At this point, there are cloud-based Kubernetes services in most public clouds that make it easy to create a cluster with a few command-line instructions.
This chapter covers installing Kubernetes on the three major cloud providers: the Google Cloud Platform, Microsoft Azure, and Amazon Web Services.
Once you have gcloud installed, set a default zone:
$ gcloud config set compute/zone us-west1-a
Then you can create a cluster:
$ gcloud container clusters create kuar-cluster --num-nodes=3`
This will take a few minutes. When the cluster is ready, you can get credentials for thecluster using:
$ gcloud container clusters get-credentials kuar-cluster`
When you have the shell up and working, you can run:
$ az group create --name=kuar --location=westus
Once the resource group is created, you can create a cluster using:
$ az aks create --resource-group=kuar --name=kuar-cluster
This will take a few minutes. Once the cluster is created, you can get credentials for the cluster with:
$ az aks get-credentials --resource-group=kuar --name=kuar-cluster
If you don’t already have the kubectl tool installed, you can install it using:
$ az aks install-cli
Amazon offers a managed Kubernetes service called Elastic Kubernetes Service(EKS). The easiest way to create an EKS cluster is via the open source eksctl command-line tool.
Once you have eksctl installed and in your path, you can run the following command to create a cluster:
$ eksctl create cluster
For more details on installation options (such as node size and more), view the help using this command:
$ eksctl create cluster --help
You can create a local cluster using:
$ minikube start
This will create a local VM, provision Kubernetes, and create a local kubectl configuration that points to that cluster. As mentioned previously, this cluster only has a single node, so while it is useful, it has some differences with most production deployments of Kubernetes.
When you are done with your cluster, you can stop the VM with:
$ minikube stop
The kind project provides a great experience for launching and managing test clusters in Docker. (kind stands for Kubernetes IN Docker.)
Once you get it installed, creating a cluster is as easy as:
$ kind create cluster --wait 5m
$ export KUBECONFIG="$(kind get kubeconfig-path)"
$ kubectl cluster-info
$ kind delete cluster
The official Kubernetes client is kubectl : a command-line tool for interacting with the Kubernetes API.
You can check the version of the cluster that you are running:
$ kubectl version
To verify that your cluster is generally healthy:
$ kubectl get componentstatuses
You can list all of the nodes in your cluster:
$ kubectl get nodes
In Kubernetes, nodes are separated into control-plane nodes that contain containers like the API server, scheduler, etc., which manage the cluster, and worker nodes where your containers will run. Kubernetes won’t generally schedule work onto control-plane nodes to ensure that user workloads don’t harm the overall operation of the cluster.
You can use the kubectl describe command to get more information about a specific node, such as kind-control-plane :
$ kubectl describe nodes kind-control-plane
One of the interesting aspects of Kubernetes is that many of the components that make up the Kubernetes cluster are actually deployed using Kubernetes itself.
The Kubernetes proxy is responsible for routing network traffic to load-balanced services in the Kubernetes cluster. Kubernetes has an API object named DaemonSet, which is used in many clusters to accomplish this.
$ kubectl get daemonSets --namespace=kube-system kube-proxy
Kubernetes also runs a DNS server, which provides naming and discovery for the services that are defined in the cluster. This DNS server also runs as a replicated service on the cluster. Depending on the size of your cluster, you may see one or more DNS servers running in your cluster. The DNS service is run as a Kubernetes deployment, which manages these replicas.
$ kubectl get deployments --namespace=kube-system coredns
There is also a Kubernetes service that performs load balancing for the DNS server:
$ kubectl get services --namespace=kube-system kube-dns
There is a community supported GUI for Kubernetes - documentation