Kubernetes Redis Cluster issue - redis

Question

I'm trying to create redis cluster using kubernetes on centos. I have my kubernetes master running on one host and kubernetes slaves on 2 different hosts.
etcdctl get /kube-centos/network/config
{ "Network": "172.30.0.0/16", "SubnetLen": 24, "Backend": { "Type": "vxlan" } }
Here is my replication controller
apiVersion: v1
kind: ReplicationController
metadata:
name: redis-master
labels:
app: redis
role: master
tier: backend
spec:
replicas: 6
template:
metadata:
labels:
app: redis
role: master
tier: backend
spec:
containers:
- name: master
image: redis
command:
- "redis-server"
args:
- "/redis-master/redis.conf"
ports:
- containerPort: 6379
volumeMounts:
- mountPath: /redis-master
name: config
- mountPath: /redis-master-data
name: data
volumes:
- name: data
emptyDir: {}
- name: config
configMap:
name: redis-config
items:
- key: redis-config
path: redis.conf
kubectl create -f rc.yaml
NAME READY STATUS RESTARTS AGE IP NODE
redis-master-149tt 1/1 Running 0 8s 172.30.96.4 centos-minion-1
redis-master-14j0k 1/1 Running 0 8s 172.30.79.3 centos-minion-2
redis-master-3wgdt 1/1 Running 0 8s 172.30.96.3 centos-minion-1
redis-master-84jtv 1/1 Running 0 8s 172.30.96.2 centos-minion-1
redis-master-fw3rs 1/1 Running 0 8s 172.30.79.4 centos-minion-2
redis-master-llg9n 1/1 Running 0 8s 172.30.79.2 centos-minion-2
Redis-config file used
appendonly yes
cluster-enabled yes
cluster-config-file /redis-master/nodes.conf
cluster-node-timeout 5000
dir /redis-master
port 6379
I used the following command to create the kubernetes service.
kubectl expose rc redis-master --name=redis-service --port=6379 --target-port=6379 --type=NodePort
Name: redis-service
Namespace: default
Labels: app=redis
role=master
tier=backend
Selector: app=redis,role=master,tier=backend
Type: NodePort
IP: 10.254.229.114
Port: <unset> 6379/TCP
NodePort: <unset> 30894/TCP
Endpoints: 172.30.79.2:6379,172.30.79.3:6379,172.30.79.4:6379 + 3 more...
Session Affinity: None
No events.
Now I have all the pods and service up and running. I'm using redis-trib pod to create redis cluster.
kubectl exec -it redis-trib bash
./redis-trib.rb create --replicas 1 172.30.79.2:6379 172.30.79.3:6379 172.30.79.4:6379 172.30.96.2:6379 172.30.96.3:6379 172.30.96.4:6379
Redis Cluster created as expected with the below message.
[OK] All 16384 slots covered.
Now I should be able to access my redis-cluster on kubernetes node IP(192.168.240.116) and nodePort(30894) from any host within my network. Everything works as expected when I execute the below command from one of the kubernetes node.
redis-cli -p 30894 -h 192.168.240.116 -c
192.168.240.116:30894> set foo bar
-> Redirected to slot [12182] located at 172.30.79.4:6379
OK
172.30.79.4:6379>
When I run the same command from different (non-kubernetes) node within the same network, I see the connected timed out error.
redis-cli -c -p 30894 -h 192.168.240.116
192.168.240.116:30894> set foo bar
-> Redirected to slot [12182] located at 172.30.79.4:6379
Could not connect to Redis at 172.30.79.4:6379: Connection timed out
Is it not possible to access the redis-cluster outside the kubernetes cluster network when exposed using NodePort service type?
Also I cannot use LoadBalancer service type as I'm not hosting it on cloud.
I have been stuck with this issue for quite a while. Can someone suggest on what approach I should use to access my redis-cluster outside my network ?
Thanks

Answer 1

Running ./redis-trib.rb create --replicas 1 172.30.79.2:6379 172.30.79.3:6379 172.30.79.4:6379 172.30.96.2:6379 172.30.96.3:6379 172.30.96.4:6379 doesn't make sense with this setup.
The port 6379 is only accessible through the service which you brough up, but never directly as you try. That's why you run into issues when you try to use your setup.
What you can do is to expose each POD with it's own service and have one additional cluster services to loadbalance external requests. As shown in the example repository from Kelsey Hightower. This way the PODs can communicate though the internally exposed ports and (external) clients can use the loadbalanced cluster port. The implication then is also that each POD requires it's own ReplicaSet (or Deployment). There's a long talk available on YouTube from Kelsey explaining the setup - YouTube / Slideshare.
An alternative would be to use a single redis master as shown in other examples.