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Introduction to Containers with Docker, Kubernetes & OpenShift

From IBM on Coursera

Peer-graded Assignment: Build and Deploy a Simple Guestbook

Results available under screenshots/assignment (file names imposed by the instructions)

Build the Guestbook app

Clone the git repository that contains the artifacts needed for this lab

[ ! -d 'guestbook' ] && git clone https://github.com/ibm-developer-skills-network/guestbook

Change to the directory for this lab

cd guestbook/v1/guestbook

Complete the Dockerfile ( multi-stage builds ) with the necessary commands to build and push your image

  • The FROM instruction initializes a new build stage and specifies the base image that subsequent instructions will build upon
  • The COPY command enables us to copy files to our image
  • The ADD command is used to copy files/directories into a Docker image
  • The RUN instruction executes commands
  • The EXPOSE instruction exposes a particular port with a specified protocol inside a Docker container
  • The CMD instruction provides a default for executing a container, or in other words, an executable that should run in your container

Export your namespace as an environment variable so that it can be used in subsequent commands

export MY_NAMESPACE=sn-labs-$USERNAME

Build the Guestbook app

docker build . -t us.icr.io/$MY_NAMESPACE/guestbook:v1

Push the image to IBM Cloud Container Registry

docker push us.icr.io/$MY_NAMESPACE/guestbook:v1

Verify that the image was pushed successfully

ibmcloud cr images

To check your namespace

ibmcloud cr namespaces

Apply the Deployment

kubectl apply -f deployment.yml

To view your app, open a new terminal

kubectl port-forward deployment.apps/guestbook 3000:3000

Launch your app on port 3000 (Skills Network)

Autoscale the Guestbook app using Horizontal Pod Autoscaler

Autoscale the Deployment

kubectl autoscale deployment guestbook --cpu-percent=5 --min=1 --max=10

You can check the current status of the newly-made Horizontal Pod Autoscaler

kubectl get hpa guestbook

To generate load on the app and observe the autoscaling, open another new terminal

kubectl run -i --tty load-generator --rm --image=busybox:1.36.0 --restart=Never -- /bin/sh -c "while sleep 0.01; do wget -q -O- <your-app-url>; done"

To observe the replicas increase in accordance with the autoscaling

kubectl get hpa guestbook --watch

Perform rolling updates and rollbacks on the Guestbook app

To build and push your updated app image

docker build . -t us.icr.io/$MY_NAMESPACE/guestbook:v1 && docker push us.icr.io/$MY_NAMESPACE/guestbook:v1

Apply other changes

kubectl apply -f deployment.yml

Open a new terminal and run the port-forward command again to start the app

kubectl port-forward deployment.apps/guestbook 3000:3000

To see the history of Deployment rollouts

kubectl rollout history deployment/guestbook

To see the details of Revision of the Deployment rollout

kubectl rollout history deployments guestbook --revision=2

To get the ReplicaSets and observe the Deployment which is being used now

kubectl get rs

To undo the Deploymnent

kubectl rollout undo deployment/guestbook --to-revision=1 && kubectl get rs

Optional: Deploy Guestbook App from the OpenShift Internal Registry

Results available under screenshots/optional

Deploy

Create an ImageStream that points to your image in IBM Cloud Container Registry

oc tag us.icr.io/$MY_NAMESPACE/guestbook:v1 guestbook:v1 --reference-policy=local --scheduled
  1. Click on Open OpenShift Console under Skills Network Toolbox
  2. From Developer click Add, then Container image
  3. Switch to Image stream tag from internal registry, then select your project
  4. Keep all the default values and hit Create
  5. From Topology click the guestbook Deployment, this should take you to the Resources
    • Do not delete the opensh.console Deployment in Topology as this is essential for the OpenShift Console to function properly

Update

Let’s update the Guestbook app and see how OpenShift’s image streams can help us update our apps with ease

docker build . -t us.icr.io/$MY_NAMESPACE/guestbook:v1 && docker push us.icr.io/$MY_NAMESPACE/guestbook:v1

oc import-image guestbook:v1 --from=us.icr.io/$MY_NAMESPACE/guestbook:v1 --confirm

Switch to Administrator > Builds > ImageStreams > guestbook > History

View the guestbook in the browser again, OpenShift imported the new version of our image, and since the Deployment points to the image stream, it began running this new version as well

Storage

Topology > guestbook-app > Actions > Delete application

cd ../../v2

To familiarize yourself with the Deployment configuration for the Redis master

Redis is an open source, in-memory data structure store, used as a database, cache and message broker

cat redis-master-deployment.yaml

Create the Redis master Deployment

oc apply -f redis-master-deployment.yaml && oc get deployments

List Pods to see the Pod created by the Deployment.

oc get pods

To familiarize yourself with the Service configuration for the Redis master

cat redis-master-service.yaml

Create the Redis master Service

oc apply -f redis-master-service.yaml

Developer > Topology > redis-master > resources

To familiarize yourself with the Deployment configuration for the Redis slave

cat redis-slave-deployment.yaml

Create the Redis slave Deployment

oc apply -f redis-slave-deployment.yaml && oc get deployments

List Pods to see the Pod created by the Deployment

oc get pods

To familiarize yourself with the Service configuration for the Redis slave

cat redis-slave-service.yaml

Create the Redis slave Service

oc apply -f redis-slave-service.yaml

Developer > Topology > redis-slave > resources

Now it’s time to deploy the second version of the Guestbook app, which will leverage Redis for persistent storage

  1. From Developer click Add, then Import from Git
    • https://github.com/ibm-developer-skills-network/guestbook
  2. Show advanced Git options
    • Context dir > /v2/guestbook
    • Target port > 3000

Developer > Topology > guestbook > Routes

oc status