Most folks have been using Grafana or something similar to monitor Kubernaties cluster.
If you are using Google cloud container engine , then the standard unified place to monitor all your application and services is Slackdriver.
According to googles documentation, when you create a new container cluster using GUI or gcloud, Slackdriver is automatically configured with a sink, however It did not work out of the box for me hence this post :)
Well, the easiest way to check if Slackdriver is configured is to issue a command