CKAD: Fourth Mock Challenge

- 3 mins read

Task

Build a highly available Redis Cluster based on the given architecture diagram.

redis-cluster

Inspect redis-cluster-configmap

➜  kubectl describe configmap redis-cluster-configmap
Name:         redis-cluster-configmap
Namespace:    default
Labels:       <none>
Annotations:  <none>

Data
====
redis.conf:
----
cluster-enabled yes
cluster-require-full-coverage no
cluster-node-timeout 15000
cluster-config-file /data/nodes.conf
cluster-migration-barrier 1
appendonly yes
protected-mode no
update-node.sh:

Persistent volume

You have to create redis01 up to redis06 volumes with 1Gi of hostPath storage.

apiVersion: v1
kind: PersistentVolume
metadata:
  name: redis06
spec:
  capacity:
    storage: 1Gi
  volumeMode: Filesystem
  accessModes:
  - ReadWriteOnce
  hostPath:
    path: /redis06
    type: DirectoryOrCreate
  nodeAffinity:
    required:
      nodeSelectorTerms:
      - matchExpressions:
        - key: app
          operator: In
          values:
          - redis

redis-cluster.yaml

apiVersion: v1
kind: Service
metadata:
  name: redis-cluster-service
  labels:
    app: redis-cluster
spec:
  ports:
  - port: 6379
    name: client
    targetPort: 6379
  - port: 16379
    name: gossip
    targetPort: 16379
  selector:
    app: redis-cluster
---
apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: redis-cluster
spec:
  selector:
    matchLabels:
      app: redis-cluster
  serviceName: redis-cluster-service
  replicas: 6
  template:
    metadata:
      labels:
        app: redis-cluster
    spec:
      containers:
      - name: redis
        image: redis:5.0.1-alpine
        command: ["/conf/update-node.sh", "redis-server", "/conf/redis.conf"]
        env:
        - name: POD_IP
          valueFrom:
            fieldRef:
              fieldPath: status.podIP
        ports:
        - containerPort: 6369
          name: client
        - containerPort: 16379
          name: gossip
        volumeMounts:
        - name: conf
          mountPath: /conf
          readOnly: false
        - name: data
          mountPath: /data
          readOnly: false
      volumes:
      - name: conf
        configMap:
          name: redis-cluster-configmap
          defaultMode: 0755
  volumeClaimTemplates:
  - metadata:
      name: data
    spec:
      accessModes: [ "ReadWriteOnce" ]
      resources:
        requests:
          storage: 1Gi

Create cluster replica

➜  kubectl exec -it redis-cluster-0 -- redis-cli --cluster create --cluster-replicas 1 $(kubectl get pods -l app=redis-cluster -o jsonpath='{range.items[*]}{.status.podIP}:6379 {end}')
>>> Performing hash slots allocation on 6 nodes...
Master[0] -> Slots 0 - 5460
Master[1] -> Slots 5461 - 10922
Master[2] -> Slots 10923 - 16383
Adding replica 172.17.1.5:6379 to 172.17.1.2:6379
Adding replica 172.17.1.6:6379 to 172.17.1.3:6379
Adding replica 172.17.1.7:6379 to 172.17.1.4:6379
M: daa27882d3e5fd34bdc8a266a33ab104e5fc14d9 172.17.1.2:6379
   slots:[0-5460] (5461 slots) master
M: a79ada8ea5d64dc1aa07c866230dcf6b110cd877 172.17.1.3:6379
   slots:[5461-10922] (5462 slots) master
M: 702406341d135a9e07273b7d5fdaa113cdd8f34a 172.17.1.4:6379
   slots:[10923-16383] (5461 slots) master
S: 432fbdfd825137ba62d59ea73d9641198d31ff71 172.17.1.5:6379
   replicates daa27882d3e5fd34bdc8a266a33ab104e5fc14d9
S: 5afabde457cff45513247f40ba12bf5e25322fb2 172.17.1.6:6379
   replicates a79ada8ea5d64dc1aa07c866230dcf6b110cd877
S: dc9ec53a9c0beccc346c2d6c636e526c263990ef 172.17.1.7:6379
   replicates 702406341d135a9e07273b7d5fdaa113cdd8f34a
Can I set the above configuration? (type 'yes' to accept): yes
>>> Nodes configuration updated
>>> Assign a different config epoch to each node
>>> Sending CLUSTER MEET messages to join the cluster
Waiting for the cluster to join
....
>>> Performing Cluster Check (using node 172.17.1.2:6379)
M: daa27882d3e5fd34bdc8a266a33ab104e5fc14d9 172.17.1.2:6379
   slots:[0-5460] (5461 slots) master
   1 additional replica(s)
S: dc9ec53a9c0beccc346c2d6c636e526c263990ef 172.17.1.7:6379
   slots: (0 slots) slave
   replicates 702406341d135a9e07273b7d5fdaa113cdd8f34a
S: 5afabde457cff45513247f40ba12bf5e25322fb2 172.17.1.6:6379
   slots: (0 slots) slave
   replicates a79ada8ea5d64dc1aa07c866230dcf6b110cd877
M: a79ada8ea5d64dc1aa07c866230dcf6b110cd877 172.17.1.3:6379
   slots:[5461-10922] (5462 slots) master
   1 additional replica(s)
M: 702406341d135a9e07273b7d5fdaa113cdd8f34a 172.17.1.4:6379
   slots:[10923-16383] (5461 slots) master
   1 additional replica(s)
S: 432fbdfd825137ba62d59ea73d9641198d31ff71 172.17.1.5:6379
   slots: (0 slots) slave
   replicates daa27882d3e5fd34bdc8a266a33ab104e5fc14d9
[OK] All nodes agree about slots configuration.
>>> Check for open slots...
>>> Check slots coverage...
[OK] All 16384 slots covered.