app.kubernetes.io/name=mysqls.kubedb.com,controller-revision-hash=semi-sync-mysql-77775485f8,kubedb.com/role=primary,petset.kubernetes.io/pod-name=semi-sync-mysql-1
# now check the cluster status
$ kubectl exec -it -n demo semi-sync-mysql-0 -c mysql -- mysql -u root --password='y~EC~984Et1Yfs~i' --host=semi-sync-mysql-0.semi-sync-mysql-pods.demo -e "show status like 'Rpl%_status';"
mysql: [Warning] Using a password on the command line interface can be insecure.
+-----------------------------+-------+
| Variable_name | Value |
+-----------------------------+-------+
| Rpl_semi_sync_master_status | OFF |
| Rpl_semi_sync_slave_status | ON |
+-----------------------------+-------+
$ kubectl exec -it -n demo semi-sync-mysql-0 -c mysql -- mysql -u root --password='y~EC~984Et1Yfs~i' --host=semi-sync-mysql-1.semi-sync-mysql-pods.demo -e "show status like 'Rpl%_status';"
mysql: [Warning] Using a password on the command line interface can be insecure.
+-----------------------------+-------+
| Variable_name | Value |
+-----------------------------+-------+
| Rpl_semi_sync_master_status | ON |
| Rpl_semi_sync_slave_status | OFF |
+-----------------------------+-------+
$ kubectl exec -it -n demo semi-sync-mysql-0 -c mysql -- mysql -u root --password='y~EC~984Et1Yfs~i' --host=semi-sync-mysql-2.semi-sync-mysql-pods.demo -e "show status like 'Rpl%_status';"
mysql: [Warning] Using a password on the command line interface can be insecure.
+-----------------------------+-------+
| Variable_name | Value |
+-----------------------------+-------+
| Rpl_semi_sync_master_status | OFF |
| Rpl_semi_sync_slave_status | ON |
# read data from new primary semi-sync-mysql-1.semi-sync-mysql-pods.demo
$ kubectl exec -it -n demo semi-sync-mysql-0 -c mysql -- mysql -u root --password='y~EC~984Et1Yfs~i' --host=semi-sync-mysql-1.semi-sync-mysql-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 consistant.
# read data from secondary-1 semi-sync-mysql-0.semi-sync-mysql-pods.demo
$ kubectl exec -it -n demo semi-sync-mysql-0 -c mysql -- mysql -u root --password='y~EC~984Et1Yfs~i' --host=semi-sync-mysql-0.semi-sync-mysql-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 semi-sync-mysql-2.semi-sync-mysql-pods.demo
$ kubectl exec -it -n demo semi-sync-mysql-0 -c mysql -- mysql -u root --password='y~EC~984Et1Yfs~i' --host=semi-sync-mysql-2.semi-sync-mysql-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/semi-sync-mysql
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.