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Reconfigure MariaDB Cluster Database

This guide will show you how to use KubeDB Enterprise operator to reconfigure a MariaDB Cluster.

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.
Install KubeDB Community and Enterprise operator in your cluster following the steps here.
You should be familiar with the following KubeDB concepts:

To keep everything isolated, we are going to use a separate namespace called demo throughout this tutorial.

$ kubectl create ns demo
namespace/demo created

Now, we are going to deploy a MariaDB Cluster using a supported version by KubeDB operator. Then we are going to apply MariaDBOpsRequest to reconfigure its configuration.

Prepare MariaDB Cluster

Now, we are going to deploy a MariaDB Cluster database with version 10.5.8.

Deploy MariaDB

At first, we will create md-config.cnf file containing required configuration settings.

$ cat md-config.cnf 
[mysqld]
max_connections = 200
read_buffer_size = 1048576

Here, max_connections is set to 200, whereas the default value is 151. Likewise, read_buffer_size has the deafult value 131072.

Now, we will create a secret with this configuration file.

$ kubectl create secret generic -n demo md-configuration --from-file=./md-config.cnf
secret/md-configuration created

In this section, we are going to create a MariaDB object specifying spec.configSecret field to apply this custom configuration. Below is the YAML of the MariaDB CR that we are going to create,

apiVersion: kubedb.com/v1alpha2
kind: MariaDB
metadata:
  name: sample-mariadb
  namespace: demo
spec:
  version: "10.5.8"
  replicas: 3
  configSecret:
    name: md-configuration
  storageType: Durable
  storage:
    storageClassName: "standard"
    accessModes:
    - ReadWriteOnce
    resources:
      requests:
        storage: 1Gi
  terminationPolicy: WipeOut

Let’s create the MariaDB CR we have shown above,

$ kubectl create -f https://github.com/kubedb/docs/raw/v2022.03.28/docs/guides/mariadb/reconfigure/cluster/examples/sample-mariadb-config.yaml
mariadb.kubedb.com/sample-mariadb created

Now, wait until sample-mariadb has status Ready. i.e,

$ kubectl get mariadb -n demo 
NAME             VERSION   STATUS   AGE
sample-mariadb   10.5.8    Ready    71s

Now, we will check if the database has started with the custom configuration we have provided.

First we need to get the username and password to connect to a mariadb instance,

$ kubectl get secrets -n demo sample-mariadb-auth -o jsonpath='{.data.\username}' | base64 -d                                                                       
root

$ kubectl get secrets -n demo sample-mariadb-auth -o jsonpath='{.data.\password}' | base64 -d                                                                         
nrKuxni0wDSMrgwy

Now, we will check if the database has started with the custom configuration we have provided.

$ 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

As we can see from the configuration of ready mariadb, the value of max_connections has been set to 200 and read_buffer_size has been set to 1048576.

Reconfigure using new config secret

Now we will reconfigure this database to set max_connections to 250 and read_buffer_size to 122880.

Now, we will create new file new-md-config.cnf containing required configuration settings.

$ cat new-md-config.cnf 
[mysqld]
max_connections = 250
read_buffer_size = 122880

Then, we will create a new secret with this configuration file.

$ kubectl create secret generic -n demo new-md-configuration --from-file=./new-md-config.cnf
secret/new-md-configuration created

Create MariaDBOpsRequest

Now, we will use this secret to replace the previous secret using a MariaDBOpsRequest CR. The MariaDBOpsRequest yaml is given below,

apiVersion: ops.kubedb.com/v1alpha1
kind: MariaDBOpsRequest
metadata:
  name: mdops-reconfigure-config
  namespace: demo
spec:
  type: Reconfigure
  databaseRef:
    name: sample-mariadb
  configuration:   
    configSecret:
      name: new-md-configuration

Here,

spec.databaseRef.name specifies that we are reconfiguring mdops-reconfigure-config database.
spec.type specifies that we are performing Reconfigure on our database.
spec.configuration.configSecret.name specifies the name of the new secret.

Let’s create the MariaDBOpsRequest CR we have shown above,

$ kubectl apply -f https://github.com/kubedb/docs/raw/v2022.03.28/docs/guides/mariadb/reconfigure/cluster/examples/reconfigure-using-secret.yaml
mariadbopsrequest.ops.kubedb.com/mdops-reconfigure-config created

Verify the new configuration is working

If everything goes well, KubeDB Enterprise operator will update the configSecret of MariaDB object.

Let’s wait for MariaDBOpsRequest to be Successful. Run the following command to watch MariaDBOpsRequest CR,

$ kubectl get mariadbopsrequest --all-namespaces
NAMESPACE   NAME                       TYPE          STATUS       AGE
demo        mdops-reconfigure-config   Reconfigure   Successful   3m8s

We can see from the above output that the MariaDBOpsRequest has succeeded. If we describe the MariaDBOpsRequest we will get an overview of the steps that were followed to reconfigure the database.

$ kubectl describe mariadbopsrequest -n demo mdops-reconfigure-config
Name:         mdops-reconfigure-config
Namespace:    demo
Labels:       <none>
Annotations:  API Version:  ops.kubedb.com/v1alpha1
Kind:         MariaDBOpsRequest
Metadata:
  ...
  Resource Version:  71713
  UID:               6978da49-b29e-42ec-b137-ba42d3f2868d
Spec:
  Configuration:
    Config Secret:
      Name:  new-md-config
  Database Ref:
    Name:  sample-mariadb
  Type:    Reconfigure
Status:
  Conditions:
    Last Transition Time:  2022-01-10T12:06:02Z
    Message:               Controller has started to Progress the MariaDBOpsRequest: demo/mdops-reconfigure-config
    Observed Generation:   1
    Reason:                OpsRequestProgressingStarted
    Status:                True
    Type:                  Progressing
    Last Transition Time:  2022-01-10T12:13:57Z
    Message:               Successfully reconfigured MariaDB pod for MariaDBOpsRequest: demo/mdops-reconfigure-config 
    Observed Generation:   1
    Reason:                SuccessfullyDBReconfigured
    Status:                True
    Type:                  Reconfigure
    Last Transition Time:  2022-01-10T12:13:57Z
    Message:               Controller has successfully reconfigure the MariaDB demo/mdops-reconfigure-config
    Observed Generation:   1
    Reason:                OpsRequestProcessedSuccessfully
    Status:                True
    Type:                  Successful
  Observed Generation:     3
  Phase:                   Successful
  ...

Now let’s connect to a mariadb instance and run a mariadb internal command to check the new configuration we have provided.

$ 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 | 250   |
+-----------------+-------+
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 | 122880  |
+------------------+---------+
1 row in set (0.001 sec)

MariaDB [(none)]> exit
Bye

As we can see from the configuration has changed, the value of max_connections has been changed from 200 to 250 and so as the read_buffer_size. So the reconfiguration of the database is successful.

Remove Custom Configuration

We can also remove exisiting custom config using MariaDBOpsRequest. Provide true to field spec.configuration.removeCustomConfig and make an Ops Request to remove existing custom configuration.

Create MariaDBOpsRequest

Lets create an MariaDBOpsRequest having spec.configuration.removeCustomConfig is equal true,

apiVersion: ops.kubedb.com/v1alpha1
kind: MariaDBOpsRequest
metadata:
  name: mdops-reconfigure-remove
  namespace: demo
spec:
  type: Reconfigure
  databaseRef:
    name: sample-mariadb
  configuration:   
    removeCustomConfig: true

Here,

spec.databaseRef.name specifies that we are reconfiguring mdops-reconfigure-remove database.
spec.type specifies that we are performing Reconfigure on our database.
spec.configuration.removeCustomConfig is a bool field that should be true when you want to remove existing custom configuration.

Let’s create the MariaDBOpsRequest CR we have shown above,

$ kubectl apply -f https://github.com/kubedb/docs/raw/v2022.03.28/docs/guides/mariadb/reconfigure/cluster/examples/reconfigure-remove.yaml
mariadbopsrequest.ops.kubedb.com/mdops-reconfigure-remove created

Verify the new configuration is working

If everything goes well, KubeDB Enterprise operator will update the configSecret of MariaDB object.

Let’s wait for MariaDBOpsRequest to be Successful. Run the following command to watch MariaDBOpsRequest CR,

$ kubectl get mariadbopsrequest --all-namespaces
NAMESPACE   NAME                       TYPE          STATUS       AGE
demo        mdops-reconfigure-remove   Reconfigure   Successful   3m8s

Now let’s connect to a mariadb instance and run a mariadb internal command to check the new configuration we have provided.

$ 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 | 151   |
+-----------------+-------+
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 | 131072  |
+------------------+---------+
1 row in set (0.001 sec)

MariaDB [(none)]> exit
Bye

As we can see from the configuration has changed to its default value. So removal of existing custom configuration using MariaDBOpsRequest is successful.

Cleaning Up

To clean up the Kubernetes resources created by this tutorial, run:

$ kubectl delete mariadb -n demo sample-mariadb
$ kubectl delete mariadbopsrequest -n demo mdops-reconfigure-config mdops-reconfigure-remove

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Reconfigure MariaDB Cluster Database

Before You Begin

Prepare MariaDB Cluster

Deploy MariaDB

Reconfigure using new config secret

Create MariaDBOpsRequest

Verify the new configuration is working

Remove Custom Configuration

Create MariaDBOpsRequest

Verify the new configuration is working

Cleaning Up

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