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In this workshop we will create your own namespace, deployment and service. We will also destroy a pod, get more info on services and update our pods to a newer version.

Before we start, check the kubectl cheat sheet. We will use this utility during the workshop. https://files.acrobat.com/a/preview/5f7379e6-8331-4b90-ac64-691190c06ad3

Go to this link: https://cloud.google.com/shell/

Launch the cloud shell. Use your Devoteam account to login. When the shell appear copy below, paste it there and hit enter.

gcloud beta container clusters get-credentials standard-cluster-1 --region europe-west4 --project docker-training-207312

Now that we are into the cluster we need to create a namespace, but first let's see what namespaces are there already.

kubectl get namespace

NAME          STATUS    AGE
default       Active    1d
kube-system   Active    1d
kube-public   Active    1d

You probably see something similiar above. Those are the default namespaces that are always there. If you will not specify a namespace, all your deployments and changes will be done on the default namespace.  

It's now time to create your own namespace. Use the command below and change the name in the example to your own name.

kubectl create namespace wesley-rouw

Most commands are easy to use in Kubernetes, switching between namespaces is a different story. Copy the command and you will be in your namespace. Every work you will do, will now be done in this namespace. Work that will be done by others will be done in their own namespace.

kubectl config set-context $(kubectl config current-context) --namespace=wesley-rouw

Now that we are in the right namespace we will deploy our replicaset

kubectl apply -f https://raw.githubusercontent.com/Wesbest/KubernetesForEveryone/master/Training/kubernetes_deployment1.yaml

We have just deployed the following. It's a deployment with 3 pods.

apiVersion: apps/v1
kind: Deployment
metadata:
  name: kubern8sdemo
  labels:
    app: kubern8sdemo
spec:
  replicas: 3
  selector:
    matchLabels:
      app: kubern8sdemo
  template:
    metadata:
      labels:
        app: kubern8sdemo
    spec:
      containers:
      - name: kubern8sdemo
        image: mvdmeij/k8sdemo:v1
        ports:
        - containerPort: 80

To make sure if the deployment went correctly we are going to check the status

kubectl get deployments

You should see something similar like this. These are the amounts of pods you have created during this deployment. As you can see you have a desired amount of 3 pods and the current amount of pods are 3

NAME           DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE
kubern8sdemo   3         3         3            3           43s

Let's now take a closer look at the pods.

kubectl get pods

NAME                           READY     STATUS    RESTARTS   AGE
kubern8sdemo-68fcf74b6-55vjr   1/1       Running   0          1m
kubern8sdemo-68fcf74b6-h8ncl   1/1       Running   0          1m
kubern8sdemo-68fcf74b6-qddsp   1/1       Running   0          1m

As you can see there are three pods created each running with an own name. What would happen if we would delete one pod? Use the command below and change the name of the pod to yours.

kubectl delete pod kubern8sdemo-68fcf74b6-55vjr

Okay we have now deleted the pod. Let's take a look at the status of the pods

kubectl get pods

NAME                           READY     STATUS    RESTARTS   AGE
kubern8sdemo-68fcf74b6-h8ncl   1/1       Running   0          2m
kubern8sdemo-68fcf74b6-qddsp   1/1       Running   0          2m
kubern8sdemo-68fcf74b6-s4j2h   1/1       Running   0          24s

In my example you can see there are still three pods running, how is that possible? We have deleted a pod, but we have stated that the desired amount of the pods should be 3. Kubernetes have automatically created a new pod. Above you can see a new pod has been created 24s ago while the other 2 were created 2m ago.  

So how do we reduce the amounts of pods then? We will have to scale the replicaset. We are going to scale down the deployment to 2 pods. This will be a permanent change, unless we late adjust the desired amount again.

kubectl scale deployments kubern8sdemo --replicas=2  

Now let's check the amount of pods

kubectl get pods

NAME                           READY     STATUS    RESTARTS   AGE
kubern8sdemo-68fcf74b6-h8ncl   1/1       Running   0          7m
kubern8sdemo-68fcf74b6-qddsp   1/1       Running   0          7m

As you can see the amount of pods has been reduced. Let's check the deployment to see the desired amount of pods

kubectl get deployments

NAME           DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE
kubern8sdemo   2         2         2            2           10m

The desired amount is now 2.

We have our application ready, let's expose it to the outside world. For that we need to create a loadbalancer. This loadbalancer will be linked to the deployment with the use of the selectors and labels. Create the service:

Download the service:

wget https://raw.githubusercontent.com/Wesbest/KubernetesForEveryone/master/Training/kubernetes_service1.yaml

First we need to manipulate the service defintion by adding an external ip adress. Select ip that is available in the following link: https://bit.ly/2GuBdRf

Add the external ip adress by replacing the CHANGE_ME with the ip adresses that you have selected from the list. First add this comment to a notepad and add the ip as described below. When you copy the command and paste it to the cloud shell it automatically hits enter before you have even edited the ip address.

sed -i 's/IP_ADDRESS/CHANGE_ME/g' kubernetes_service1.yaml
eg:  
sed -i 's/IP_ADDRESS/10.10.10.1/g' kubernetes_service1.yaml

Let's apply the service:

kubectl create -f kubernetes_service1.yaml

To get a clear view of what we have created I have included the yaml file of the service.

apiVersion: v1
kind: Service
metadata:
  name: kubern8sservice
  labels:
    app: kubern8sdemo
spec:
  ports:  
  - port: 80
    targetPort: 80
  selector:
    app: kubern8sdemo
  type: LoadBalancer

To check the status of the service, use the command below.

kubectl get service

NAME              TYPE           CLUSTER-IP      EXTERNAL-IP     PORT(S)        AGE
kubern8sservice   LoadBalancer   10.51.240.199   35.242.185.86   80:32015/TCP   47s

Something similar should appear. The loadbalancer is now created and has got an external ip. If it says pending, just wait a little longer it should appear soon.  

We have connected the service to the pods with the labels and selectors. When we will check our browser we will see the application. Open a new tab and copy the external IP. A webapplication should appear. Hit the autorefresh button. We will need that later.

Don't you think our application is outdated? I've heard the image got some updates, let's check it out. Remember the deployment?

apiVersion: apps/v1
kind: Deployment
metadata:
  name: kubern8sdemo
  labels:
    app: kubern8sdemo
spec:
  replicas: 3
  selector:
    matchLabels:
      app: kubern8sdemo
  template:
    metadata:
      labels:
        app: kubern8sdemo
    spec:
      containers:
      - name: kubern8sdemo
        image: mvdmeij/k8sdemo:v1
        ports:
        - containerPort: 80

As you can see it has version 1. Currently they are already on version 5. With a single command we can update the the pods. When you do so, don't forget to check your browser. Before proceeding to the next steps, wait till the application has been updated in your browser.

kubectl set image deployment/kubern8sdemo kubern8sdemo=mvdmeij/k8sdemo:v5

I think version 5 is a little bit too overwhelming, we will switch to an older version. When we have done so, we will check out the status of the pods to see what happens under the hood when we do a rollout of an older or newer version to the pods.

kubectl set image deployment/kubern8sdemo kubern8sdemo=mvdmeij/k8sdemo:v3

kubectl get pods -w

the -w means that we are watching for changes. when you have executed that command you should see something similar like this:

NAME                           READY     STATUS              RESTARTS   AGE
kubern8sdemo-7b4db456b-j59sd   1/1       Running             0          2m
kubern8sdemo-7b4db456b-npk75   1/1       Running             0          2m
kubern8sdemo-84ff7fd64-w4ksc   0/1       ContainerCreating   0          2s
kubern8sdemo-84ff7fd64-w4ksc   1/1       Running             0          3s
kubern8sdemo-7b4db456b-j59sd   1/1       Terminating         0          2m
kubern8sdemo-84ff7fd64-m4rzh   0/1       Pending             0          0s
kubern8sdemo-84ff7fd64-m4rzh   0/1       Pending             0          0s
kubern8sdemo-84ff7fd64-m4rzh   0/1       ContainerCreating   0          0s
kubern8sdemo-7b4db456b-j59sd   0/1       Terminating         0          2m
kubern8sdemo-7b4db456b-j59sd   0/1       Terminating         0          2m
kubern8sdemo-7b4db456b-j59sd   0/1       Terminating         0          2m
kubern8sdemo-84ff7fd64-m4rzh   1/1       Running             0          4s
kubern8sdemo-7b4db456b-npk75   1/1       Terminating         0          2m
kubern8sdemo-7b4db456b-npk75   0/1       Terminating         0          2m
kubern8sdemo-7b4db456b-npk75   0/1       Terminating         0          2m
kubern8sdemo-7b4db456b-npk75   0/1       Terminating         0          2m

Kubernetes is creating a new container and then terminates one and does this one more time since our desired amount is 2 containers. Use control/cmd c to stop it.

Well that's about it. You have learnt how to set up your own namespace. In this namespace you have set up a pod with 3 containers. Later we have scaled this amount down to 2. After that you have set up your own loadbalancer. Kubernetes automatically detected to which pod it needs to be connected. At last we have updated the version of the images the containers were running. In case you have questions, please feel free to ask.