CoreDNS VS cni

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).

The CNI is language-agnostic and there are many different plugins available.

Read more about the architecture of CRI-O here. The networking of the pod is set up through CNI, and CRI-O can be used with any CNI plugin.

In generic Kubernetes network policies, there is no action field. The Calico CNI plugin (Kubernetes network plugin that implements the Container Network Interface) provides this functionality, and in particular provides logging even for allowed traffic. And this worked when we tried it in our test clusters and in our own back end.

There is a CNI spec: https://github.com/containernetworking/cni/blob/main/SPEC.md which allows for custom network plugins. Thats how AWS/EKS nodes are able to assign VPC routable IPs to containers running on them.

um, they aren't missing anything (but see below). they are k8s.

so if you want to get the genuine original mainline experience you go to the project's github repo, they have releases, and mention that the detailed changelog has links to the binaries. yeey. (https://github.com/kubernetes/kubernetes/blob/master/CHANGEL... .. the client is the kubectl binary, the server has the control plane components the node binaries have the worker node stuff), you then have the option to set those up according to the documentation (generate TLS certs, specify the IP address range for pods (containers), install dependencies like etcd, and a CNI compatible container network layer provider -- if you have setup overlay networking eg. VXLAN or geneve or something fancy with openvswitch's OVN -- then the reference CNI plugin is probably sufficient)

at the end of this process you'll have the REST API (kube-apiserver) up and running and you can start submitting jobs (that will be persisted into etcd, eventually picked up by the scheduler control loop that calculates what should run where and persists it back to etcd, then a control loop on a particular worker will notice that something new is assigned to it, and it'll do the thing, allocate a pod, call CNI to allocate IP, etc.)

of course if you don't want to do all this by hand you can use a distribution that helps you with setup.

microk8s is a low-memory low-IO k8s distro by Canonical (Ubuntu folks) and they run dqlite (distributed sqlite) instead of etcd (to lower I/O and memory requirements), many people don't like it because it uses snaps

k3s is started by Rancher folks (and mostly still developed by them?),

there's k0s (for bare metal ... I have no idea what that means though), kind (kubernetes in docker), there's also k3d (k3s in docker)

these distributions work by consuming/wrapping the k8s components as go libraries - https://github.com/kubernetes/kubernetes/blob/master/staging...

...

then there's the whole zoo of various k8s plugins/addons/tools for networking (CNI - https://github.com/containernetworking/cni#3rd-party-plugins), storage (CSI - https://kubernetes-csi.github.io/docs/drivers.html), helm for package management, a ton of security-related things that try to spot errors in all this circus ... and so on.

#! /usr/bin/bash # Update apt-get repository and install dependencies apt-get update && apt-get install -y --no-install-recommends dmsetup openssh-client git binutils # Install containerd if it's not present -- prevents breaking docker-ce installations which containerd || apt-get install -y --no-install-recommends containerd # Installing CNI # Current version from https://github.com/containernetworking/cni/releases export CNI_VERSION=v1.0.1 ARCH=$([ "$(uname -m)" = "x86_64" ] && echo amd64 || echo arm64) export ARCH sudo mkdir -p /opt/cni/bin curl -sSL "https://github.com/containernetworking/plugins/releases/download/${CNI_VERSION}/cni-plugins-linux-${ARCH}-${CNI_VERSION}.tgz" | sudo tar -xz -C /opt/cni/bin # Installing Ignite # Get the current version from https://github.com/weaveworks/ignite/releases export VERSION=v0.10.0 GOARCH=$(go env GOARCH 2>/dev/null || echo "amd64") export GOARCH for binary in ignite ignited; do echo "Installing ${binary}..." curl -sfLo ${binary} "https://github.com/weaveworks/ignite/releases/download/${VERSION}/${binary}-${GOARCH}" chmod +x ${binary} sudo mv ${binary} /usr/local/bin done # Check if the installation was successful ignite version

The Container Network Interface (CNI) includes a specification for writing network plugins to configure network interfaces. This allows you to create overlay networks that satisfy Pod-to-Pod communication requirements.

In this lab you will bootstrap three Kubernetes worker nodes. The following components will be installed on each node: runc, container networking plugins, containerd, kubelet, and kube-proxy.

CNI type plugins follow the Container Network Interface spec and are used by the community to create advanced featured plugins. On the other hand, Kubenet utilizes bridge and host-local CNI plugins and has basic features.