CODEWITHSUNDEEP
kubernetesrediskubernetes-helm
Siriphong Wanjai
Siriphong Wanjai

Reputation: 1

How to install multiple redis on the same K8S cluster?

I have installed redis in K8S Cluster via Helm with Namespace redis1 and using port 6379,26379.

And I installed another redis in the same K8S Cluster via Helm with Namespace redis2 and using port 6380,26380.

redis1 works but redis2 error :

Events:
  Type     Reason     Age                   From               Message
  ----     ------     ----                  ----               -------
  Normal   Scheduled  30m                   default-scheduler  Successfully assigned redis2/redis-redis-ha-server-0 to worker3
  Normal   Pulled     30m                   kubelet            Container image "redis:v5.0.6-alpine" already present on machine
  Normal   Created    30m                   kubelet            Created container config-init
  Normal   Started    30m                   kubelet            Started container config-init
  Normal   Pulled     29m                   kubelet            Container image "redis:v5.0.6-alpine" already present on machine
  Normal   Created    29m                   kubelet            Created container redis
  Normal   Started    29m                   kubelet            Started container redis
  Normal   Killing    28m (x2 over 29m)     kubelet            Container sentinel failed liveness probe, will be restarted
  Normal   Pulled     28m (x3 over 29m)     kubelet            Container image "redis:v5.0.6-alpine" already present on machine
  Normal   Created    28m (x3 over 29m)     kubelet            Created container sentinel
  Normal   Started    28m (x3 over 29m)     kubelet            Started container sentinel
  Warning  Unhealthy  14m (x25 over 29m)    kubelet            Liveness probe failed: dial tcp xx.xxx.x.xxx:26380: connect: connection refused
  Warning  BackOff    4m56s (x85 over 25m)  kubelet            Back-off restarting failed container

I had previously installed rabbitmq the same way before in the same cluster it works. So I hope I can use the same method with redis.

Please advise what should be done.

Upvotes: 0

Views: 1230

Answers (1)

matt_j
matt_j

Reputation: 4614

As this issue was resolved in the comments section by @David Maze, I decided to provide a Community Wiki answer just for better visibility to other community members.

Services in Kubernetes allow applications to receive traffic and can be exposed in different ways as there are different types of Kubernetes services (see: Overview of Kubernetes Services). In case of the default ClusterIP type, it exposes the Service on an internal IP (each Service also has its own IP address) in the cluster and makes the Service only reachable from within the cluster. Each Service has its own IP address, so it's okay if they listen on the same port (but each on their own IP address).

Below is a simple example to illustrate that it's possible to have two (or more) Services listening on the same port ( 80 port).

I've created two Deployments (app1 and app2) and exposed it with ClusterIP Services using the same port number:

$ kubectl create deploy app-1 --image=nginx
deployment.apps/app-1 created

$ kubectl create deploy app-2 --image=nginx
deployment.apps/app-2 created

$ kubectl expose deploy app-1 --port=80
service/app-1 exposed

$ kubectl expose deploy app-2 --port=80
service/app-2 exposed

$ kubectl get pod,svc
NAME                         READY   STATUS    RESTARTS   
pod/app-1-5d9ccdb595-x5s55   1/1     Running   0          
pod/app-2-7747dcb588-trj8d   1/1     Running   0          

NAME                 TYPE        CLUSTER-IP    EXTERNAL-IP   PORT(S)   
service/app-1        ClusterIP   10.8.12.54    <none>        80/TCP    
service/app-2        ClusterIP   10.8.11.181   <none>        80/TCP

Finally, we can check if it works as expected:

$ kubectl run test --image=nginx
pod/test created
$ kubectl exec -it test -- bash
root@test:/# curl 10.8.12.54:80
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
...
root@test:/# curl 10.8.11.181:80
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
...

Upvotes: 0

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