Creating a local cluster

One of the strengths of Kubernetes as a deployment platform is that you can create a local cluster and, with relatively little effort, have a realistic environment that is very close to your production environment. The main benefit is that developers can test their microservices locally and collaborate with the rest of the services in the cluster. When your system is comprised of many microservices, the more significant tests are often integration tests and even configuration and infrastructure tests, as opposed to unit tests. Kubernetes makes that kind of testing much easier and requires much less brittle mocking.

In this section, you will install a local Kubernetes cluster and some additional projects, and then have some fun exploring it using the invaluable kubectl command-line tool.

Installing Minikube

Minikube is a single node Kubernetes cluster that you can install anywhere. I used macOS here, but, in the past, I used it successfully on Windows too. Before installing Minikube itself, you must install a hypervisor. I prefer HyperKit:

$ curl -LO https://storage.googleapis.com/minikube/releases/latest/docker-machine-driver-hyperkit \
  && chmod +x docker-machine-driver-hyperkit \
  && sudo mv docker-machine-driver-hyperkit /usr/local/bin/ \
  && sudo chown root:wheel /usr/local/bin/docker-machine-driver-hyperkit \
  && sudo chmod u+s /usr/local/bin/docker-machine-driver-hyperkit

But, I've run into trouble with HyperKit from time to time. If you can't overcome the issues, I suggest using VirtualBox as the hypervisor instead. Run the following command to install VirtualBox via Homebrew:

$ brew cask install virtualbox

Now, you can install Minikube itself. Homebrew is the best way to go again:

brew cask install minikube

If you're not on macOS, follow the official instructions here: https://kubernetes.io/docs/tasks/tools/install-minikube/.

You must turn off any VPN before starting Minikube with HyperKit. You can restart your VPN after Minikube has started.

Minikube supports multiple versions of Kubernetes. At the moment, the default version is 1.10.0, but 1.13.0 is already out and supported, so let's use that version:

$ minikube start --vm-driver=hyperkit --kubernetes-version=v1.13.0

If you're using VirtualBox as your hypervisor, you don't need to specify --vm-driver:

$ minikube start --kubernetes-version=v1.13.0

You should see the following:

$ minikube start --kubernetes-version=v1.13.0
Starting local Kubernetes v1.13.0 cluster...
Starting VM...
Downloading Minikube ISO
 178.88 MB / 178.88 MB [============================================] 100.00% 0s
Getting VM IP address...
E0111 07:47:46.013804   18969 start.go:211] Error parsing version semver:  Version string empty
Moving files into cluster...
Downloading kubeadm v1.13.0
Downloading kubelet v1.13.0
Finished Downloading kubeadm v1.13.0
Finished Downloading kubelet v1.13.0
Setting up certs...
Connecting to cluster...
Setting up kubeconfig...
Stopping extra container runtimes...
Starting cluster components...
Verifying kubelet health ...
Verifying apiserver health ...Kubectl is now configured to use the cluster.
Loading cached images from config file.


Everything looks great. Please enjoy minikube!

Minikube will automatically download the Minikube VM (178.88 MB) if it's the first time you are starting your Minikube cluster.

At this point, your Minikube cluster is ready to go.

Troubleshooting Minikube

If you run into some trouble (for example, if you forgot to turn off your VPN), try to delete your Minikube installation and restart it with verbose logging:

$ minikube delete
$ rm -rf ~/.minikube
$ minikube start --vm-driver=hyperkit --kubernetes-version=v1.13.0 --logtostderr --v=3

If your Minikube installation just hangs (maybe waiting for SSH), you might have to reboot to unstick it. If that doesn't help, try the following:

sudo mv /var/db/dhcpd_leases /var/db/dhcpd_leases.old
sudo touch /var/db/dhcpd_leases

Then, reboot again.

Verifying your cluster

If everything is OK, you can check your Minikube version:

$ minikube version
minikube version: v0.31.0

Minikube has many other useful commands. Just type minikube to see the list of commands and flags.

Playing with your cluster

Minikube is running, so let's have some fun. Your kubectl is going to serve you well in this section. Let's start by examining our node:

$ kubectl get nodes
NAME       STATUS    ROLES     AGE       VERSION
minikube   Ready     master    4m        v1.13.0

Your cluster already has some pods and services running. It turns out that Kubernetes is dogfooding and many of its own services are plain services and pods. But, those pods and services run in namespaces. Here are all the namespaces:

$ kubectl get ns
NAME          STATUS    AGE
default       Active    18m
kube-public   Active    18m
kube-system   Active    18m

To see all the services in all the namespaces, you can use the --all-namespaces flag:

$ kubectl get svc --all-namespaces
NAMESPACE          NAME  TYPE   CLUSTER-IP  EXTERNAL-IP   PORT(S)   AGE
default  kubernetes   ClusterIP   10.96.0.1  <none>   443/TCP       19m
kube-system kube-dns  ClusterIP   10.96.0.10 <none>   53/UDP,53/TCP 19m
kube-system kubernetes-dashboard  ClusterIP 10.111.39.46 <none>        80/TCP          18m

The Kubernetes API server, itself, is running as a service in the default namespace and then we have kube-dns and the kubernetes-dashboard running in the kube-system namespace.

To explore the dashboard, you can run the dedicated Minikube command, minikube dashboard. You can also use kubectl, which is more universal and will work on any Kubernetes cluster:

$ kubectl port-forward deployment/kubernetes-dashboard 9090

Then, browse to http://localhost:9090 and you will see the following dashboard:

Installing Helm

Helm is the Kubernetes package manager. It doesn't come with Kubernetes, so you have to install it. Helm has two components: a server-side component called tiller, and a CLI called helm.

Let's install helm locally first, using Homebrew:

$ brew install kubernetes-helm

Then, properly initialize both the server and client type:

$ helm init
$HELM_HOME has been configured at /Users/gigi.sayfan/.helm.

Tiller (the Helm server-side component) has been installed into your Kubernetes Cluster.

Please note: by default, Tiller is deployed with an insecure 'allow unauthenticated users' policy.
To prevent this, run `helm init` with the --tiller-tls-verify flag.
For more information on securing your installation see: https://docs.helm.sh/using_helm/#securing-your-helm-installation
Happy Helming!

With Helm in place, you can easily install all kinds of goodies in your Kubernetes cluster. There are currently 275 chars (the Helm term for a package) in the stable chart repository:

$ helm search | wc -l
275

For example, check out all the releases tagged with the db type:

$ helm search db
NAME                               CHART VERSION  APP VERSION    DESCRIPTION
stable/cockroachdb                 2.0.6          2.1.1          CockroachDB is a scalable, survivable, strongly-consisten...
stable/hlf-couchdb                 1.0.5          0.4.9          CouchDB instance for Hyperledger Fabric (these charts are...
stable/influxdb                    1.0.0          1.7            Scalable datastore for metrics, events, and real-time ana...
stable/kubedb                      0.1.3          0.8.0-beta.2   DEPRECATED KubeDB by AppsCode - Making running production...
stable/mariadb                     5.2.3          10.1.37        Fast, reliable, scalable, and easy to use open-source rel...
stable/mongodb                     4.9.1          4.0.3          NoSQL document-oriented database that stores JSON-like do...
stable/mongodb-replicaset          3.8.0          3.6            NoSQL document-oriented database that stores JSON-like do...
stable/percona-xtradb-cluster      0.6.0          5.7.19         free, fully compatible, enhanced, open source drop-in rep...
stable/prometheus-couchdb-exporter 0.1.0          1.0            A Helm chart to export the metrics from couchdb in Promet...
stable/rethinkdb                   0.2.0          0.1.0          The open-source database for the realtime web
jenkins-x/cb-app-slack             0.0.1                         A Slack App for CloudBees Core
stable/kapacitor                   1.1.0          1.5.1          InfluxDB's native data processing engine. It can process ...
stable/lamp                        0.1.5          5.7            Modular and transparent LAMP stack chart supporting PHP-F...
stable/postgresql                  2.7.6          10.6.0         Chart for PostgreSQL, an object-relational database manag...
stable/phpmyadmin                  2.0.0          4.8.3          phpMyAdmin is an mysql administration frontend
stable/unifi                       0.2.1          5.9.29         Ubiquiti Network's Unifi Controller

We will use Helm a lot throughout the book.