RedisClusterKubernetes

redis-cluster.yml

apiVersion: v1
kind: Secret
metadata:
  name: redis-secret
type: Opaque
stringData:
  REDIS_PASSWORD: "mypass"
---
apiVersion: v1
kind: Service
metadata:
  name: redis-headless
  labels:
    app: redis
spec:
  clusterIP: None
  selector:
    app: redis
  ports:
    - name: client
      port: 6379
      targetPort: 6379
    - name: gossip
      port: 16379
      targetPort: 16379
---
apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: redis
spec:
  serviceName: redis-headless
  replicas: 6
  selector:
    matchLabels:
      app: redis
  template:
    metadata:
      labels:
        app: redis
    spec:
      containers:
        - name: redis
          image: redis:7.2
          args:
            - "redis-server"
            - "--cluster-enabled"
            - "yes"
            - "--cluster-config-file"
            - "/data/nodes.conf"
            - "--cluster-node-timeout"
            - "5000"
            - "--appendonly"
            - "yes"
            - "--requirepass"
            - "$(REDIS_PASSWORD)"
            - "--masterauth"
            - "$(REDIS_PASSWORD)"
            - "--cluster-announce-ip"
            - "$(POD_IP)"
            - "--cluster-announce-port"
            - "6379"
            - "--cluster-announce-bus-port"
            - "16379"
          env:
            - name: POD_IP
              valueFrom:
                fieldRef:
                  fieldPath: status.podIP
            - name: REDIS_PASSWORD
              valueFrom:
                secretKeyRef:
                  name: redis-secret
                  key: REDIS_PASSWORD
          ports:
            - containerPort: 6379
              name: client
            - containerPort: 16379
              name: gossip
          volumeMounts:
            - name: data
              mountPath: /data
  volumeClaimTemplates:
    - metadata:
        name: data
      spec:
        accessModes: ["ReadWriteOnce"]
        resources:
          requests:
            storage: 100Mi
---
apiVersion: batch/v1
kind: Job
metadata:
  name: redis-cluster-init
spec:
  template:
    spec:
      restartPolicy: OnFailure
      containers:
        - name: redis-init
          image: redis:7.2
          env:
            - name: REDIS_PASSWORD
              valueFrom:
                secretKeyRef:
                  name: redis-secret
                  key: REDIS_PASSWORD
          command:
            - sh
            - -c
            - |
              echo "Waiting for Redis pods..."
              sleep 20
              yes yes | redis-cli --cluster create \
                redis-0.redis-headless:6379 \
                redis-1.redis-headless:6379 \
                redis-2.redis-headless:6379 \
                redis-3.redis-headless:6379 \
                redis-4.redis-headless:6379 \
                redis-5.redis-headless:6379 \
                --cluster-replicas 1 -a ${REDIS_PASSWORD}

RedisClusterKubernetes.md

Having a redis cluster at your disposal can always come in handy!

Make sure you have a Kubernetes cluster ready.

(base) mahamudur.khan@Mac redis % kubectl get nodes

NAME             STATUS   ROLES           AGE     VERSION
docker-desktop   Ready    control-plane   4m45s   v1.32.2

We can now setup the redis cluster.

(base) mahamudur.khan@Mac redis % kubectl apply -f redis-cluster.yml 
secret/redis-secret created
service/redis-headless created
statefulset.apps/redis created
job.batch/redis-cluster-init created

Should look like this if we are successful.

(base) mahamudur.khan@Mac redis % kubectl get pods -w

NAME                       READY   STATUS    RESTARTS   AGE
redis-0                    1/1     Running   0          19s
redis-1                    1/1     Running   0          16s
redis-2                    1/1     Running   0          14s
redis-3                    1/1     Running   0          12s
redis-4                    1/1     Running   0          9s
redis-5                    1/1     Running   0          6s
redis-cluster-init-qfspk   1/1     Running   0          19s
redis-cluster-init-qfspk   0/1     Completed   0          23s
redis-cluster-init-qfspk   0/1     Completed   0          24s
redis-cluster-init-qfspk   0/1     Completed   0          25s

To access locally, we nee to forward the ports.

(base) mahamudur.khan@Mac redis % kubectl port-forward redis-0 6379:6379 &
kubectl port-forward redis-1 6380:6379 &
kubectl port-forward redis-2 6381:6379 &

On Mac, add the below mapping on /etc/hosts.

##
# Host Database
#
# localhost is used to configure the loopback interface
# when the system is booting.  Do not change this entry.
##
127.0.0.1	localhost
255.255.255.255	broadcasthost
::1             localhost
127.0.0.1 redis-1
127.0.0.1 redis-2
127.0.0.1 redis-3

Finally, we can run the python script to test:

(base) mahamudur.khan@Mac redis % python testCluster.py
Connected to Redis cluster successfully!
Successfuly set test value 'khansun' for key 'rediscluster'

testCluster.py

from rediscluster import RedisCluster

STARTUP_NODES = [
    {"host": "127.0.0.1", "port": 6379},
    {"host": "127.0.0.1", "port": 6380},
    {"host": "127.0.0.1", "port": 6381},
]
REDIS_PASSWORD = "mypass"
TEST_KEY = "rediscluster"
TEST_VALUE = "khansun"

try:
    rc = RedisCluster(
        startup_nodes=STARTUP_NODES,
        decode_responses=True,
        skip_full_coverage_check=True,
        password=REDIS_PASSWORD,
        socket_timeout=10,
        socket_connect_timeout=10
    )
    print("Connected to Redis cluster successfully!")
    rc.set(TEST_KEY, TEST_VALUE)
    print(f"Successfuly set test value '{rc.get(TEST_KEY)}' for key '{TEST_KEY}'")
except Exception as e:
    print(f"Failed! {e}")