Exposing a memcache loadbalancer

Cloud Platform (intermediate level) posted on 15th August 2018


This is a part of the series of posts on Getting memcache up and running on Kubernetes which explained how to create your first cluster and Installing memcache with Kubernetes which installed some memcache instances on your cluster.

I recommend that you save your commands in various scripts so you can repeat them or modify them later.  

Exposing the memcache service

If you are just keeping the memcache instance private to your cluster you don't need to bother with this. However, for demo purposes, I need to expose the memcache service outside of the Kubernetes cluster. That way, I can develop a small app to test from an external development environment such as cloud9.

Creating a loadbalancer

In the world of Kubernetes, a service is the way to communicate with the pods that are running instances of your app. We already have a memcache service, created by Helm, in the previous post. This service is accessible within the cluster just by referencing its name (which Kubernetes handily maintains from its DNS service), but it can't be seen outside the cluster.

$ kubectl get service
NAME                TYPE        CLUSTER-IP    EXTERNAL-IP   PORT(S)     AGE
kubernetes          ClusterIP   10.27.240.1   <none>        443/TCP     22h
mycache-memcached   ClusterIP   None          <none>        11211/TCP   21h

What we need to do now is expose that mycache-memcached service to the outside world. For that we need to attach a loadbalancer service.
$ kubectl expose service mycache-memcached  --port=11211 --target-port=11211 --name=mc --type=LoadBalancer

After a little while, we'll see this new Loadbalancer  created with a public IP address assigned. It can take a few minutes to complete. 
$ kubectl get service
NAME                TYPE           CLUSTER-IP    EXTERNAL-IP      PORT(S)           AGE
kubernetes          ClusterIP      10.27.240.1   <none>           443/TCP           23h
mc                  LoadBalancer   10.27.244.1   35.xxx.xxx.xxx   11211:30588/TCP   47s
mycache-memcached   ClusterIP      None          <none>           11211/TCP         22h

You can now access your memcache service on the given IP address and port number. I should remind you that this service is now public and accessible so be careful how you use it. I won't bother with it for this demo, but if you are interested in how to use ssl with Kubernetes, see HTTPS ingress for Kubernetes service

Next step

Testing memcache from outside the cluster. Creating a test app for memcache on Kubernetes





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