CKAD: Fourth Mock Challenge
- 4 mins read
Task
Build a highly available redis-cluster based on the given architecture diagram.
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:
Label node01 for affinity
➜ kubectl label node node01 app=redis-cluster
node/node01 labeled
➜ kubectl get nodes --show-labels
NAME STATUS ROLES AGE VERSION LABELS
controlplane Ready control-plane 81m v1.30.0 beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,kubernetes.io/arch=amd64,kubernetes.io/hostname=controlplane,kubernetes.io/os=linux,node-role.kubernetes.io/control-plane=,node.kubernetes.io/exclude-from-external-load-balancers=
node01 Ready <none> 81m v1.30.0 app=redis-cluster,beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,kubernetes.io/arch=amd64,kubernetes.io/hostname=node01,kubernetes.io/os=linux
Persistent volume
➜ for name in redis{01..06}; do
> kubectl create -f - <<EOF
> apiVersion: v1
kind: PersistentVolume
metadata:
name: $name
spec:
capacity:
storage: 1Gi
volumeMode: Filesystem
accessModes:
- ReadWriteOnce
hostPath:
path: /$name
type: DirectoryOrCreate
nodeAffinity:
required:
nodeSelectorTerms:
- matchExpressions:
- key: app
operator: In
values:
- redis-cluster
> EOF
> done
persistentvolume/redis01 created
persistentvolume/redis02 created
persistentvolume/redis03 created
persistentvolume/redis04 created
persistentvolume/redis05 created
persistentvolume/redis06 created
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.
Verifications
➜ kubectl get service
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kubernetes ClusterIP 172.20.0.1 <none> 443/TCP 94m
redis-cluster-service ClusterIP 172.20.157.16 <none> 6379/TCP,16379/TCP 71s
➜ kubectl get pods
NAME READY STATUS RESTARTS AGE
redis-cluster-0 1/1 Running 0 74s
redis-cluster-1 1/1 Running 0 69s
redis-cluster-2 1/1 Running 0 66s
redis-cluster-3 1/1 Running 0 63s
redis-cluster-4 1/1 Running 0 60s
redis-cluster-5 1/1 Running 0 57s
➜ kubectl get pvc
NAME STATUS VOLUME CAPACITY ACCESS MODES STORAGECLASS VOLUMEATTRIBUTESCLASS AGE
data-redis-cluster-0 Bound redis04 1Gi RWO <unset> 78s
data-redis-cluster-1 Bound redis02 1Gi RWO <unset> 73s
data-redis-cluster-2 Bound redis05 1Gi RWO <unset> 70s
data-redis-cluster-3 Bound redis03 1Gi RWO <unset> 67s
data-redis-cluster-4 Bound redis06 1Gi RWO <unset> 64s
data-redis-cluster-5 Bound redis01 1Gi RWO <unset> 61s
➜ kubectl get pv
NAME CAPACITY ACCESS MODES RECLAIM POLICY STATUS CLAIM STORAGECLASS VOLUMEATTRIBUTESCLASS REASON AGE
redis01 1Gi RWO Retain Bound default/data-redis-cluster-5 <unset> 15m
redis02 1Gi RWO Retain Bound default/data-redis-cluster-1 <unset> 15m
redis03 1Gi RWO Retain Bound default/data-redis-cluster-3 <unset> 15m
redis04 1Gi RWO Retain Bound default/data-redis-cluster-0 <unset> 15m
redis05 1Gi RWO Retain Bound default/data-redis-cluster-2 <unset> 15m
redis06 1Gi RWO Retain Bound default/data-redis-cluster-4 <unset> 15m