Tutorial : Getting Started with Kubernetes with Docker on Mac

This is not with Minikube, which you can still install on a Mac. It is with a Edge version of Docker on Mac.

This tutorial works on the Edge version of Docker on Mac and could undergo changes as it approaches a stable release. I will keep the article updated.

We shall cover the following in this post:

• Installing Docker on Mac Edge version
• Go through the basic Kubernetes commands to validate our environment.

It is important that you go through some basic material on its concepts, so that we can directly get down into its commands.

As per the official documentation, Kubernetes is only available in Docker for Mac 17.12 CE Edge. Go to the official download page and click on the Edge channel and not the Stable version.

Download the .dmg file and go ahead with the standard installation steps. You can then launch Docker Edge. Click on the Docker icon and go to Preferences window as shown below. Click on the Kubernetes icon.

You will notice that Kubernetes is not enabled. Simply check on the Enable Kubernetes option and then hit the Apply button as shown below:

This will display a message that the Kubernetes cluster needs to be installed. Make sure you are connected to the Internet and click on Install

The installation starts. Please be patient since this could take a while depending on your network. It would have been nice to see a small log window that shows a sequence of steps.

Finally, you should see the following message:

Click on Close. This will lead you back to the Preferences dialog and you should see the following screen:

Note the two messages at the bottom of the window mentioning:

• Docker is running
• Kubernetes is running

In case you stop running and try to run Docker again, you will notice that both Docker and Kubernetes services are starting as shown below:

Congratulations! You now have the following:

• A standalone Kubernetes server and client, as well as Docker CLI integration.
• The Kubernetes server is a single-node cluster and is not configurable.

Just FYI … my About Docker shows the following:

Let us try out a few things to ensure that we can make sense of what has got installed. Execute the following commands in a terminal:

$ kubectl version
Client Version: version.Info{Major:”1", Minor:”8", GitVersion:”v1.8.4", GitCommit:”9befc2b8928a9426501d3bf62f72849d5cbcd5a3", GitTreeState:”clean”, BuildDate:”2017–11–20T05:28:34Z”, GoVersion:”go1.8.3", Compiler:”gc”, Platform:”darwin/amd64"}
Server Version: version.Info{Major:”1", Minor:”8", GitVersion:”v1.8.2", GitCommit:”bdaeafa71f6c7c04636251031f93464384d54963", GitTreeState:”clean”, BuildDate:”2017–10–24T19:38:10Z”, GoVersion:”go1.8.3", Compiler:”gc”, Platform:”linux/amd64"}

You might have noticed that my server and client versions are different. I am using kubectl from my gCloud SDK tools and Docker for Mac, when it launched the Kubernetes cluster has been able to set the cluster context for the kubectl utility for you. So if we fire the following command:

$ kubectl config current-context
docker-for-desktop

You can see that the cluster is set to docker-for-desktop.

Tip: In case you switch between different clusters, you can always get back using the following:

$ kubectl config use-context docker-for-desktop
Switched to context "docker-for-desktop"

Let us get some information on the cluster.

$ kubectl cluster-info
Kubernetes master is running at https://localhost:6443
KubeDNS is running at https://localhost:6443/api/v1/namespaces/kube-system/services/kube-dns/proxy

Let us check out the nodes in the cluster:

$ kubectl get nodes
NAME STATUS ROLES AGE VERSION
docker-for-desktop Ready master 7h v1.8.2

The next step that we need to do here is to install the Kubernetes Dashboard. We can use the Kubernetes Dashboard YAML that is available and submit the same to the Kubernetes Master as follows:

$ kubectl create -f https://raw.githubusercontent.com/kubernetes/dashboard/master/src/deploy/recommended/kubernetes-dashboard.yaml
secret “kubernetes-dashboard-certs” created
serviceaccount “kubernetes-dashboard” created
role “kubernetes-dashboard-minimal” created
rolebinding “kubernetes-dashboard-minimal” created
deployment “kubernetes-dashboard” created
service “kubernetes-dashboard” created

The Dashboard application will get deployed as a Pod in the kube-system namespace. We can get a list of all our Pods in that namespace via the following command:

$ kubectl get pods --namespace kube-system
NAME READY STATUS RESTARTS AGE
etcd-docker-for-desktop 1/1 Running 0 8h
kube-apiserver-docker-for-desktop 1/1 Running 0 7h
kube-controller-manager-docker-for-desktop 1/1 Running 0 8h
kube-dns-545bc4bfd4-l9tw9 3/3 Running 0 8h
kube-proxy-w8pq7 1/1 Running 0 8h
kube-scheduler-docker-for-desktop 1/1 Running 0 7h
kubernetes-dashboard-7798c48646-ctrtl  1/1 Running 0 3m

Ensure that the Pod shown in bold is in Running state. It could take some time to change from ContainerCreating to Running, so be patient.

Once it is in running state, you can setup a forwarding port to that specific Pod. So in our case, we can setup 8443 for the Pod Name as shown below:

$ kubectl port-forward kubernetes-dashboard-7798c48646-ctrtl 8443:8443 --namespace kube-system
Forwarding from 127.0.0.1:8443 -> 8443

You can now launch a browser and go to https://localhost:8443. You might see some warnings but proceed. You will see the following screen:

Click on SKIP and you will be lead to the Dashboard as shown below:

Click on Nodes and you will see the single node as given below:

Let us proceed now to running a simple Nginx container to see the whole thing in action:

We are going to use the run command as shown below:

$ kubectl run hello-nginx --image=nginx --port=80
deployment “hello-nginx” created

This creates a deployment and we can investigate into the Pod that gets created, which will run the container:

$ kubectl get pods
NAME READY STATUS RESTARTS AGE
hello-nginx-5d47cdc4b7-wxf9b 0/1 ContainerCreating 0 16s

You can see that the STATUS column value is ContainerCreating.

Now, let us go back to the Dashboard and see the Deployments:

You can notice that if we go to the Deployments option, the Deployment is listed and the status is still in progress. You can also notice that the Pods value is 0/1.

If we wait for a while, the Pod will eventually get created and it will ready as the command below shows:

$ kubectl get pods
NAME READY STATUS RESTARTS AGE
hello-nginx-5d47cdc4b7-wxf9b 1/1 Running 0 3m

If we visit the Replica Sets now, we can see it:

Click on the Replica Set name and it will show the Pod details as given below:

Alternately, you can also get to the Pods via the Pods link in the Workloads as shown below:

Click on the Pod and you can get various details on it as given below:

You can see that it has been given some default labels. You can see its IP address. It is part of the node named docker-for-desktop.

There are some interesting links that you will find on this page as shown below, via which you can directly EXEC into the pods or see the logs too.

We could have got the Node and Pod details via a variety of kubectl describe node/pod commands and we can still do that. An example of that is shown below:

$ kubectl get pods
NAME READY STATUS RESTARTS AGE
hello-nginx-5d47cdc4b7-wxf9b 1/1 Running 0 10m
$ kubectl describe pod hello-nginx-5d47cdc4b7-wxf9b
Name: hello-nginx-5d47cdc4b7-wxf9b
Namespace: default
Node: docker-for-desktop/192.168.65.3
Start Time: Wed, 10 Jan 2018 18:10:35 +0530
Labels: pod-template-hash=1803787063
run=hello-nginx
Annotations: kubernetes.io/created-by={“kind”:”SerializedReference”,”apiVersion”:”v1",”reference”:{“kind”:”ReplicaSet”,”namespace”:”default”,”name”:”hello-nginx-5d47cdc4b7",”uid”:”7415cff7-f603–11e7–9f7b-025000000…
Status: Running
IP: 10.1.0.7
Created By: ReplicaSet/hello-nginx-5d47cdc4b7
Controlled By: ReplicaSet/hello-nginx-5d47cdc4b7
Containers:
hello-nginx:
Container ID: docker://a0c3309b61be4473bf6924ea2be9795de660f49bda36492785f94627690cbdae
Image: nginx
Image ID: docker-pullable://nginx@sha256:285b49d42c703fdf257d1e2422765c4ba9d3e37768d6ea83d7fe2043dad6e63d
Port: 80/TCP
State: Running
...// REST OF THE OUTPUT

It is time now to expose our basic Nginx deployment as a service. We can use the command shown below:

$ kubectl get deployments
NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE
hello-nginx 1 1 1 1 19m
$ kubectl expose deployment hello-nginx --type=NodePort
service “hello-nginx” exposed

If we visit the Dashboard at this point and go to the Services section, we can see out hello-nginx service entry.

Alternately, we can use kubectl too, to check it out:

$ kubectl get services
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
hello-nginx NodePort 10.107.132.220 <none> 80:30259/TCP 1m
kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 8h

and

$ kubectl describe service hello-nginx
Name: hello-nginx
Namespace: default
Labels: run=hello-nginx
Annotations: <none>
Selector: run=hello-nginx
Type: NodePort
IP: 10.107.132.220
Port: <unset> 80/TCP
TargetPort: 80/TCP
NodePort: <unset> 30259/TCP
Endpoints: 10.1.0.7:80
Session Affinity: None
External Traffic Policy: Cluster
Events: <none>

OK, I am not yet done!

When we created the deployment, we did not mention about the number of instances for our service. So we just had one Pod that was provisioned on the single node.

Let us go and see how we can scale this via the scale command. We want to scale it to 3 Pods.

$ kubectl scale --replicas=3 deployment/hello-nginx
deployment "hello-nginx" scaled

We can see the status of the deployment in a while:

$ kubectl get deployment
NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE
hello-nginx 3 3 3 3 45m

Now, if we visit the Dashboard for our Deployment:

We have the 3/3 Pods available. Similarly, we can see our Service or Pods.

Hope this blog post gets you started with Kubernetes with Docker for Mac. Please let me know about your experience in the comments. Now go forth and play the role of a helmsman.

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