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Using Custom Configuration File

KubeDB supports providing custom configuration for Redis. This tutorial will show you how to use KubeDB to run Redis 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/examples/redis folder in GitHub repository kubedb/docs.

Overview

Redis allows configuration via a config file. When redis docker image starts, it executes redis-server command. If we provide a .conf file directory as an argument of this command, Redis server will use configuration specified in the file. To know more about configuring Redis see here.

At first, you have to create a config file named redis.conf with your desired configuration. Then you have to put this file into a secret. You have to specify this secret in spec.configSecret section while creating Redis crd. KubeDB will mount this secret into /usr/local/etc/redis directory of the pod and the redis.conf file path will be sent as an argument of redis-server command.

In this tutorial, we will configure databases and maxclients via a custom config file.

Custom Configuration

At first, let’s create redis.conf file setting databases and maxclients parameters. Default value of databases is 16 and maxclients is 10000.

$ cat <<EOF >redis.conf
databases 10
maxclients 425
EOF

$ cat redis.conf
databases 10
maxclients 425

Note that config file name must be redis.conf

Now, create a Secret with this configuration file.

$ kubectl create secret generic -n demo rd-configuration --from-file=./redis.conf
secret/rd-configuration created

Verify the Secret has the configuration file.

$ kubectl get secret -n demo rd-configuration -o yaml

apiVersion: v1
data:
  redis.conf: ZGF0YWJhc2VzIDEwCm1heGNsaWVudHMgNDI1Cgo=
kind: Secret
metadata:
  creationTimestamp: "2023-02-06T08:55:14Z"
  name: rd-configuration
  namespace: demo
  resourceVersion: "676133"
  uid: 73c4e8b5-9e9c-45e6-8b83-b6bc6f090663
type: Opaque

The configurations are encrypted in the secret.

Now, create Redis crd specifying spec.configSecret field.

$ kubectl apply -f https://github.com/kubedb/docs/raw/v2023.12.21/docs/examples/redis/custom-config/redis-custom.yaml
redis.kubedb.com "custom-redis" created

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

apiVersion: kubedb.com/v1alpha2
kind: Redis
metadata:
  name: custom-redis
  namespace: demo
spec:
  version: 6.2.14
  configSecret:
    name: rd-configuration
  storage:
    storageClassName: "standard"
    accessModes:
      - ReadWriteOnce
    resources:
      requests:
        storage: 1Gi

Now, wait a few minutes. KubeDB operator will create necessary statefulset, services etc. If everything goes well, we will see that a pod with the name custom-redis-0 has been created.

Check if the database is ready

$ kubectl get redis -n demo
NAME           VERSION   STATUS   AGE
custom-redis   6.2.14     Ready    10m

Now, we will check if the database has started with the custom configuration we have provided. We will exec into the pod and use CONFIG GET command to check the configuration.

$ kubectl exec -it -n demo custom-redis-0 -- bash
root@custom-redis-0:/data# redis-cli
127.0.0.1:6379> ping
PONG
127.0.0.1:6379> config get databases
1) "databases"
2) "10"
127.0.0.1:6379> config get maxclients
1) "maxclients"
2) "425"
127.0.0.1:6379> exit
root@custom-redis-0:/data# 

Cleaning up

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

$ kubectl patch -n demo rd/custom-redis -p '{"spec":{"terminationPolicy":"WipeOut"}}' --type="merge"
redis.kubedb.com/custom-redis patched

$ kubectl delete -n demo redis custom-redis
redis.kubedb.com "custom-redis" deleted

$ kubectl delete -n demo secret rd-configuration
secret "rd-configuration" deleted

$ kubectl delete ns demo
namespace "demo" deleted

Next Steps

• Learn how to use KubeDB to run a Redis server here.