Kubernetes - Azure - remove annoying message 'enter your password for the ssh key'

Trying Kubernets on Azure has been a very painful experience, especially because I were unable to start both the examples presented in the documentation.

I discovered they are bugged, in this post I explain how to overcome the bug present in the first one.

https://github.com/kubernetes/kubernetes/blob/master/docs/getting-started-guides/coreos/azure/README.md

https://github.com/kubernetes/kubernetes/blob/master/docs/getting-started-guides/azure.md

After have successfully executed the create-kubernetes-cluster.js I was unable to follow the guide because every time I try to connect via ssh I was prompted by an annoying message:  "Enter your password for the SSH key"

after a long search I figured out the problem.
The easiest way to avoid this popup is patch the SSH key using the command:

openssl rsa -in ./output/kube_7c84ff0d2685e5_ssh.key -out ./output/kube_7c84ff0d2685e5_ssh.key

finally you can execute:

ssh -F  ./output/kube_7c84ff0d2685e5_ssh_conf kube-00

and continue with the guide.