Introduction to Kubernetes

Getting your OpenShift Sandbox account

Developer Sandbox for Red Hat OpenShift is a free Kubernetes cloud environment in a shared, multi-tenant OpenShift cluster that is pre-configured with a set of developer tools. The Developer Sandbox is active for 30 days and renewable once it expires.

To create your account, register to Developer Sandbox for Red Hat OpenShift. From there, click on the red button that says Get Started in the Sandbox as shown in the following image.

Developer Sandbox Sign-up Page

Use your existing Red Hat account or create a new one, then follow the instructions on the screen. You should then be redirected to the Developer Sandbox page again, but this time, you should see a button labelled Start using your sandbox.

Developer Sandbox Start Page

Clicking on it opens up the OpenShift login screen where you can log in using the DevSandbox button, as seen below.

Log in the Developer Sandbox

Clicking this button opens up your new OpenShift cluster console.

Topology View
Quotas and Limits

Your private OpenShift environment on Developer Sandbox includes quotas and limits of:

  • 7 GB RAM

  • 15GB storage

which is enough to run this workshop.

There are two fixed projects (namespaces):

  • <your_username>-dev

  • <your_username>-stage

In this shared environment, it’s NOT possible to create a new project as in Create your First Project. This environment doesn’t support Pipelines Operator, so you can skip the OpenShift Pipelines prerequisite.

Please work in the <your_username>-dev project.

Command Line Interface

OpenShift ships with a feature rich web console as well as command line tools to provide users with a nice interface to work with applications deployed to the platform. The OpenShift tools are a single executable written in the Go programming language and is available for the following operating systems:

  • Microsoft Windows

  • Mac OS X

  • Linux

You might already have the OpenShift CLI available on your environment. You can verify it by running an oc command:

oc version

You should see the following (or something similar):

Client Version: 4.9.2
Server Version: 4.9.15 (1)
Kubernetes Version: v1.22.3+e790d7f
1 NOTE: you will only see the Server Version and Kubernetes Version if you are currently connected to a Kubenetes or OpenShift cluster

If you see output like the above you can skip to Connect to the OpenShift Cluster from CLI.

However, if the oc command doesn’t exist or you have an older version of the OpenShift CLI (e.g. < 4.4.x), select the tab appropriate to your OS and follow the instructions to install or update the OpenShift CLI.

Download OpenShift CLI

  • Mac OSX

  • Windows

  • Linux

If you have HomeBrew installed you can instead install the OpenShift CLI using the brew command. If you don’t have homebrew, then follow the manual download and install instructions that follow the inset.
Download and Install OpenShift CLI on Mac OS X using HomeBrew
brew install openshift-cli

You may also want to enable CLI autocompletion (bash or zsh):

source <(oc completion bash)
source <(oc completion zsh)

To make CLI autocompletion persistent (bash or zsh) by adding a relevant line to your .bashrc or .zshrc:

oc completion bash > oc_bash_completion.sh

source oc_bash_completion.sh
oc completion zsh > oc_zsh_completion.sh

source oc_zsh_completion.sh

From top right menu bar, click to the little white question mark icon, then click to Command Line Tools:

Download CLI

Scroll down to oc - OpenShift Command Line Interface (CLI) and click on the link appropriate to your OS

CLI Binaries

Once the file has been downloaded, you will need to extract the contents as it is a compressed archive. It is recommended that this file is saved to the following directory:

~/OpenShift

Open up a terminal window and change to the directory where you downloaded the file. Once you are in the directory, enter in the following command:

The name of the oc packaged archive may vary. Adjust accordingly. 
tar zxvf oc-macosx.tar.gz

The tar.gz file name needs to be replaced by the entire name that was downloaded in the previous step.

Now you can add the OpenShift CLI tools to your PATH.

export PATH=$PATH:~/OpenShift

At this point, we should have the oc tool available for use. Let’s test this out by printing the version of the oc command:

oc version

You should see the following (or something similar):

Client Version: 4.7.0

If you get an error message, you may not have not updated your path correctly. If after checking your PATH you still cannot get the oc command to work, contact your lab instructor for assistence.

From top right menu bar, click to the little white question mark icon, then click to Command Line Tools:

Download CLI

Scroll down to oc - OpenShift Command Line Interface (CLI) and click on the link appropriate to your OS

CLI Binaries

The CLI for Windows is provided as a zip archive. Download and unzip the archive with a ZIP program and move the oc binary to a directory on your PATH. To check your PATH, open the Command Prompt and run:

path

Checkout this blog post if you’d like to set it up with Powershell

At this point, we should have the oc tool available for use. Let’s test this out by printing the version of the oc command:

oc version

You should see the following (or something similar):

Client Version: 4.7.0

If you get an error message, you may not have not updated your path correctly. If after checking your PATH you still cannot get the oc command to work, contact your lab instructor for assistence.

From top right menu bar, click to the little white question mark icon, then click to Command Line Tools:

Download CLI

Scroll down to oc - OpenShift Command Line Interface (CLI) and click on the link appropriate to your OS

CLI Binaries

Once the file has been downloaded, you will need to extract the contents as it is a compressed archive. It is recommended that this file is saved to the following directory:

~/OpenShift

Open up a terminal window and change to the directory where you downloaded the file. Once you are in the directory, enter in the following command:

The name of the oc packaged archive may vary. Adjust accordingly. 
tar zxvf oc-linux.tar.gz

The tar.gz file name needs to be replaced by the entire name that was downloaded in the previous step.

Now you can add the OpenShift CLI tools to your PATH.

export PATH=$PATH:~/OpenShift

At this point, we should have the oc tool available for use. Let’s test this out by printing the version of the oc command:

oc version

You should see the following (or something similar):

Client Version: 4.7.0

If you get an error message, you may not have not updated your path correctly. If after checking your PATH you still cannot get the oc command to work, contact your lab instructor for assistence.

Web Terminal

OpenShift Web Console supports a web based Terminal called Web Terminal. Instead of installing the oc CLI locally, you could just run this web based terminal containing useful tools such as:

  • oc

  • kubectl

  • odo

  • helm

  • tkn

  • kn

If you want to have it in your current cluster, you can install it from OperatorHub following the documentation.

If you are using Developer Sandbox for OpenShift, this has been already installed to your cluster!

Navigate to top-right, click the command line terminal icon.

Web Terminal

From bottom-left, click the Start button.

Start Web Terminal

Start using oc from the web terminal. The session is usually already authenticated to the cluster so you can skip the following section on how to connect from CLI.

Use Web Terminal 
oc whoami

Connect to the OpenShift Cluster from CLI

Once your oc client is setup on your Workstation, you can connect to cluster and start working also with OpenShift CLI.

From Web Console overview, go to top-right menu bar and click to the dropdown menu containing your username, then click Copy Login Command:

Copy Login Command

Click on Display Token and copy the command under Login with this token:

Example:

oc login --token=some_token --server=https://c104-e.us-east.containers.cloud.ibm.com:32208
Logged into "https://c104-e.us-east.containers.cloud.ibm.com:32208" as "%USERNAME%" using the token provided.

You have access to 68 projects, the list has been suppressed. You can list all projects with 'oc projects'

Using project "default".

Getting your Quay account

Quay.io is an artifact repository for building, analyzing and distributing container images.

quay home

With the account created in Getting your OpenShift Sandbox account, you can also sign in to the Quay.io to start publishing containers.

quay login

And now that you are logged, you should see something similar as:

quay user

With a Kubernetes cluster up and running, and Quay.io account setup, it’s time to start deploying something to Kubernetes to understand the concepts behind Kubernetes.

Deploy Something

kubectl create deployment myapp --image=quay.io/rhdevelopers/quarkus-demo:v1
kubectl get events --sort-by=.metadata.creationTimestamp
LAST SEEN   TYPE     REASON              OBJECT                        MESSAGE
<unknown>   Normal   Scheduled           pod/myapp-5dcbf46dfc-ghrk4    Successfully assigned mystuff/myapp-5dcbf46dfc-ghrk4 to g
cp-5xldg-w-a-5ptpn.us-central1-a.c.ocp42project.internal
29s         Normal   SuccessfulCreate    replicaset/myapp-5dcbf46dfc   Created pod: myapp-5dcbf46dfc-ghrk4
29s         Normal   ScalingReplicaSet   deployment/myapp              Scaled up replica set myapp-5dcbf46dfc to 1
21s         Normal   Pulling             pod/myapp-5dcbf46dfc-ghrk4    Pulling image "quay.io/burrsutter/quarkus-demo:1.0.0"
15s         Normal   Pulled              pod/myapp-5dcbf46dfc-ghrk4    Successfully pulled image "quay.io/burrsutter/quarkus-dem
o:1.0.0"
15s         Normal   Created             pod/myapp-5dcbf46dfc-ghrk4    Created container quarkus-demo
15s         Normal   Started             pod/myapp-5dcbf46dfc-ghrk4    Started container quarkus-demo

Created Objects

Deployments

kubectl get deployments
NAME    READY   UP-TO-DATE   AVAILABLE   AGE
myapp   1/1     1            1           95s

Replicasets

kubectl get replicasets
NAME               DESIRED   CURRENT   READY   AGE
myapp-5dcbf46dfc   1         1         1       2m1s

Pods

kubectl get pods --show-labels
NAME                     READY   STATUS    RESTARTS   AGE     LABELS
myapp-5dcbf46dfc-ghrk4   1/1     Running   0          2m18s   app=myapp,pod-template-hash=5dcbf46dfc

Logs

kubectl logs -l app=myapp
2020-03-22 14:41:30,497 INFO  [io.quarkus] (main) Quarkus 0.22.0 started in 0.021s. Listening on: http://0.0.0.0:8080
2020-03-22 14:41:30,497 INFO  [io.quarkus] (main) Installed features: [cdi, resteasy]

Expose a Service

kubectl expose deployment myapp --port=8080 --type=LoadBalancer

Talk to the App

kubectl get services
NAME                                TYPE           CLUSTER-IP       EXTERNAL-IP                                                              PORT(S)

myapp                               LoadBalancer   172.30.30.51     a515aaf73ae40447d804bb4ba234fc89-774051193.us-east-1.elb.amazonaws.com   8080:31534/TCP                               3m9s
workspace680adb7c461a4d04-service   ClusterIP      172.30.247.111   <none>                                                                   4444/TCP

myapp is the service to access to the deployment. Wait until EXTERNAL-IP is set, it might take from 1 to 2 minutes.

curl a515aaf73ae40447d804bb4ba234fc89-774051193.us-east-1.elb.amazonaws.com:8080

If it takes more than 2 minutes create an OpenShift route:

oc expose svc myapp

kubectl get routes
NAME    HOST/PORT                                                   PATH   SERVICES   PORT   TERMINATION   WILDCARD
myapp   myapp-asotobue-dev.apps.sandbox.x8i5.p1.openshiftapps.com          myapp      8080                 None
curl myapp-asotobue-dev.apps.sandbox.x8i5.p1.openshiftapps.com

Scale the App

kubectl scale deployment myapp --replicas=3

kubectl get deployments
NAME                     READY   STATUS              RESTARTS   AGE
myapp-5dcbf46dfc-6sn2s   0/1     ContainerCreating   0          4s
myapp-5dcbf46dfc-ghrk4   1/1     Running             0          5m32s
myapp-5dcbf46dfc-z6hqw   0/1     ContainerCreating   0          4s

Updating container

Start a rolling update by changing the image:

kubectl set image deployment/myapp quarkus-demo=quay.io/rhdevelopers/myboot:v1
Supersonic Subatomic Java with Quarkus myapp-5dcbf46dfc-6sn2s:188
Supersonic Subatomic Java with Quarkus myapp-5dcbf46dfc-z6hqw:169
Aloha from Spring Boot! 0 on myapp-58b97dbd95-vxd87
Aloha from Spring Boot! 1 on myapp-58b97dbd95-vxd87
Supersonic Subatomic Java with Quarkus myapp-5dcbf46dfc-6sn2s:189
Supersonic Subatomic Java with Quarkus myapp-5dcbf46dfc-z6hqw:170
Aloha from Spring Boot! 2 on myapp-58b97dbd95-vxd87
kubectl set image deployment/myapp quarkus-demo=quay.io/rhdevelopers/myboot:v2
Bonjour from Spring Boot! 2 on myapp-7d58855c6b-6c8gd
Bonjour from Spring Boot! 3 on myapp-7d58855c6b-6c8gd
Aloha from Spring Boot! 7 on myapp-58b97dbd95-mjlwx
Bonjour from Spring Boot! 4 on myapp-7d58855c6b-6c8gd
Aloha from Spring Boot! 8 on myapp-58b97dbd95-mjlwx
Bonjour from Spring Boot! 5 on myapp-7d58855c6b-6c8gd
kubectl set image deployment/myapp quarkus-demo=quay.io/rhdevelopers/quarkus-demo:v1
Bonjour from Spring Boot! 14 on myapp-7d58855c6b-dw67s
Supersonic Subatomic Java with Quarkus myapp-5dcbf46dfc-tcfwp:3
Supersonic Subatomic Java with Quarkus myapp-5dcbf46dfc-tcfwp:4
Bonjour from Spring Boot! 15 on myapp-7d58855c6b-dw67s
Supersonic Subatomic Java with Quarkus myapp-5dcbf46dfc-tcfwp:5
Bonjour from Spring Boot! 13 on myapp-7d58855c6b-72wp8
Supersonic Subatomic Java with Quarkus myapp-5dcbf46dfc-7rkxj:1
Supersonic Subatomic Java with Quarkus myapp-5dcbf46dfc-7rkxj:2
Supersonic Subatomic Java with Quarkus myapp-5dcbf46dfc-7lf9t:1
Supersonic Subatomic Java with Quarkus myapp-5dcbf46dfc-7rkxj:3
Supersonic Subatomic Java with Quarkus myapp-5dcbf46dfc-7lf9t:2
Supersonic Subatomic Java with Quarkus myapp-5dcbf46dfc-7lf9t:3
Supersonic Subatomic Java with Quarkus myapp-5dcbf46dfc-tcfwp:6

Clean Up

kubectl delete all --all