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KubeDB - MariaDB Cluster
This tutorial will show you how to use KubeDB to provision a MariaDB replication group in single-primary mode.
Before You Begin
Before proceeding:
Read mariadb galera cluster concept to learn about MariaDB 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
demo
throughout 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/examples/mysql folder in GitHub repository kubedb/docs.
Deploy MariaDB Cluster
The following is an example MariaDB
object which creates a multi-master MariaDB group with three members.
apiVersion: kubedb.com/v1alpha2
kind: MariaDB
metadata:
name: sample-mariadb
namespace: demo
spec:
version: "10.5.8"
replicas: 3
storageType: Durable
storage:
storageClassName: "standard"
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 1Gi
terminationPolicy: WipeOut
$ kubectl create -f https://github.com/kubedb/docs/raw/v2023.01.31/docs/guides/mariadb/clustering/galera-cluster/examples/demo-1.yaml
mariadb.kubedb.com/sample-mariadb created
Here,
spec.replicas
is the number of nodes in the cluster.spec.storage
specifies 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 MariaDB
objects using Kubernetes API. When a MariaDB
object is created, KubeDB operator will create a new StatefulSet and a Service with the matching MariaDB object name. KubeDB operator will also create a governing service for the StatefulSet with the name <mariadb-object-name>-pods
.
$ kubectl get mariadb -n demo sample-mariadb -o yaml
apiVersion: kubedb.com/v1alpha2
kind: MariaDB
metadata:
annotations:
kubectl.kubernetes.io/last-applied-configuration: |
{"apiVersion":"kubedb.com/v1alpha2","kind":"MariaDB","metadata":{"annotations":{},"name":"sample-mariadb","namespace":"demo"},"spec":{"replicas":3,"storage":{"accessModes":["ReadWriteOnce"],"resources":{"requests":{"storage":"1Gi"}},"storageClassName":"standard"},"storageType":"Durable","terminationPolicy":"WipeOut","version":"10.5.8"}}
creationTimestamp: "2021-03-16T09:39:01Z"
finalizers:
- kubedb.com
generation: 2
managedFields:
...
name: sample-mariadb
namespace: demo
spec:
authSecret:
name: sample-mariadb-auth
podTemplate:
...
replicas: 3
storage:
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 1Gi
storageClassName: standard
storageType: Durable
terminationPolicy: WipeOut
version: 10.5.8
status:
conditions:
- lastTransitionTime: "2021-03-16T09:39:01Z"
message: 'The KubeDB operator has started the provisioning of MariaDB: demo/sample-mariadb'
reason: DatabaseProvisioningStartedSuccessfully
status: "True"
type: ProvisioningStarted
- lastTransitionTime: "2021-03-16T09:40:00Z"
message: All desired replicas are ready.
reason: AllReplicasReady
status: "True"
type: ReplicaReady
- lastTransitionTime: "2021-03-16T09:39:09Z"
message: 'The MariaDB: demo/sample-mariadb is accepting client requests.'
observedGeneration: 2
reason: DatabaseAcceptingConnectionRequest
status: "True"
type: AcceptingConnection
- lastTransitionTime: "2021-03-16T09:39:50Z"
message: 'The MySQL: demo/sample-mariadb is ready.'
observedGeneration: 2
reason: ReadinessCheckSucceeded
status: "True"
type: Ready
- lastTransitionTime: "2021-03-16T09:40:00Z"
message: 'The MariaDB: demo/sample-mariadb is successfully provisioned.'
observedGeneration: 2
reason: DatabaseSuccessfullyProvisioned
status: "True"
type: Provisioned
observedGeneration: 2
phase: Ready
$ kubectl get sts,svc,secret,pvc,pv,pod -n demo
NAME READY AGE
statefulset.apps/sample-mariadb 3/3 116m
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
service/sample-mariadb ClusterIP 10.97.162.171 <none> 3306/TCP 116m
service/sample-mariadb-pods ClusterIP None <none> 3306/TCP 116m
NAME TYPE DATA AGE
secret/default-token-696cj kubernetes.io/service-account-token 3 121m
secret/sample-mariadb-auth kubernetes.io/basic-auth 2 116m
secret/sample-mariadb-token-dk4dx kubernetes.io/service-account-token 3 116m
NAME STATUS VOLUME CAPACITY ACCESS MODES STORAGECLASS AGE
persistentvolumeclaim/data-sample-mariadb-0 Bound pvc-1e259abc-5937-421a-990c-b903a83d2d8a 1Gi RWO standard 116m
persistentvolumeclaim/data-sample-mariadb-1 Bound pvc-1d0b5bcd-2699-4b87-b57b-3072ddc1027f 1Gi RWO standard 116m
persistentvolumeclaim/data-sample-mariadb-2 Bound pvc-5b85a06e-17f5-487a-9150-e928f5cf4590 1Gi RWO standard 116m
NAME CAPACITY ACCESS MODES RECLAIM POLICY STATUS CLAIM STORAGECLASS REASON AGE
persistentvolume/pvc-1d0b5bcd-2699-4b87-b57b-3072ddc1027f 1Gi RWO Delete Bound demo/data-sample-mariadb-1 standard 116m
persistentvolume/pvc-1e259abc-5937-421a-990c-b903a83d2d8a 1Gi RWO Delete Bound demo/data-sample-mariadb-0 standard 116m
persistentvolume/pvc-5b85a06e-17f5-487a-9150-e928f5cf4590 1Gi RWO Delete Bound demo/data-sample-mariadb-2 standard 116m
NAME READY STATUS RESTARTS AGE
pod/sample-mariadb-0 1/1 Running 0 116m
pod/sample-mariadb-1 1/1 Running 0 116m
pod/sample-mariadb-2 1/1 Running 0 116m
Connect with MariaDB database
Once the database is in running state we can conncet to each of three nodes. We will use login credentials MYSQL_ROOT_USERNAME
and MYSQL_ROOT_PASSWORD
saved as container’s environment variable.
# First Node
$ kubectl exec -it -n demo sample-mariadb-0 -- bash
root@sample-mariadb-0:/ mysql -u${MYSQL_ROOT_USERNAME} -p${MYSQL_ROOT_PASSWORD}
Welcome to the MariaDB monitor. Commands end with ; or \g.
Your MariaDB connection id is 26
Server version: 10.5.8-MariaDB-1:10.5.8+maria~focal mariadb.org binary distribution
Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
MariaDB [(none)]> SELECT 1;
+---+
| 1 |
+---+
| 1 |
+---+
1 row in set (0.000 sec)
MariaDB [(none)]> quit;
Bye
# Second Node
$ kubectl exec -it -n demo sample-mariadb-1 -- bash
root@sample-mariadb-1:/ mysql -u${MYSQL_ROOT_USERNAME} -p${MYSQL_ROOT_PASSWORD}
Welcome to the MariaDB monitor. Commands end with ; or \g.
Your MariaDB connection id is 94
Server version: 10.5.8-MariaDB-1:10.5.8+maria~focal mariadb.org binary distribution
Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
MariaDB [(none)]> SELECT 1;
+---+
| 1 |
+---+
| 1 |
+---+
1 row in set (0.000 sec)
MariaDB [(none)]> quit;
Bye
# Third Node
$ kubectl exec -it -n demo sample-mariadb-2 -- bash
root@sample-mariadb-2:/ mysql -u${MYSQL_ROOT_USERNAME} -p${MYSQL_ROOT_PASSWORD}
Welcome to the MariaDB monitor. Commands end with ; or \g.
Your MariaDB connection id is 78
Server version: 10.5.8-MariaDB-1:10.5.8+maria~focal mariadb.org binary distribution
Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
MariaDB [(none)]> SELECT 1;
+---+
| 1 |
+---+
| 1 |
+---+
1 row in set (0.000 sec)
MariaDB [(none)]> quit;
Bye
Check the Cluster Status
Now, we are ready to check newly created cluster status. Connect and run the following commands from any of the hosts and you will get the same result, that is the cluster size is three.
$ kubectl exec -it -n demo sample-mariadb-0 -- bash
root@sample-mariadb-0:/ mysql -u${MYSQL_ROOT_USERNAME} -p${MYSQL_ROOT_PASSWORD}
Welcome to the MariaDB monitor. Commands end with ; or \g.
Your MariaDB connection id is 137
Server version: 10.5.8-MariaDB-1:10.5.8+maria~focal mariadb.org binary distribution
Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
MariaDB [(none)]> show status like 'wsrep_cluster_size';
+--------------------+-------+
| Variable_name | Value |
+--------------------+-------+
| wsrep_cluster_size | 3 |
+--------------------+-------+
1 row in set (0.001 sec)
Data Availability
In a MariaDB Galera Cluster, Each member can read and write. In this section, we will insert data from any nodes, and we will see whether we can get the data from every other members.
Read the comment written for the following commands. They contain the instructions and explanations of the commands.
$ kubectl exec -it -n demo sample-mariadb-0 -- bash
root@sample-mariadb-0:/ mysql -u${MYSQL_ROOT_USERNAME} -p${MYSQL_ROOT_PASSWORD}
Welcome to the MariaDB monitor. Commands end with ; or \g.
Your MariaDB connection id is 202
Server version: 10.5.8-MariaDB-1:10.5.8+maria~focal mariadb.org binary distribution
Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
MariaDB [(none)]> CREATE DATABASE playground;
Query OK, 1 row affected (0.013 sec)
# Create table in Node 1
MariaDB [(none)]> CREATE TABLE playground.equipment ( id INT NOT NULL AUTO_INCREMENT, type VARCHAR(50), quant INT, color VARCHAR(25), PRIMARY KEY(id));
Query OK, 0 rows affected (0.053 sec)
# Insert sample data into Node 1
MariaDB [(none)]> INSERT INTO playground.equipment (type, quant, color) VALUES ('slide', 2, 'blue');
Query OK, 1 row affected (0.003 sec)
# Read data from Node 1
MariaDB [(none)]> SELECT * FROM playground.equipment;
+----+-------+-------+-------+
| id | type | quant | color |
+----+-------+-------+-------+
| 1 | slide | 2 | blue |
+----+-------+-------+-------+
1 row in set (0.001 sec)
MariaDB [(none)]> quit;
Bye
root@sample-mariadb-0:/ exit
exit
~ $ kubectl exec -it -n demo sample-mariadb-1 -- bash
root@sample-mariadb-1:/ mysql -u${MYSQL_ROOT_USERNAME} -p${MYSQL_ROOT_PASSWORD}
Welcome to the MariaDB monitor. Commands end with ; or \g.
Your MariaDB connection id is 209
Server version: 10.5.8-MariaDB-1:10.5.8+maria~focal mariadb.org binary distribution
Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
# Read data from Node 2
MariaDB [(none)]> SELECT * FROM playground.equipment;
+----+-------+-------+-------+
| id | type | quant | color |
+----+-------+-------+-------+
| 1 | slide | 2 | blue |
+----+-------+-------+-------+
1 row in set (0.001 sec)
#Insert data into node 2
MariaDB [(none)]> INSERT INTO playground.equipment (type, quant, color) VALUES ('slide', 4, 'red');
Query OK, 1 row affected (0.032 sec)
# Read data from Node 2 after insertion
MariaDB [(none)]> SELECT * FROM playground.equipment;
+----+-------+-------+-------+
| id | type | quant | color |
+----+-------+-------+-------+
| 1 | slide | 2 | blue |
| 5 | slide | 4 | red |
+----+-------+-------+-------+
2 rows in set (0.000 sec)
MariaDB [(none)]> quit;
Bye
root@sample-mariadb-1:/ exit
exit
~ $ kubectl exec -it -n demo sample-mariadb-2 -- bash
root@sample-mariadb-2:/ mysql -u${MYSQL_ROOT_USERNAME} -p${MYSQL_ROOT_PASSWORD}
Welcome to the MariaDB monitor. Commands end with ; or \g.
Your MariaDB connection id is 209
Server version: 10.5.8-MariaDB-1:10.5.8+maria~focal mariadb.org binary distribution
Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
# Insert data into Node 3
MariaDB [(none)]> INSERT INTO playground.equipment (type, quant, color) VALUES ('slide', 4, 'red');
Query OK, 1 row affected (0.005 sec)
# Read data from Node 3
MariaDB [(none)]> SELECT * FROM playground.equipment;
+----+-------+-------+-------+
| id | type | quant | color |
+----+-------+-------+-------+
| 1 | slide | 2 | blue |
| 5 | slide | 4 | red |
| 6 | slide | 4 | red |
+----+-------+-------+-------+
3 rows in set (0.000 sec)
MariaDB [(none)]> quit
Bye
root@sample-mariadb-2:/# exit
exit
Automatic Failover
To test automatic failover, we will force the one of three pods to restart and check if it can rejoin the cluster.
Read the comment written for the following commands. They contain the instructions and explanations of the commands.
kubectl exec -it -n demo sample-mariadb-0 -- bash
root@sample-mariadb-0:/ mysql -u${MYSQL_ROOT_USERNAME} -p${MYSQL_ROOT_PASSWORD}
Welcome to the MariaDB monitor. Commands end with ; or \g.
Your MariaDB connection id is 11
Server version: 10.5.8-MariaDB-1:10.5.8+maria~focal mariadb.org binary distribution
Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
# Check current data
MariaDB [(none)]> SELECT * FROM playground.equipment;
+----+-------+-------+-------+
| id | type | quant | color |
+----+-------+-------+-------+
| 1 | slide | 2 | blue |
| 5 | slide | 4 | red |
| 6 | slide | 4 | red |
+----+-------+-------+-------+
3 rows in set (0.002 sec)
MariaDB [(none)]> quit;
Bye
root@sample-mariadb-0:/ exit
exit
# Forcefully delete Node 1
~ $ kubectl delete pod -n demo sample-mariadb-0
pod "sample-mariadb-0" deleted
# Wait for sample-mariadb-0 to restart
$ kubectl exec -it -n demo sample-mariadb-0 -- bash
root@sample-mariadb-0:/ mysql -u${MYSQL_ROOT_USERNAME} -p${MYSQL_ROOT_PASSWORD}
Welcome to the MariaDB monitor. Commands end with ; or \g.
Your MariaDB connection id is 10
Server version: 10.5.8-MariaDB-1:10.5.8+maria~focal mariadb.org binary distribution
Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
# Check data after rejoining
MariaDB [(none)]> SELECT * FROM playground.equipment;
+----+-------+-------+-------+
| id | type | quant | color |
+----+-------+-------+-------+
| 1 | slide | 2 | blue |
| 5 | slide | 4 | red |
| 6 | slide | 4 | red |
+----+-------+-------+-------+
3 rows in set (0.002 sec)
# Check cluster size
MariaDB [(none)]> show status like 'wsrep_cluster_size';
+--------------------+-------+
| Variable_name | Value |
+--------------------+-------+
| wsrep_cluster_size | 3 |
+--------------------+-------+
1 row in set (0.002 sec)
MariaDB [(none)]> quit
Bye
Cleaning up
Clean what we created in this tutorial.
$ kubectl delete mariadb -n demo sample-mariadb
mariadb.kubedb.com "sample-mariadb" deleted
$ kubectl delete ns demo
namespace "demo" deleted