Lab: Deploy Web Applications

Use image streams with Kubernetes workload resources to ensure reproducibility of application deployments.

Configure applications by using Kubernetes secrets to initialize environment variables.

Provide applications with persistent storage volumes.

Expose applications to clients outside the cluster.

Outcomes

You should be able to create and configure OpenShift and Kubernetes resources, such as projects, secrets, deployments, persistent volumes, services, and routes.

As the student user on the workstation machine, use the lab command to prepare your system for this exercise.

This command ensures that all resources are available for this exercise. The command also creates the /home/student/DO180/labs/compreview-deploy/resources.txt file. The resources.txt file contains the URLs of your OpenShift cluster and the image names that you use in the exercise. You can use the file to copy and paste these URLs and image names.

[student@workstation ~]$ lab start compreview-deploy

Specifications

The API URL of your OpenShift cluster is https://api.ocp4.example.com:6443, and the oc command is already installed on your workstation machine.

The URL of the OpenShift web console is https://console-openshift-console.apps.ocp4.example.com. When you access the web console, select Red Hat Identity Management as the authentication mechanism.

Log in to the OpenShift cluster as the developer user with the developer password. The password for the admin user is redhatocp, although you do not need administrator privileges to complete the exercise.

In this exercise, you deploy a web application and its database for testing purposes. The resulting configuration is not ready for production, because you do not configure probes and resource limits, which are required for production. Another comprehensive review exercise covers these subjects.

Perform the following tasks to complete the exercise:

  • Create a project named review to store your work.

  • Configure your project so that its workloads refer to the database image by the mysql8:1 short name.

    • The short name must point to the registry.ocp4.example.com:8443/rhel9/mysql-80:1-228 container image. The database image name and its source registry are expected to change in the near future, and you want to isolate your workloads from that change.

      The classroom setup copied the image from the Red Hat Ecosystem Catalog. The original image is registry.redhat.io/rhel9/mysql-80:1-228.

    • Ensure that the workload resources in the review project can use the mysql8:1 resource. You create these workload resources in a later step.

  • Create the dbparams secret to store the MySQL database parameters. Both the database and the front-end deployment need these parameters. The dbparams secret must include the following variables:

    NameValue
    user operator1
    password redhat123
    database quotesdb

  • Create the quotesdb deployment and configure it as follows:

    • Use the mysql8:1 image for the deployment.

    • The database must automatically roll out whenever the source container in the mysql8:1 resource changes.

      To test your configuration, you can change the mysql8:1 image to point to the registry.ocp4.example.com:8443/rhel9/mysql-80:1-237 container image that the classroom provides, and then verify that the quotesdb deployment rolls out. Remember to reset the mysql8:1 image to the registry.ocp4.example.com:8443/rhel9/mysql-80:1-228 container image before grading your work.

    • Define the following environment variables in the deployment from the keys in the dbparams secret:

      Environment variable dbparams secret key
      MYSQL_USER user
      MYSQL_PASSWORD password
      MYSQL_DATABASE database

    • Ensure that OpenShift preserves the database data between pod restarts. This data does not consume more than 2 GiB of disk space. The MySQL database stores its data under the /var/lib/mysql directory. Use the lvms-vg1 storage class for the volume.

  • Create a quotesdb service to make the database available to the front-end web application. The database service is listening on port 3306.

  • Create the frontend deployment and configure it as follows:

    • Use the registry.ocp4.example.com:8443/redhattraining/famous-quotes:2-42 image. For this deployment, you refer to the image by its full name, because your organization develops the image and controls its release process.

    • Define the following environment variables in the deployment:

      Environment variable nameValue
      QUOTES_USER The user key from the dbparams secret
      QUOTES_PASSWORD The password key from the dbparams secret
      QUOTES_DATABASE The database key from the dbparams secret
      QUOTES_HOSTNAME quotesdb

  • You cannot yet test the application from outside the cluster. Expose the frontend deployment so that the application can be reached at http://frontend-review.apps.ocp4.example.com.

    The frontend deployment is listening to port 8000.

    When you access the http://frontend-review.apps.ocp4.example.com URL, the application returns a list of quotations from famous authors.

  1. Log in to the OpenShift cluster from the command line, and then create the review project.

    1. Log in as the developer user.

      [student@workstation ~]$ oc login -u developer -p developer \
  https://api.ocp4.example.com:6443
Login successful.
...output omitted...

    2. Create the review project.

      [student@workstation ~]$ oc new-project review
Now using project "review" on server "https://api.ocp4.example.com:6443".
...output omitted...

  2. Create the mysql8:1 image stream tag from the registry.ocp4.example.com:8443/rhel9/mysql-80:1-228 image. Enable image stream resolution for the mysql8 image stream so that Kubernetes resources in the current project can use it.

    1. Use the oc create istag command to create the image stream and the image stream tag.

      [student@workstation ~]$ oc create istag mysql8:1 \
  --from-image registry.ocp4.example.com:8443/rhel9/mysql-80:1-228
imagestreamtag.image.openshift.io/mysql8:1 created

    2. Use the oc set image-lookup command to enable image lookup resolution.

      [student@workstation ~]$ oc set image-lookup mysql8
imagestream.image.openshift.io/mysql8 image lookup updated

    3. Run the oc set image-lookup command without any arguments to verify your work.

      [student@workstation ~]$ oc set image-lookup
NAME    LOCAL
mysql8  true

  3. Create the dbparams secret.

    [student@workstation ~]$ oc create secret generic dbparams \
  --from-literal user=operator1 --from-literal password=redhat123 \
  --from-literal database=quotesdb
secret/dbparams created

  4. Create the quotesdb deployment from the mysql8:1 image stream tag. Set the number of replicas to zero, to prevent OpenShift from deploying the database before you finish its configuration.

    [student@workstation ~]$ oc create deployment quotesdb --image mysql8:1 \
  --replicas 0
deployment.apps/quotesdb created

  5. Add an image trigger to the quotesdb deployment.

    1. Retrieve the name of the container from the quotesdb deployment.

      [student@workstation ~]$ oc get deployment quotesdb -o wide
NAME       READY   UP-TO-DATE   AVAILABLE   AGE   CONTAINERS ...
quotesdb   0/0     0            0           11s   mysql8     ...

    2. Use the oc set triggers command to add the trigger for the mysql8:1 image stream tag to the mysql8 container.

      [student@workstation ~]$ oc set triggers deployment/quotesdb \
  --from-image mysql8:1 --containers mysql8
deployment.apps/quotesdb triggers updated

  6. Add environment variables to the quotesdb deployment from the dbparams secret. Add the MYSQL_ prefix to each variable name.

    [student@workstation ~]$ oc set env deployment/quotesdb \
  --from secret/dbparams --prefix MYSQL_
deployment.apps/quotesdb updated

  7. Add a 2 GiB persistent volume to the quotesdb deployment. Use the lvms-vg1 storage class. Inside the pods, mount the volume under the /var/lib/mysql directory.

    [student@workstation ~]$ oc set volumes deployment/quotesdb --add \
  --claim-class lvms-vg1 --claim-size 2Gi --mount-path /var/lib/mysql
info: Generated volume name: volume-n7xpd
deployment.apps/quotesdb volume updated

  8. Start the database by scaling up the quotesdb deployment to one replica.

    1. Scale up the deployment.

      [student@workstation ~]$ oc scale deployment/quotesdb --replicas 1
deployment.apps/quotesdb scaled

    2. Wait for the pod to start. You might have to rerun the command several times for the pod to report a Running status. The name of the pod on your system probably differs.

      [student@workstation ~]$ oc get pods
NAME                       READY   STATUS    RESTARTS   AGE
quotesdb-99f9b4ff8-ggs7z   1/1     Running   0          4s

  9. Create the quotesdb service for the quotesdb deployment. The database server is listening on port 3306.

    1. Use the oc expose deployment command to create the service.

      [student@workstation ~]$ oc expose deployment quotesdb --port 3306
service/quotesdb exposed

    2. Verify that OpenShift associates the IP address of the MySQL server with the endpoint. The endpoint IP address on your system probably differs.

      [student@workstation ~]$ oc describe service quotesdb
Name:              quotesdb
Namespace:         review
...output omitted...
TargetPort:        3306/TCP
Endpoints:         10.8.0.123:3306
Session Affinity:  None
Events:            <none>

  10. Create the frontend deployment from the registry.ocp4.example.com:8443/redhattraining/famous-quotes:2-42 image. Set the number of replicas to zero, to prevent OpenShift from deploying the application before you finish its configuration.

    [student@workstation ~]$ oc create deployment frontend \
  --image registry.ocp4.example.com:8443/redhattraining/famous-quotes:2-42 \
  --replicas 0
deployment.apps/frontend created

  11. Add environment variables to the frontend deployment from the dbparams secret, and add the QUOTES_HOSTNAME variable with the quotesdb value.

    1. Add the variables from the dbparams secret. Add the QUOTES_ prefix to each variable name.

      [student@workstation ~]$ oc set env deployment/frontend \
  --from secret/dbparams --prefix QUOTES_
deployment.apps/frontend updated

    2. Declare the QUOTES_HOSTNAME variable.

      [student@workstation ~]$ oc set env deployment/frontend QUOTES_HOSTNAME=quotesdb
deployment.apps/frontend updated

  12. Start the application by scaling up the frontend deployment to one replica.

    1. Scale up the deployment.

      [student@workstation ~]$ oc scale deployment/frontend --replicas 1
deployment.apps/frontend scaled

    2. Wait for the pod to start. You might have to rerun the command several times for the pod to report a Running status. The name of the pod on your system probably differs.

      [student@workstation ~]$ oc get pods
NAME                       READY   STATUS    RESTARTS   AGE
frontend-86cdd7c7bf-hpnwz  1/1     Running   0          44s
quotesdb-99f9b4ff8-ggs7z   1/1     Running   0          2m11s

  13. Expose the frontend deployment so that the application is accessible from outside the cluster. The web application is listening on port 8000.

    1. Create the frontend service for the frontend deployment.

      [student@workstation ~]$ oc expose deployment frontend --port 8000
service/frontend exposed

    2. Create the route.

      [student@workstation ~]$ oc expose service frontend
route.route.openshift.io/frontend exposed

    3. Retrieve the application URL from the route.

      [student@workstation ~]$ oc get route
NAME       HOST/PORT                               PATH   SERVICES ...
frontend   frontend-review.apps.ocp4.example.com          frontend ...

    4. Use the curl command to test the application.

      [student@workstation ~]$ curl http://frontend-review.apps.ocp4.example.com
<html>
	<head>
        <title>Quotes</title>
    </head>
    <body>

        <h1>Quote List</h1>

            <ul>

                    <li>1: When words fail, music speaks.
- William Shakespeare
</li>
...output omitted...

Evaluation

As the student user on the workstation machine, use the lab command to grade your work. Correct any reported failures and rerun the command until successful.

[student@workstation ~]$ lab grade compreview-deploy

Finish

As the student user on the workstation machine, use the lab command to complete this exercise. This step is important to ensure that resources from previous exercises do not impact upcoming exercises.

[student@workstation ~]$ lab finish compreview-deploy