Modify Redis Parameters

Database reconfiguration involves modifying parameters, settings, or configurations to optimize performance, security, or availability. Parameter changes fall into two categories:

For static parameters, KubeBlocks minimizes downtime by:

1. Modifying and restarting replica nodes first
2. Performing a switchover to promote the updated replica as primary (typically completes in milliseconds)
3. Restarting the original primary node

This guide demonstrates how to modify static parameters of a Redis cluster managed by KubeBlocks using a Reconfiguring OpsRequest.

Prerequisites

Before proceeding, ensure the following:

• Environment Setup:
  • A Kubernetes cluster is up and running.
  • The kubectl CLI tool is configured to communicate with your cluster.
  • KubeBlocks CLI and KubeBlocks Operator are installed. Follow the installation instructions here.
• Namespace Preparation: To keep resources isolated, create a dedicated namespace for this tutorial:

kubectl create ns demo
namespace/demo created

Deploy a Redis Cluster

KubeBlocks uses a declarative approach for managing Redis Replication Clusters. Below is an example configuration for deploying a Redis Replication Cluster with two components, redis and redis sentinel.

Apply the following YAML configuration to deploy the cluster:

apiVersion: apps.kubeblocks.io/v1
kind: Cluster
metadata:
  name: redis-replication
  namespace: demo
spec:
  terminationPolicy: Delete
  clusterDef: redis
  topology: replication
  componentSpecs:
    - name: redis
      serviceVersion: "7.2.4"
      disableExporter: false
      replicas: 2
      resources:
        limits:
          cpu: '0.5'
          memory: 0.5Gi
        requests:
          cpu: '0.5'
          memory: 0.5Gi
      volumeClaimTemplates:
        - name: data
          spec:
            storageClassName: ""
            accessModes:
              - ReadWriteOnce
            resources:
              requests:
                storage: 20Gi
    - name: redis-sentinel
      replicas: 3
      resources:
        limits:
          cpu: '0.5'
          memory: 0.5Gi
        requests:
          cpu: '0.5'
          memory: 0.5Gi
      volumeClaimTemplates:
        - name: data
          spec:
            storageClassName: ""
            accessModes:
              - ReadWriteOnce
            resources:
              requests:
                storage: 20Gi

Verifying the Deployment

Monitor the cluster status until it transitions to the Running state:

kubectl get cluster redis-replication -n demo -w

Expected Output:

NAME                CLUSTER-DEFINITION   TERMINATION-POLICY   STATUS    AGE
redis-replication   redis                Delete               Running   3m49s

Check the pod status and roles:

kubectl get pods -l app.kubernetes.io/instance=redis-replication -L  kubeblocks.io/role -n demo

Expected Output:

NAME                                 READY   STATUS    RESTARTS   AGE     ROLE
redis-replication-redis-0            3/3     Running   0          3m38s   primary
redis-replication-redis-1            3/3     Running   0          3m16s   secondary
redis-replication-redis-sentinel-0   2/2     Running   0          4m35s
redis-replication-redis-sentinel-1   2/2     Running   0          4m17s
redis-replication-redis-sentinel-2   2/2     Running   0          3m59s

Once the cluster status becomes Running, your Redis cluster is ready for use.

Check Parameter Values

Retrieve Credentials

KubeBlocks automatically creates a secret containing the Redis root credentials. Retrieve the credentials with the following commands:

NAME=`kubectl get secrets -n demo redis-replication-redis-account-default -o jsonpath='{.data.username}' | base64 -d`
PASSWD=`kubectl get secrets -n demo redis-replication-redis-account-default -o jsonpath='{.data.password}' | base64 -d`

Access Redis Cluster

To connect to the cluster's primary node, use the Redis client:

kubectl exec -it -n demo redis-replication-redis-0 -c redis -- redis-cli -a ${PASSWD}

Query Parameter Values

Once connected, you can query the current value of 'max_connections' and 'shared_buffers':

127.0.0.1:6379> CONFIG GET aof-timestamp-enabled
1) "aof-timestamp-enabled"
2) "no"

Static Parameter Example: Modifying aof-timestamp-enabled

Create a Reconfigure OpsRequest. Apply the following OpsRequest YAML to set the 'aof-timestamp-enabled' to 'yes':

apiVersion: operations.kubeblocks.io/v1alpha1
kind: OpsRequest
metadata:
  name: redis-reconfigure-static
  namespace: demo
spec:
  clusterName: redis-replication
  reconfigures:
  - componentName: redis
    parameters:
    - key: aof-timestamp-enabled
      value: 'yes'
  type: Reconfiguring

Check the status of the OpsRequest until it completes:

kubectl get ops redis-reconfigure-static -n demo -w

Example Output:

redis-reconfigure-static   Reconfiguring   redis-replication   Running   -/-        5s
redis-reconfigure-static   Reconfiguring   redis-replication   Succeed   -/-        33s

Verify the Configuration Change

Log into the Redis instance and confirm that the aof-timestamp-enabled parameter has been updated:

127.0.0.1:6379> CONFIG GET aof-timestamp-enabled
1) "aof-timestamp-enabled"
2) "yes"

Cleanup

To remove all created resources, delete the Redis cluster along with its namespace:

kubectl delete cluster redis-replication -n demo
kubectl delete ns demo

Summary

This guide covered modifying Redis parameters through KubeBlocks:

• Static changes require restart but with minimal downtime
• All changes are validated before application
• Configuration follows declarative management principles