Securing internal service communication in a Kubernetes cluster with https and TLS

Question

I'm working on a set of microservices and I need to secure the communication between the individual services (using https + TLS)

The service deployments have a Service object set up with an assigned Cluster IP. kube-dns automatically creates a DNS record with format *.cluster.local when the services are created. The problem is that I'm not allowed to create TLS certificates with a SN containing "local" in my org. So any certificate that I create for the services would end up failing certificate validation because the SN doesn't match the domain name. What I would like to do is to add a CNAME to kube-dns with my own custom domain name (ie servicename.cluster-internal.com) that would return the *.cluster.local domain, which would then resolve to the correct ClusterIP. I would create the certificates with the SN set to my custom domains so that certificate validation would not fail when the services try to handshake and set up a secure connection.

I'm open to other ways of doing this, but I would prefer not to take dependencies on other types of DNS providers or to have to write my own.

Answer 1

Before we solved the issue the correct way, we disabled certificate validation in the services that were running in the cluster. I don't recommend this approach, but it's an easier way to unblock.

We solved this the correct way by customizing our DNS. Since we deploy clusters with ACS-Engine, it was only a matter of redeploying our clusters with some updated options in the cluster definition .

See below:

"kubernetesConfig": {
"kubeletConfig": {
    "--cluster-domain": "domain.you.own"
  }
}

This gave us the ability to cut certs in "domain.you.own" and turn certificate validation back on.