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Using Custom Configuration File

KubeDB supports providing custom configuration for SingleStore. This tutorial will show you how to use KubeDB to run a SingleStore 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 docs/guides/singlestore/configuration/config-file/yamls folder in GitHub repository kubedb/docs.

Overview

SingleStore allows to configure database via configuration file. The default configuration for SingleStore can be found in /var/lib/memsql/instance/memsql.cnf file. When SingleStore starts, it will look for custom configuration file in /etc/memsql/conf.d directory. If configuration file exist, SingleStore instance will use combined startup setting from both /var/lib/memsql/instance/memsql.cnf and *.cnf files in /etc/memsql/conf.d directory. This custom configuration will overwrite the existing default one. To know more about configuring SingleStore 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 need to specify this volume in the spec.configSecret section when creating the SingleStore CRD for Standalone mode. Additionally, you can modify your aggregator and leaf nodes separately by providing separate configSecrets, or use the same one in the spec.topology.aggregator.configSecret and spec.topology.leaf.configSecret sections when creating the SingleStore CRD for Cluster mode. KubeDB will mount this volume into /etc/memsql/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 configMap as volume source.

Create SingleStore License Secret

We need SingleStore License to create SingleStore Database. So, Ensure that you have acquired a license and then simply pass the license by secret.

$ kubectl create secret generic -n demo license-secret \
                --from-literal=username=license \
                --from-literal=password='your-license-set-here'
secret/license-secret created

Custom Configuration

At first, let’s create sdb-config.cnf file setting max_connections and read_buffer_size parameters.

cat <<EOF > sdb-config.cnf
[server]
max_connections = 250
read_buffer_size = 1048576
EOF

$ cat sdb-config.cnf
[server]
max_connections = 250
read_buffer_size = 122880

Now, create a secret with this configuration file.

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

Verify the secret has the configuration file.

$ kubectl get secret -n demo sdb-configuration -o yaml
apiVersion: v1
data:
  sdb-config.cnf: W3NlcnZlcl0KbWF4X2Nvbm5lY3Rpb25zID0gMjUwCnJlYWRfYnVmZmVyX3NpemUgPSAxMjI4ODAK
kind: Secret
metadata:
  creationTimestamp: "2024-10-02T12:54:35Z"
  name: sdb-configuration
  namespace: demo
  resourceVersion: "99627"
  uid: c2621d8e-ebca-4300-af05-0180512ce031
type: Opaque

Now, create SingleStore crd specifying spec.topology.aggregator.configSecret and spec.topology.leaf.configSecret field.

$ kubectl apply -f https://github.com/kubedb/docs/raw/v2024.11.8-rc.0/docs/guides/singlestore/configuration/config-file/yamls/sdb-custom.yaml
singlestore.kubedb.com/custom-sdb created

Below is the YAML for the SingleStore crd we just created.

apiVersion: kubedb.com/v1alpha2
kind: Singlestore
metadata:
  name: custom-sdb
  namespace: demo
spec:
  version: "8.7.10"
  topology:
    aggregator:
      replicas: 2
      configSecret:
        name: sdb-configuration
      podTemplate:
        spec:
          containers:
          - name: singlestore
            resources:
              limits:
                memory: "2Gi"
                cpu: "600m"
              requests:
                memory: "2Gi"
                cpu: "600m"
      storage:
        storageClassName: "standard"
        accessModes:
        - ReadWriteOnce
        resources:
          requests:
            storage: 1Gi
    leaf:
      replicas: 2
      configSecret:
        name: sdb-configuration
      podTemplate:
        spec:
          containers:
            - name: singlestore
              resources:
                limits:
                  memory: "2Gi"
                  cpu: "600m"
                requests:
                  memory: "2Gi"
                  cpu: "600m"                      
      storage:
        storageClassName: "standard"
        accessModes:
          - ReadWriteOnce
        resources:
          requests:
            storage: 10Gi
  licenseSecret:
    name: license-secret
  storageType: Durable
  deletionPolicy: WipeOut

Now, wait a few minutes. KubeDB operator will create necessary PVC, petset, services, secret etc.

Check that the petset’s pod is running

$ kubectl get pod -n demo
NAME                      READY   STATUS    RESTARTS   AGE
custom-sdb-aggregator-0   2/2     Running   0          94s
custom-sdb-aggregator-1   2/2     Running   0          88s
custom-sdb-leaf-0         2/2     Running   0          91s
custom-sdb-leaf-1         2/2     Running   0          86s

$ kubectl get sdb -n demo
NAME         TYPE                  VERSION   STATUS   AGE
custom-sdb   kubedb.com/v1alpha2   8.7.10    Ready    4m29s

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 custom-sdb-aggregator-0 -- bash
Defaulted container "singlestore" out of: singlestore, singlestore-coordinator, singlestore-init (init)
[memsql@custom-sdb-aggregator-0 /]$ memsql -uroot -p$ROOT_PASSWORD
singlestore-client: [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 208
Server version: 5.7.32 SingleStoreDB source distribution (compatible; MySQL Enterprise & MySQL Commercial)

Copyright (c) 2000, 2022, 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.

# value of `max_conncetions` is same as provided 
singlestore> show variables like 'max_connections';
+-----------------+-------+
| Variable_name   | Value |
+-----------------+-------+
| max_connections | 250   |
+-----------------+-------+
1 row in set (0.00 sec)

# value of `read_buffer_size` is same as provided
singlestore> show variables like 'read_buffer_size';
+------------------+--------+
| Variable_name    | Value  |
+------------------+--------+
| read_buffer_size | 122880 |
+------------------+--------+
1 row in set (0.00 sec)

singlestore> exit
Bye

Cleaning up

To cleanup the Kubernetes resources created by this tutorial, run:

kubectl patch -n demo my/custom-sdb -p '{"spec":{"deletionPolicy":"WipeOut"}}' --type="merge"
kubectl delete -n demo my/custom-sdb
kubectl delete ns demo

If you would like to uninstall KubeDB operator, please follow the steps here.

Next Steps