ch07s09 - Red Hat OpenShift Administration I: Operating a Production Cluster

Lab: Manage Application Updates

Update two live applications to their latest releases as identified by non-floating tags.

Outcomes

You should be able to configure Deployment objects with images and triggers, and configure image stream tags and aliases.

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. It also creates the updates-review project and deploys two applications, app1 and app2, in that project.

The command creates the /home/student/DO180/labs/updates-review/resources.txt file. The resources.txt file contains the name of the images that you use during the exercise. You can use the file to copy and paste these image names.

[student@workstation ~]$ lab start updates-review

Instructions

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.

Log in to the OpenShift cluster as the developer user with the developer password. Use the updates-review project for your work.

Your team created the app1 deployment in the updates-review project from the registry.ocp4.example.com:8443/redhattraining/php-ssl:latest container image. Recently, a developer in your organization pushed a new version of the image and then reassigned the latest tag to that version.
Reconfigure the app1 deployment to use the 1-222 static tag instead of the latest floating tag, to prevent accidental redeployment of your application with untested image versions that your developers can publish at any time.
Log in to the OpenShift cluster.
[student@workstation ~]$ oc login -u developer -p developer \ https://api.ocp4.example.com:6443 Login successful. ...output omitted...
Set the updates-review project as the active project.
[student@workstation ~]$ oc project updates-review ...output omitted...
Verify that the app1 deployment uses the latest tag. Retrieve the container name.
[student@workstation ~]$ oc get deployment/app1 -o wide NAME READY ... CONTAINERS IMAGES ... app1 1/1 ... php-ssl registry...:8443/redhattraining/php-ssl:latest ...
In the Deployment object, change the image to registry.ocp4.example.com:8443/redhattraining/php-ssl:1-222.
[student@workstation ~]$ oc set image deployment/app1 \ php-ssl=registry.ocp4.example.com:8443/redhattraining/php-ssl:1-222 deployment.apps/app1 image updated
Verify your work.
[student@workstation ~]$ oc get deployment/app1 -o wide NAME READY ... CONTAINERS IMAGES ... app1 1/1 ... php-ssl registry...:8443/redhattraining/php-ssl:1-222 ...

The app2 deployment is using the php-ssl:1 image stream tag, which is an alias for the php-ssl:1-222 image stream tag.

Enable image triggering for the app2 deployment, so that whenever the php-ssl:1 image stream tag changes, OpenShift rolls out the application. You test your configuration in a later step, when you reassign the php-ssl:1 alias to a new image stream tag.

Retrieve the container name from the Deployment object.

[student@workstation ~]$ oc get deployment/app2 -o wide
NAME   READY   UP-TO-DATE   AVAILABLE   AGE   CONTAINERS  ...
app2   1/1     1            1           21m   php-ssl     ...

Add the image trigger to the Deployment object.

[student@workstation ~]$ oc set triggers deployment/app2 \
  --from-image php-ssl:1 --containers php-ssl
deployment.apps/app2 triggers updated

Verify your work.

[student@workstation ~]$ oc set triggers deployment/app2
NAME              TYPE    VALUE                AUTO
deployments/app2  config                       true
deployments/app2  image   php-ssl:1 (php-ssl)  true

A new image version, registry.ocp4.example.com:8443/redhattraining/php-ssl:1-234, is available in the container registry. Your QA team tested and approved that version. It is ready for production.

Create the php-ssl:1-234 image stream tag that points to the new image. Move the php-ssl:1 image stream tag alias to the new php-ssl:1-234 image stream tag. Verify that the app2 application redeploys.

Create the php-ssl:1-234 image stream tag.

[student@workstation ~]$ oc create istag php-ssl:1-234 \
  --from-image registry.ocp4.example.com:8443/redhattraining/php-ssl:1-234
imagestreamtag.image.openshift.io/php-ssl:1-234 created

Move the php-ssl:1 alias to the new php-ssl:1-234 image stream tag.

[student@workstation ~]$ oc tag --alias php-ssl:1-234 php-ssl:1
Tag php-ssl:1 set up to track php-ssl:1-234.

Verify that the app2 application rolls out. The names of the replica sets on your system probably differ.

[student@workstation ~]$ oc describe deployment/app2
Name:                   app2
Namespace:              updates-review
...output omitted...
Events:
  Type    ...  Age         Message
  ----         ----        -------
  Normal  ...  33m    ...  Scaled up replica set app2-7dd589f6d5 to 1
  Normal  ...  3m30s  ...  Scaled up replica set app2-7bf5b7787 to 1
  Normal  ...  3m28s  ...  Scaled down replica set app2-7dd589f6d5 to 0 from 1

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 updates-review

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 updates-review