Kind - Kubernetes in Docker

Work in progress…

From the documentation, “kind runs a local Kubernetes cluster by using Docker containers as ‘nodes’. kind uses the node-image to run Kubernetes artifacts, such as kubeadm or kubelet. The node-image in turn is built off the base-image, which installs all the dependencies needed for Docker and Kubernetes to run in a container.”

The release notes for the new version of kind say that “v0.6.0 brings major internal rework and some important breaking changes that we hope will make kind easier to use.”

Let’s find out.

Kind Installation

Download and use the latest version from the kind releases page. For example, starting from ubuntu with docker installed:

$ curl -Lo ./kind https://github.com/kubernetes-sigs/kind/releases/download/v0.6.0/kind-linux-amd64
$ chmod +x ./kind
$ ./kind create cluster
Creating cluster "kind" ...
 ✓ Ensuring node image (kindest/node:v1.16.3) 🖼 
 ✓ Preparing nodes 📦 
 ✓ Writing configuration 📜 
 ✓ Starting control-plane 🕹️ 
 ✓ Installing CNI 🔌 
 ✓ Installing StorageClass 💾 
Set kubectl context to "kind-kind"
You can now use your cluster with:

kubectl cluster-info --context kind-kind

And the local cluster is ready to use, having downloaded the following image:

$ docker images
REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
kindest/node        v1.16.3             066d19ae6707        2 weeks ago         1.22GB

As the name “kubernetes in docker” suggests, the nodes run as local docker containers. In that way it’s similar to minikube’s –vm-driver=none option that runs the Kubernetes components on the host and not in a VM

$ docker ps
CONTAINER ID        IMAGE                  COMMAND                  CREATED             STATUS              PORTS                       NAMES
a510f4f640f2        kindest/node:v1.16.3   "/usr/local/bin/entr…"   8 minutes ago       Up 8 minutes        127.0.0.1:36341->6443/tcp   kind-control-plane

Using Kind

Unlike microk8s, kind (by design) doesn’t include kubectl, and without it, the cluster won’t be doing much. Install kubectl via your preferred method. Perhaps:

$ sudo snap install kubectl --classic
kubectl 1.16.3 from Canonical✓ installed

Now you can see what’s been created for you:

$ kubectl get all --all-namespaces
NAMESPACE     NAME                           READY   STATUS    RESTARTS   AGE
kube-system   pod/coredns-5644d7b6d9-2bb5r   1/1     Running   0          39s
kube-system   pod/coredns-5644d7b6d9-np2kn   1/1     Running   0          39s
kube-system   pod/kindnet-jvhxk              1/1     Running   0          39s
kube-system   pod/kube-proxy-8znjp           1/1     Running   0          39s

NAMESPACE     NAME                 TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)                  AGE
default       service/kubernetes   ClusterIP   10.96.0.1    <none>        443/TCP                  55s
kube-system   service/kube-dns     ClusterIP   10.96.0.10   <none>        53/UDP,53/TCP,9153/TCP   53s

NAMESPACE     NAME                        DESIRED   CURRENT   READY   UP-TO-DATE   AVAILABLE   NODE SELECTOR                 AGE
kube-system   daemonset.apps/kindnet      1         1         1       1            1           <none>                        52s
kube-system   daemonset.apps/kube-proxy   1         1         1       1            1           beta.kubernetes.io/os=linux   53s

NAMESPACE     NAME                      READY   UP-TO-DATE   AVAILABLE   AGE
kube-system   deployment.apps/coredns   2/2     2            2           53s

NAMESPACE     NAME                                 DESIRED   CURRENT   READY   AGE
kube-system   replicaset.apps/coredns-5644d7b6d9   2         2         2       39s

And from there you can use the local cluster any way you wish.

kubectl apply -f https://example.com/random_code_from_the_internet.yaml

I’ll add a nice minimal example here soon - once I find one. I don’t want to push node images to your machine.

The Only Failing

Calling the tool kind makes it immune to googling. The Go language almost resolves that problem by masquerading as golang. I guess that by the time kind makes it into central packages it may be going by a different name. Hopefully kindergarten.

So there’s probably no future for man kind.