Now we will deploy Jenkins-Docker on local Kubernetes. If you haven’t Kubernetes running yet, feel free to have a look on my previous tutorial. I will try to describe with very basic steps the tutorial. That’s may confusing for advanced peoples or experts but it should help beginner to get in that topic. For example, this tutorial uses 2 YAML files.

Preparation

# create new project
$ mkdir -p ~/Projects/KubernetesJenkins && cd ~/Projects/KubernetesJenkins

# create needed files
$ touch namespace.yml pod.yml

# modify namespace.yml
$ vim namespace.yml

# modify pod.yml
$ vim pod.yml

apiVersion: v1
kind: Namespace
metadata:
  name: qa-namespace
  labels:
    name: qa-namespace

apiVersion: v1
kind: Pod
metadata:
  name: jenkins.example.com
  labels:
    app: qa-jenkins-app
  namespace: qa-namespace
spec:
  containers:
    - name: jenkins
      image: jenkins/jenkins:lts-alpine
      ports:
        - containerPort: 8080

Let’s go – start Jenkins container on Kubernetes

# show nodes (optional)
$ kubectl get nodes

# create namespace
$ kubectl create -f ~/Projects/KubernetesJenkins/namespace.yml

# show namespaces (optional)
$ kubectl get namespaces --show-labels

# create pod
$ kubectl create -f pod.yml

# show pods of namespace
$ kubectl get pods --namespace qa-namespace

# show pod informations (optional)
$ kubectl describe pod jenkins.example.com --namespace qa-namespace

Open Jenkins in Browser

Jenkins is already running but you cannot access Jenkins without one important step! You need to configure the network routing. Probably the easiest option to do that is a simple port-forward.

# show ports in use (optional)
$ lsof -i -P | grep -i "listen"

# create port-forward to specific namespace
$ kubectl port-forward jenkins.example.com 8080:8080 --namespace=qa-namespace

# open browser (new terminal)
$ open http://localhost:8080

The 2nd way is to expose a service. This possibility is recommended only for local environments! For example on AWS you use load-balancer and there the way is a little bit different.

# expose pod as service
$ kubectl expose pod jenkins.example.com --namespace=qa-namespace --type=NodePort --name jenkins-service

# show services in namespace (optional)
$ kubectl get services --namespace qa-namespace

# show service informations (optional)
$ kubectl get service jenkins-service --namespace qa-namespace

# get node port
$ kubectl describe service jenkins-service --namespace qa-namespace | grep NodePort

# open browser (same terminal)
$ open http://localhost:32654

Whatever way you prefer, you need the initial admin password for Jenkins and/or you may need to see logs.

# show key for Jenkins activation
$ kubectl exec jenkins.example.com --namespace qa-namespace -- cat /var/jenkins_home/secrets/initialAdminPassword

# show logs of pod
$ kubectl logs -f jenkins.example.com --namespace qa-namespace

That’s it… Now you can use Jenkins.

CleanUp

If you want to clean up, proceed as follows.

# delete service
$ kubectl delete service jenkins-service --namespace qa-namespace

# list services (optional)
$ kubectl get services --namespace qa-namespace

# delete pod
$ kubectl delete pod jenkins.example.com --force --namespace qa-namespace

# list pods (optional)
$ kubectl get pods --namespace qa-namespace

# delete namespace
$ kubectl delete namespaces qa-namespace

# list namespaces (optional)
$ kubectl get namespaces

The newer versions of Docker for Mac actually bring everything for the use of Kubernetes. Since the current documentation is not so optimal, I try it in my own way. Since I plan to further testing tutorials on this topic, this guide will serve as a basis.

Preparation

Kubernetes is currently only supported via Docker Edge. Caution, if you switch from stable to edge all Docker images and containers will be deleted! If you are already using the Edge version, skip the following steps 1 till 3.

1. Download Docker for Mac Edge Version… You can exit Docker for Mac while downloading.
2. After successful download of DMG start the installation (Replace the old version).
3. Start Docker and follow the instructions.
4. Activate Kubernetes now via “Enable Kubernetes” checkbox and install the Kubernetes cluster. This can take a while, do not lose your patience!
5. When the installation is finished you can check it.

Note, if you have already used minikube, you should now switch the cluster. You can switch between clusters at any time via GUI or command-line.

# show kubectl version
$ kubectl version
Client Version: version.Info{Major:"1", Minor:"9", GitVersion:"v1.9.6", GitCommit:"9f8ebd171479bec0ada837d7ee641dec2f8c6dd1", GitTreeState:"clean", BuildDate:"2018-03-21T15:21:50Z", GoVersion:"go1.9.3", Compiler:"gc", Platform:"darwin/amd64"}
Unable to connect to the server: dial tcp 192.168.99.100:8443: i/o timeout

# show current context
$ kubectl config current-context
minikube

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

# show kubectl version
$ kubectl version
Client Version: version.Info{Major:"1", Minor:"9", GitVersion:"v1.9.6", GitCommit:"9f8ebd171479bec0ada837d7ee641dec2f8c6dd1", GitTreeState:"clean", BuildDate:"2018-03-21T15:21:50Z", GoVersion:"go1.9.3", Compiler:"gc", Platform:"darwin/amd64"}
Server Version: version.Info{Major:"1", Minor:"9", GitVersion:"v1.9.6", GitCommit:"9f8ebd171479bec0ada837d7ee641dec2f8c6dd1", GitTreeState:"clean", BuildDate:"2018-03-21T15:13:31Z", GoVersion:"go1.9.3", Compiler:"gc", Platform:"linux/amd64"}

Now it’s a good time to know some more about current cluster, nodes, pods and namespaces. This will help to understand everything better!

# show cluster informations
$ 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:dns/proxy

To further debug and diagnose cluster problems, use 'kubectl cluster-info dump'.

# show nodes informations
$ kubectl get nodes
NAME                 STATUS    ROLES     AGE       VERSION
docker-for-desktop   Ready     master    14m       v1.9.6

# show pod informations
$ kubectl get pods
No resources found.

# show namespaces informations
$ kubectl get namespaces
NAME          STATUS    AGE
default       Active    23m
docker        Active    21m
kube-public   Active    23m
kube-system   Active    23m

As you can see, everything is working fine. The system is now ready for usage. By the way, have a look on your Docker images!

# list current Docker images (optional)
$ docker images
...

Deploying the Kubernetes Web UI Dashboard

Finally we deploy the Kubernetes Web UI Dashboard on our new Kubernetes Master as a Pod in namespace kube-system. The Dashboard is not installed/deployed by default. Although everything is possible via command-line, it can help to better understand and analyze the system.

# create a resource from a file
$ 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

# list pods in specific namespace
$ kubectl get pods --namespace=kube-system
NAME                                         READY     STATUS    RESTARTS   AGE
etcd-docker-for-desktop                      1/1       Running   0          46m
kube-apiserver-docker-for-desktop            1/1       Running   0          46m
kube-controller-manager-docker-for-desktop   1/1       Running   0          46m
kube-dns-6f4fd4bdf-f7pjw                     3/3       Running   0          47m
kube-proxy-c676q                             1/1       Running   0          47m
kube-scheduler-docker-for-desktop            1/1       Running   0          46m
kubernetes-dashboard-5bd6f767c7-f9w4j        1/1       Running   0          1m

# forward port to specific pod (Attention! Your pod may have a different name!)
$ kubectl port-forward kubernetes-dashboard-5bd6f767c7-f9w4j 8443:8443 --namespace=kube-system
Forwarding from 127.0.0.1:8443 -> 8443

# open Web UI Dashboard
$ open https://localhost:8443

You can skip authentication and jump directly to the dashboard. This step should may give you a hint. Never ever do the same in production!

That’s it already! Have a look on created dashboard and get familiar with your new Kubernetes environment.