New to KubeDB? Please start here.
Using Custom Configuration File
KubeDB supports providing custom configuration for MariaDB. This tutorial will show you how to use KubeDB to run a MariaDB database with custom configuration.
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.
-
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.
$ kubectl create ns demo
namespace/demo created
$ kubectl get ns demo
NAME STATUS AGE
demo Active 5s
Note: YAML files used in this tutorial are stored in here folder in GitHub repository kubedb/docs.
Overview
MariaDB allows to configure database via configuration file. The default configuration for MariaDB can be found in /etc/mysql/my.cnf file. When MariaDB starts, it will look for custom configuration file in /etc/mysql/conf.d directory. If configuration file exist, MariaDB instance will use combined startup setting from both /etc/mysql/my.cnf and *.cnf files in /etc/mysql/conf.d directory. This custom configuration will overwrite the existing default one. To know more about configuring MariaDB see here.
At first, you have to create a config file with .cnf extension with your desired configuration. Then you have to put this file into a volume. You have to specify this volume in spec.configSecret section while creating MariaDB crd. KubeDB will mount this volume into /etc/mysql/conf.d directory of the database pod.
In this tutorial, we will configure max_connections and read_buffer_size via a custom config file. We will use Secret as volume source.
Custom Configuration
At first, let’s create md-config.cnf file setting max_connections and read_buffer_size parameters.
cat <<EOF > md-config.cnf
[mysqld]
max_connections = 200
read_buffer_size = 1048576
EOF
$ cat md-config.cnf
[mysqld]
max_connections = 200
read_buffer_size = 1048576
Here, read_buffer_size is set to 1MB in bytes.
Now, create a Secret with this configuration file.
$ kubectl create secret generic -n demo md-configuration --from-file=./md-config.cnf
secret/md-configuration created
Verify the Secret has the configuration file.
$ kubectl get secret -n demo md-configuration -o yaml
apiVersion: v1
stringData:
md-config.cnf: |
[mysqld]
max_connections = 200
read_buffer_size = 1048576
kind: Secret
metadata:
name: md-configuration
namespace: demo
...
Now, create MariaDB crd specifying spec.configSecret field.
$ kubectl apply -f https://github.com/kubedb/docs/raw/v2023.02.28/docs/guides/mariadb/configuration/using-config-file/examples/md-custom.yaml
mysql.kubedb.com/custom-mysql created
Below is the YAML for the MariaDB crd we just created.
apiVersion: kubedb.com/v1alpha2
kind: MariaDB
metadata:
name: sample-mariadb
namespace: demo
spec:
version: "10.5.8"
configSecret:
name: md-configuration
storageType: Durable
storage:
storageClassName: "standard"
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 1Gi
terminationPolicy: WipeOut
Now, wait a few minutes. KubeDB operator will create necessary PVC, statefulset, services, secret etc. If everything goes well, we will see that a pod with the name sample-mariadb-0 has been created.
Check that the statefulset’s pod is running
$ kubectl get pod -n demo
NAME READY STATUS RESTARTS AGE
sample-mariadb-0 1/1 Running 0 21s
$ kubectl get mariadb -n demo
NAME VERSION STATUS AGE
sample-mariadb 10.5.8 Ready 71s
We can see the database is in ready phase so it can accept conncetion.
Now, we will check if the database has started with the custom configuration we have provided.
Read the comment written for the following commands. They contain the instructions and explanations of the commands.
# Connceting to the database
$ 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 23
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.
# value of `max_conncetions` is same as provided
MariaDB [(none)]> show variables like 'max_connections';
+-----------------+-------+
| Variable_name | Value |
+-----------------+-------+
| max_connections | 200 |
+-----------------+-------+
1 row in set (0.001 sec)
# value of `read_buffer_size` is same as provided
MariaDB [(none)]> show variables like 'read_buffer_size';
+------------------+---------+
| Variable_name | Value |
+------------------+---------+
| read_buffer_size | 1048576 |
+------------------+---------+
1 row in set (0.001 sec)
MariaDB [(none)]> exit
Bye
Cleaning up
To cleanup the Kubernetes resources created by this tutorial, run:
$ kubectl delete mariadb -n demo sample-mariadb
mariadb.kubedb.com "sample-mariadb" deleted
$ kubectl delete ns demo
namespace "demo" deleted
