network-mapper VS CoreDNS

Yep! When you deploy Otterize, you get a map of your cluster’s traffic, with zero-configuration, through the open-source network-mapper.

After multiple iterations, research sessions and some trial & error, we could produce an exportable list of network connections in any Kubernetes cluster. You might recall that our larger goal was to get to a logical (functional) map of pod-to-pod traffic, and that will be covered in a future posting. After adding that capability, here’s an example output from our project, now called network-mapper, when pointed at one of the clusters in our “lab” environment:

It'll require some changes but you can go for it if that's something up your alley, as after all, it's all open source - https://github.com/otterize/network-mapper

We received some great feedback from the community regarding our tool, and one of the most commonly requested features was visualization. So we embedded this functionality into the tool, and now you can easily map and visualize your cluster with a single CLI command.

As you've mentioned, it is not possible to define deny rules using the native NetworkPolicy resource. Instead, you could use your CNI’s implementation for network policies. If you use Calico as your CNI you can use Calico's network policies to create deny rules. You can also take a look at Otterize OSS, an open-source solution my team and I are working on recently. It simplifies network policies by defining them from the client’s perspective in a ClientIntents resource. You can use the network mapper to auto-generate those ClientIntents from the traffic in your cluster, and then deploy them and let the intents-operator manage the network policies for you.

CoreDNS supports this via the bind plugin.

I'd like to use Cloudflare's 1.1.1.1 and 1.0.0.1 nameservers in Kubernetes, alongside DNS over TLS. It looks like I can do it using core-dns. I need to setup the following somehow:

Shamless plug for CoreDNS. Much better DNS server than classic bind9. And of course there's already a nice container image for it.

But another approach that could work in Kubernetes, because the DNS servers are within the cluster itself, would be to work directly with the DNS server pods. In most Kubernetes clusters, whether standalone or managed (GKE, AKS, EKS), the cluster DNS is either coredns or kube-dns. That was great to minimize how much configuration options we’d need to support. We realized we could edit the coredns or kube-dns configmap resources to enable their log option, which would make them log all the queries they handle. We’ll cover exactly how it’s done in more detail below.

CoreDNS has an ectd plugin, so your service could add entries to a database, which is used as record source. Not the same mechanism as you have described, but it will get the job done. Also this is what Kubetnetes does for incluster dns records.

nevermind there's caddy builtin upgrade method https://github.com/coredns/coredns/issues/6034

Coredns can be spun up in a docker container, just starting to get into it myself

CoreDNS is a pretty good DNS server.

Core DNS (https://coredns.io).