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Using Custom Configuration File
KubeDB supports providing custom configuration for PerconaXtraDB. This tutorial will show you how to use KubeDB to run a PerconaXtraDB 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
demothroughout 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
PerconaXtraDB allows to configure database via configuration file. The default configuration for PerconaXtraDB can be found in /etc/my.cnf file. KubeDB adds a new custom configuration directory /etc/mysql/custom.conf.d if it’s enabled. When PerconaXtraDB starts, it will look for custom configuration file in /etc/mysql/custom.conf.d directory. If configuration file exist, PerconaXtraDB instance will use combined startup setting from both /etc/my.cnf and *.cnf files in /etc/mysql/conf.d and /etc/mysql/custom.conf.d directory. This custom configuration will overwrite the existing default one.
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 PerconaXtraDB crd. KubeDB will mount this volume into /etc/mysql/custom.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 px-config.cnf file setting max_connections and read_buffer_size parameters.
cat <<EOF > px-config.cnf
[mysqld]
max_connections = 200
read_buffer_size = 1048576
EOF
$ cat px-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 px-configuration --from-file=./px-config.cnf
secret/md-configuration created
Verify the Secret has the configuration file.
$ kubectl get secret -n demo px-configuration -o yaml
apiVersion: v1
stringData:
px-config.cnf: |
[mysqld]
max_connections = 200
read_buffer_size = 1048576
kind: Secret
metadata:
name: px-configuration
namespace: demo
...
Now, create PerconaXtraDB crd specifying spec.configSecret field.
$ kubectl apply -f https://github.com/kubedb/docs/raw/v2023.01.17/docs/guides/percona-xtradb/configuration/using-config-file/examples/px-custom.yaml
mysql.kubedb.com/custom-mysql created
Below is the YAML for the PerconaXtraDB crd we just created.
apiVersion: kubedb.com/v1alpha2
kind: PerconaXtraDB
metadata:
name: sample-pxc
namespace: demo
spec:
version: "8.0.26"
configSecret:
name: px-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-pxc-0 has been created.
Check that the statefulset’s pod is running
$ kubectl get pod -n demo
NAME READY STATUS RESTARTS AGE
sample-pxc-0 2/2 Running 0 75m
sample-pxc-1 2/2 Running 0 95m
sample-pxc-2 2/2 Running 0 95m
$ kubectl get perconaxtradb -n demo
NAME VERSION STATUS AGE
NAME VERSION STATUS AGE
sample-pxc 8.0.26 Ready 96m
We can see the database is in ready phase so it can accept connection.
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.
# Connecting to the database
$ kubectl exec -it -n demo sample-pxc-0 -- bash
Defaulted container "perconaxtradb" out of: perconaxtradb, px-coordinator, px-init (init)
bash-4.4$ mysql -u${MYSQL_ROOT_USERNAME} -p${MYSQL_ROOT_PASSWORD}
mysql: [Warning] Using a password on the command line interface can be insecure.
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 1390
Server version: 8.0.26-16.1 Percona XtraDB Cluster (GPL), Release rel16, Revision b141904, WSREP version 26.4.3
Copyright (c) 2009-2021 Percona LLC and/or its affiliates
Copyright (c) 2000, 2021, Oracle and/or its affiliates.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql> show variables like 'max_connections';
+-----------------+-------+
| Variable_name | Value |
+-----------------+-------+
| max_connections | 200 |
+-----------------+-------+
1 row in set (0.01 sec)
# value of `read_buffer_size` is same as provided
mysql> show variables like 'read_buffer_size';
+------------------+---------+
| Variable_name | Value |
+------------------+---------+
| read_buffer_size | 1048576 |
+------------------+---------+
1 row in set (0.001 sec)
mysql> exit
Bye
Cleaning up
To cleanup the Kubernetes resources created by this tutorial, run:
$ kubectl delete perconaxtradb -n demo sample-pxc
perconaxtradb.kubedb.com "sample-pxc" deleted
$ kubectl delete ns demo
namespace "demo" deleted