Horizontal Scaling of Redis Cluster in Azure Kubernetes Service (AKS)

Overview

KubeDB is the Kubernetes Native Database Management Solution which simplifies and automates routine database tasks such as Provisioning, Monitoring, Upgrading, Patching, Scaling, Volume Expansion, Backup, Recovery, Failure detection, and Repair for various popular databases on private and public clouds. The databases that KubeDB supports are MongoDB, Elasticsearch, MySQL, MariaDB, Kafka, Redis, PostgreSQL, ProxySQL, Percona XtraDB, Memcached and PgBouncer. You can find the guides to all the supported databases in KubeDB . In this tutorial we will show the horizontal scaling of Redis cluster in Azure Kubernetes Service (AKS). We will cover the following steps:

  1. Install KubeDB
  2. Deploy Redis Cluster
  3. Read/Write Sample Data
  4. Horizontal Scaling of Redis Cluster

Get Cluster ID

We need the cluster ID to get the KubeDB License. To get cluster ID we can run the following command:

$ kubectl get ns kube-system -o jsonpath='{.metadata.uid}'
8e336615-0dbb-4ae8-b72f-2e7ec34c399d

Get License

Go to Appscode License Server to get the license.txt file. For this tutorial, we will use KubeDB Enterprise Edition.

License Server

Install KubeDB

We will use helm to install KubeDB. Please install helm here if it is not already installed. Now, let’s install KubeDB.

$ helm repo add appscode https://charts.appscode.com/stable/
$ helm repo update

$ helm search repo appscode/kubedb
NAME                              	CHART VERSION	APP VERSION	DESCRIPTION                                       
appscode/kubedb                   	v2023.11.2   	v2023.11.2 	KubeDB by AppsCode - Production ready databases...
appscode/kubedb-autoscaler        	v0.22.0      	v0.22.0    	KubeDB Autoscaler by AppsCode - Autoscale KubeD...
appscode/kubedb-catalog           	v2023.11.2   	v2023.11.2 	KubeDB Catalog by AppsCode - Catalog for databa...
appscode/kubedb-community         	v0.24.2      	v0.24.2    	KubeDB Community by AppsCode - Community featur...
appscode/kubedb-crds              	v2023.11.2   	v2023.11.2 	KubeDB Custom Resource Definitions                
appscode/kubedb-dashboard         	v0.13.0      	v0.13.0    	KubeDB Dashboard by AppsCode                      
appscode/kubedb-enterprise        	v0.11.2      	v0.11.2    	KubeDB Enterprise by AppsCode - Enterprise feat...
appscode/kubedb-grafana-dashboards	v2023.11.2   	v2023.11.2 	A Helm chart for kubedb-grafana-dashboards by A...
appscode/kubedb-metrics           	v2023.11.2   	v2023.11.2 	KubeDB State Metrics                              
appscode/kubedb-one               	v2023.11.2   	v2023.11.2 	KubeDB and Stash by AppsCode - Production ready...
appscode/kubedb-ops-manager       	v0.24.0      	v0.24.0    	KubeDB Ops Manager by AppsCode - Enterprise fea...
appscode/kubedb-opscenter         	v2023.11.2   	v2023.11.2 	KubeDB Opscenter by AppsCode                      
appscode/kubedb-provider-aws      	v0.0.1       	v0.0.1     	A Helm chart for KubeDB AWS Provider for Crossp...
appscode/kubedb-provider-azure    	v0.0.1       	v0.0.1     	A Helm chart for KubeDB Azure Provider for Cros...
appscode/kubedb-provider-gcp      	v0.0.1       	v0.0.1     	A Helm chart for KubeDB GCP Provider for Crossp...
appscode/kubedb-provisioner       	v0.37.0      	v0.37.0    	KubeDB Provisioner by AppsCode - Community feat...
appscode/kubedb-schema-manager    	v0.13.0      	v0.13.0    	KubeDB Schema Manager by AppsCode                 
appscode/kubedb-ui                	v2023.11.14  	0.5.0      	A Helm chart for Kubernetes                       
appscode/kubedb-ui-server         	v2021.12.21  	v2021.12.21	A Helm chart for kubedb-ui-server by AppsCode     
appscode/kubedb-webhook-server    	v0.13.0      	v0.13.0    	KubeDB Webhook Server by AppsCode  


# Install KubeDB Enterprise operator chart
$ helm install kubedb appscode/kubedb \
  --version v2023.11.2 \
  --namespace kubedb --create-namespace \
  --set kubedb-provisioner.enabled=true \
  --set kubedb-ops-manager.enabled=true \
  --set kubedb-autoscaler.enabled=true \
  --set kubedb-dashboard.enabled=true \
  --set kubedb-schema-manager.enabled=true \
  --set-file global.license=/path/to/the/license.txt

Let’s verify the installation:

$ watch kubectl get pods --all-namespaces -l "app.kubernetes.io/instance=kubedb"

NAMESPACE   NAME                                            READY   STATUS    RESTARTS   AGE
kubedb      kubedb-kubedb-autoscaler-6cdff85c7f-pdsd9       1/1     Running   0          103s
kubedb      kubedb-kubedb-dashboard-654847ddcb-q7nfh        1/1     Running   0          103s
kubedb      kubedb-kubedb-ops-manager-56c649f5df-wx8x9      1/1     Running   0          103s
kubedb      kubedb-kubedb-provisioner-58755ff9fb-gc927      1/1     Running   0          103s
kubedb      kubedb-kubedb-schema-manager-6cb57d7479-pn8zt   1/1     Running   0          103s
kubedb      kubedb-kubedb-webhook-server-689575b457-t8nzd   1/1     Running   0          103s

We can list the CRD Groups that have been registered by the operator by running the following command:

$ kubectl get crd -l app.kubernetes.io/name=kubedb
NAME                                              CREATED AT
elasticsearchautoscalers.autoscaling.kubedb.com   2023-12-05T10:47:15Z
elasticsearchdashboards.dashboard.kubedb.com      2023-12-05T10:46:22Z
elasticsearches.kubedb.com                        2023-12-05T10:46:22Z
elasticsearchopsrequests.ops.kubedb.com           2023-12-05T10:47:03Z
elasticsearchversions.catalog.kubedb.com          2023-12-05T10:45:32Z
etcds.kubedb.com                                  2023-12-05T10:46:39Z
etcdversions.catalog.kubedb.com                   2023-12-05T10:45:32Z
kafkaopsrequests.ops.kubedb.com                   2023-12-05T10:47:36Z
kafkas.kubedb.com                                 2023-12-05T10:46:40Z
kafkaversions.catalog.kubedb.com                  2023-12-05T10:45:32Z
mariadbautoscalers.autoscaling.kubedb.com         2023-12-05T10:47:15Z
mariadbdatabases.schema.kubedb.com                2023-12-05T10:45:58Z
mariadbopsrequests.ops.kubedb.com                 2023-12-05T10:47:17Z
mariadbs.kubedb.com                               2023-12-05T10:45:58Z
mariadbversions.catalog.kubedb.com                2023-12-05T10:45:32Z
memcacheds.kubedb.com                             2023-12-05T10:46:39Z
memcachedversions.catalog.kubedb.com              2023-12-05T10:45:32Z
mongodbautoscalers.autoscaling.kubedb.com         2023-12-05T10:47:15Z
mongodbdatabases.schema.kubedb.com                2023-12-05T10:45:57Z
mongodbopsrequests.ops.kubedb.com                 2023-12-05T10:47:06Z
mongodbs.kubedb.com                               2023-12-05T10:45:58Z
mongodbversions.catalog.kubedb.com                2023-12-05T10:45:32Z
mysqlautoscalers.autoscaling.kubedb.com           2023-12-05T10:47:15Z
mysqldatabases.schema.kubedb.com                  2023-12-05T10:45:57Z
mysqlopsrequests.ops.kubedb.com                   2023-12-05T10:47:13Z
mysqls.kubedb.com                                 2023-12-05T10:45:57Z
mysqlversions.catalog.kubedb.com                  2023-12-05T10:45:32Z
perconaxtradbautoscalers.autoscaling.kubedb.com   2023-12-05T10:47:15Z
perconaxtradbopsrequests.ops.kubedb.com           2023-12-05T10:47:30Z
perconaxtradbs.kubedb.com                         2023-12-05T10:46:40Z
perconaxtradbversions.catalog.kubedb.com          2023-12-05T10:45:32Z
pgbouncers.kubedb.com                             2023-12-05T10:46:40Z
pgbouncerversions.catalog.kubedb.com              2023-12-05T10:45:32Z
postgresautoscalers.autoscaling.kubedb.com        2023-12-05T10:47:15Z
postgresdatabases.schema.kubedb.com               2023-12-05T10:45:58Z
postgreses.kubedb.com                             2023-12-05T10:45:58Z
postgresopsrequests.ops.kubedb.com                2023-12-05T10:47:24Z
postgresversions.catalog.kubedb.com               2023-12-05T10:45:32Z
proxysqlautoscalers.autoscaling.kubedb.com        2023-12-05T10:47:15Z
proxysqlopsrequests.ops.kubedb.com                2023-12-05T10:47:27Z
proxysqls.kubedb.com                              2023-12-05T10:46:40Z
proxysqlversions.catalog.kubedb.com               2023-12-05T10:45:32Z
publishers.postgres.kubedb.com                    2023-12-05T10:47:39Z
redisautoscalers.autoscaling.kubedb.com           2023-12-05T10:47:15Z
redises.kubedb.com                                2023-12-05T10:46:40Z
redisopsrequests.ops.kubedb.com                   2023-12-05T10:47:20Z
redissentinelautoscalers.autoscaling.kubedb.com   2023-12-05T10:47:15Z
redissentinelopsrequests.ops.kubedb.com           2023-12-05T10:47:33Z
redissentinels.kubedb.com                         2023-12-05T10:46:40Z
redisversions.catalog.kubedb.com                  2023-12-05T10:45:32Z
subscribers.postgres.kubedb.com                   2023-12-05T10:47:43Z

Deploy Redis Cluster

Now we are going to deploy Redis cluster using KubeDB. First, let’s create a Namespace in which we will deploy the database.

$ kubectl create namespace demo
namespace/demo created

Here is the yaml of the Redis we are going to use:

apiVersion: kubedb.com/v1alpha2
kind: Redis
metadata:
  name: redis-cluster
  namespace: demo
spec:
  version: 7.2.3
  mode: Cluster
  cluster:
    master: 3
    replicas: 1
  storageType: Durable
  storage:
    resources:
      requests:
        storage: 1Gi
    storageClassName: "default"
    accessModes:
    - ReadWriteOnce
  terminationPolicy: WipeOut

Let’s save this yaml configuration into redis-cluster.yaml Then create the above Redis cluster,

$ kubectl apply -f redis-cluster.yaml
redis.kubedb.com/redis-cluster created

In this yaml,

  • we can see in the spec.version field specifies the version of Redis. Here, we are using Redis version 7.2.3. You can list the KubeDB supported versions of Redis by running $ kubectl get redisversions command.
  • Another field to notice is the spec.storageType field. This can be Durable or Ephemeral depending on the requirements of the database to be persistent or not.
  • Lastly, the spec.terminationPolicy field is Wipeout means that the database will be deleted without restrictions. It can also be “Halt”, “Delete” and “DoNotTerminate”. Learn More about Termination Policy .

Once these are handled correctly you will see that the following are created:

$ kubectl get all -n demo
NAME                         READY   STATUS    RESTARTS   AGE
pod/redis-cluster-shard0-0   1/1     Running   0          2m52s
pod/redis-cluster-shard0-1   1/1     Running   0          2m23s
pod/redis-cluster-shard1-0   1/1     Running   0          2m49s
pod/redis-cluster-shard1-1   1/1     Running   0          2m21s
pod/redis-cluster-shard2-0   1/1     Running   0          2m46s
pod/redis-cluster-shard2-1   1/1     Running   0          2m19s

NAME                         TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)    AGE
service/redis-cluster        ClusterIP   10.96.171.128   <none>        6379/TCP   2m55s
service/redis-cluster-pods   ClusterIP   None            <none>        6379/TCP   2m56s

NAME                                    READY   AGE
statefulset.apps/redis-cluster-shard0   2/2     2m52s
statefulset.apps/redis-cluster-shard1   2/2     2m49s
statefulset.apps/redis-cluster-shard2   2/2     2m46s

NAME                                               TYPE               VERSION   AGE
appbinding.appcatalog.appscode.com/redis-cluster   kubedb.com/redis   7.2.3     2m46s

NAME                             VERSION   STATUS   AGE
redis.kubedb.com/redis-cluster   7.2.3     Ready    2m56s

Let’s check if the database is ready to use,

$ kubectl get redis -n demo
NAME            VERSION   STATUS   AGE
redis-cluster   7.2.3     Ready    3m19s

We have successfully deployed Redis cluster in AKS.

Accessing Database Through CLI

To access the database through CLI, we have to get the credentials to access. Let’s export the credentials as environment variable to our current shell :

Export the Credentials

KubeDB will create Secret and Service for the database redis-cluster that we have deployed. Let’s check them by following command,

$ kubectl get secret -n demo -l=app.kubernetes.io/instance=redis-cluster
NAME                   TYPE                       DATA   AGE
redis-cluster-auth     kubernetes.io/basic-auth   2      2m9s
redis-cluster-config   Opaque                     1      2m9s

$ kubectl get service -n demo -l=app.kubernetes.io/instance=redis-cluster
NAME                 TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)    AGE
redis-cluster        ClusterIP   10.96.171.128   <none>        6379/TCP   2m9s
redis-cluster-pods   ClusterIP   None            <none>        6379/TCP   2m9s

Now, we are going to use PASSWORD to authenticate and insert some sample data. At first, let’s export the PASSWORD as environment variables to make further commands re-usable.

$ export PASSWORD=$(kubectl get secrets -n demo redis-cluster-auth -o jsonpath='{.data.\password}' | base64 -d)

Insert Sample Data

In this section, we are going to login into our Redis database pod and insert some sample data.

$ kubectl exec -it -n demo redis-cluster-shard0-0 -- redis-cli -c -a $PASSWORD
127.0.0.1:6379> set Product1 KubeDB
OK
127.0.0.1:6379> set Product2 KubeStash
OK
127.0.0.1:6379> get Product1
"KubeDB"
127.0.0.1:6379> get Product2
"KubeStash"
127.0.0.1:6379> exit

We’ve successfully inserted some sample data to our database. More information about Run & Manage Production-Grade Redis Database on Kubernetes can be found in Redis Kubernetes

Horizontal Scaling of Redis Cluster

Scale Up Replicas

Here, we are going to scale up the replicas of the Redis cluster to meet the desired number of master and replicas after scaling.

Before applying Horizontal Scaling, let’s check the current number of master and replicas,

$ kubectl get redis -n demo redis-cluster -o json | jq '.spec.cluster.master'
3

$ kubectl get redis -n demo redis-cluster -o json | jq '.spec.replicas'
1

Create RedisOpsRequest

In order to scale up the replicas, we have to create a RedisOpsRequest CR with our desired replicas. Let’s create it using this following yaml,

apiVersion: ops.kubedb.com/v1alpha1
kind: RedisOpsRequest
metadata:
  name: horizontal-scale-up
  namespace: demo
spec:
  type: HorizontalScaling
  databaseRef:
    name: redis-cluster
  horizontalScaling:
    master: 4
    replicas: 2

Here,

  • spec.databaseRef.name specifies that we are performing horizontal scaling operation on redis-cluster.
  • spec.type specifies that we are performing HorizontalScaling on our database.
  • spec.horizontalScaling.master specifies the desired master after scaling.
  • spec.horizontalScaling.replicas specifies the desired replicas after scaling.

Let’s save this yaml configuration into horizontal-scale-up.yaml and apply it,

$ kubectl apply -f horizontal-scale-up.yaml
redisopsrequest.ops.kubedb.com/horizontal-scale-up created

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

$ watch kubectl get redisopsrequest -n demo
NAME                  TYPE                STATUS       AGE
horizontal-scale-up   HorizontalScaling   Successful   5m40s

We can see from the above output that the RedisOpsRequest has succeeded. Now, we are going to verify the number of replicas,

$ kubectl get redis -n demo redis-cluster -o json | jq '.spec.cluster.master'
4

$ kubectl get redis -n demo redis-cluster -o json | jq '.spec.replicas'
2

From all the above outputs we can see that the master and the replicas is now increased to 4 and 2 successively. That means we have successfully scaled up the Redis cluster.

Scale Down Replicas

Here, we are going to scale down the replicas of the Redis cluster to meet the desired number of master and replicas after scaling.

Create RedisOpsRequest

In order to scale down the replicas, we need to create a RedisOpsRequest CR with our desired replicas. Let’s create it using this yaml,

apiVersion: ops.kubedb.com/v1alpha1
kind: RedisOpsRequest
metadata:
  name: horizontal-scale-down
  namespace: demo
spec:
  type: HorizontalScaling
  databaseRef:
    name: redis-cluster
  horizontalScaling:
    master: 3
    replicas: 1

Here,

  • spec.databaseRef.name specifies that we are performing horizontal scaling operation on redis-cluster.
  • spec.type specifies that we are performing HorizontalScaling on our database.
  • spec.horizontalScaling.master specifies the desired master after scaling.
  • spec.horizontalScaling.replicas specifies the desired replicas after scaling.

Let’s save this yaml configuration into horizontal-scale-down.yaml and apply it,

$ kubectl apply -f horizontal-scale-down.yaml
redisopsrequest.ops.kubedb.com/horizontal-scale-down created

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

$ watch kubectl get redisopsrequest -n demo
NAME                    TYPE                STATUS       AGE
horizontal-scale-down   HorizontalScaling   Successful   4m

We can see from the above output that the RedisOpsRequest has succeeded. Now, we are going to verify the number of replicas,

$ kubectl get redis -n demo redis-cluster -o json | jq '.spec.cluster.master'
3

$ kubectl get redis -n demo redis-cluster -o json | jq '.spec.replicas'
1

From all the above outputs we can see that the master and replicas of the Redis cluster is decreased to 3 and 1 successively. That means we have successfully scaled down the Redis cluster.

If you want to learn more about Production-Grade Redis you can have a look into that playlist below:

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More about Redis in Kubernetes

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