DO180 - ch07s08

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Guided Exercise: Automatic Image Updates with OpenShift Image Change Triggers

Update an application that references container images indirectly though image streams.

Outcomes

Add an image trigger to a deployment.
Modify an image stream tag to point to a new image.
Watch the rollout of the application.
Roll back a deployment to the previous image.

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-triggers project and deploys a web application with 10 replicas.

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

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

Instructions

Log in to the OpenShift cluster as the developer user with the developer password. Use the updates-triggers project.

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

Set the updates-triggers project as the active project.

[student@workstation ~]$ oc project updates-triggers
...output omitted...

Inspect the versioned-hello image stream that the lab command created.
1. Verify that the lab command enabled the local lookup policy for the versioned-hello image stream.
```
[student@workstation ~]$ oc set image-lookup
NAME             LOCAL
versioned-hello  true
```
2. Verify that the lab command created the versioned-hello:1 image stream tag. The image stream tag refers to the image in the classroom registry by its SHA ID.
  Note
  To improve readability, the instructions truncate the SHA-256 strings.
  On your system, the commands return the full SHA-256 strings. Also, you must type the full SHA-256 string, to provide such a parameter to a command.
```
[student@workstation ~]$ oc get istag
NAME               IMAGE REFERENCE ...
versioned-hello:1  ...:8443/redhattraining/versioned-hello@sha256:66e0...105e ...
```
3. Verify that the lab command created the versioned-hello:1 image stream tag from the registry.ocp4.example.com:8443/redhattraining/versioned-hello:1-123 image.
```
[student@workstation ~]$ oc get istag versioned-hello:1 \
  -o jsonpath='{.tag.from.name}{"\n"}'
registry.ocp4.example.com:8443/redhattraining/versioned-hello:1-123
```
Inspect the Deployment object that the lab command created. Verify that the application is available from outside the cluster.
1. List the Deployment objects. The version deployment retrieved the SHA image ID from the versioned-hello:1 image stream tag. The Deployment object includes a container named versioned-hello. You use that information in a later step, when you configure the trigger.
```
[student@workstation ~]$ oc get deployment -o wide
NAME     READY ... CONTAINERS        IMAGES ...
version  10/10 ... versioned-hello   .../versioned-hello@sha256:66e0...105e ...
```
2. Open a new terminal.
3. Run the /home/student/DO180/labs/updates-triggers/curl_loop.sh script that the lab command prepared. The script sends web requests to the application in a loop. Leave the script running and do not interrupt it.
```
[student@workstation ~]$ /home/student/DO180/labs/updates-triggers/curl_loop.sh
Hi!
Hi!
Hi!
Hi!
...output omitted...
```

Add an image trigger to the Deployment object.

Switch back to the first terminal window, and then use the oc set triggers command to add the trigger for the versioned-hello:1 image stream tag to the versioned-hello container.
```
[student@workstation ~]$ oc set triggers deployment/version \
  --from-image versioned-hello:1 --containers versioned-hello
deployment.apps/version triggers updated
```

Review the definition of the trigger from the image.openshift.io/triggers annotation.

[student@workstation ~]$ oc get deployment version \
  -o jsonpath='{.metadata.annotations.image\.openshift\.io/triggers}' | jq .
[
  {
    "from": {
      "kind": "ImageStreamTag",
      "name": "versioned-hello:1"
    },
    "fieldPath": "spec.template.spec.containers[?(@.name==\"versioned-hello\")].image"
  }
]

Update the versioned-hello:1 image stream tag to point to the 1-125 tag of the registry.ocp4.example.com:8443/redhattraining/versioned-hello image. Watch the output of the curl_loop.sh script to verify that the Deployment object automatically rolls out.
1. Use the oc tag command to update the versioned-hello:1 tag.
```
[student@workstation ~]$ oc tag \
  registry.ocp4.example.com:8443/redhattraining/versioned-hello:1-125 \
  versioned-hello:1
Tag versioned-hello:1 set to registry.ocp4.example.com:8443/redhattraining/versioned-hello:1-125.
```
2. Changing the image stream tag triggered a rolling update. Watch the output of the curl_loop.sh script in the second terminal.
  Before the update, only pods that use the earlier version of the image reply. During the rolling updates, both old and new pods respond. After the update, only pods that run the latest version of the image reply. The following output probably differs on your system.
```
...output omitted...
Hi!
Hi!
Hi!
Hi!
Hi! v1.1
Hi! v1.1
Hi!
Hi! v1.1
Hi!
Hi! v1.1
Hi! v1.1
Hi! v1.1
Hi! v1.1
...output omitted...
```
  Do not stop the script.

Inspect the Deployment object and the image stream.

List the version deployment and notice that the image changed.

[student@workstation ~]$ oc get deployment version -o wide
NAME     READY ... CONTAINERS        IMAGES ...
version  10/10 ... versioned-hello   .../versioned-hello@sha256:834d...fcb4 ...

Display the details of the versioned-hello image stream. The versioned-hello:1 image stream tag points to the image with the same SHA ID as in the Deployment object.

Notice that the preceding image is still available. In the following step, you roll back to that image by specifying its SHA ID.

[student@workstation ~]$ oc describe is versioned-hello
Name:           versioned-hello
Namespace:      updates-triggers
...output omitted...

1
  tagged from registry.ocp4.example.com:8443/redhattraining/versioned-hello:1-125

  * registry.ocp4.example.com:8443/.../versioned-hello@sha256:834d...fcb4
      6 minutes ago
    registry.ocp4.example.com:8443/.../versioned-hello@sha256:66e0...105e
      37 minutes ago

Roll back the Deployment object by reverting the versioned-hello:1 image stream tag.
1. Use the oc tag command. For the source image, copy and paste the old image name and the SHA ID from the output of the preceding command.
```
[student@workstation ~]$ oc tag \
registry.ocp4.example.com:8443/redhattraining/versioned-hello@sha256:66e0...105e \
versioned-hello:1
Tag versioned-hello:1 set to registry.ocp4.example.com:8443/redhattraining/versioned-hello@sha256:66e0...105e.
```
2. Watch the output of the curl_loop.sh script in the second terminal. The pods that run the v1.0 version of the application are responding again. The following output probably differs on your system.
```
...output omitted...
Hi! v1.1
Hi! v1.1
Hi! v1.1
Hi! v1.1
Hi!
Hi! v1.1
Hi! v1.1
Hi! v1.1
Hi!
Hi! v1.1
Hi! v1.1
Hi!
Hi!
Hi!
...output omitted...
```
  Press Ctrl+C to quit the script. Close that second terminal when done.

Finish

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-triggers

Discuss Red Hat OpenShift Administration I: Operating a Production Cluster

Go to community

Version 4.12.2 versus 4.12 of DO180 course?

DRobitaille

21 lis 2023

I just noticed that there is now a version 4.12.2 of the DO180. Currently without any new updated videos. Do we have access to some sort of changelog to judge how different the new version is compared to 4.12. I'm currently in the process of reviewing the content of DO180/DO280 in preparation for my upcoming EX280 exam (based on "4.12"), so I'm wondering if it's worth studying the 4.12.2 version instead of 4.12.

470

Red Hat OpenShift Administration I: Containers & Kubernetes (DO180)

Haley_Ruccio

20 lip 2023

Deploy, manage, and troubleshoot containerized applications running as Kubernetes workloads in OpenShift clusters.Course DescriptionRed Hat OpenShift Administration I: Managing Containers and Kubernetes (DO180) prepares OpenShift cluster administrators to manage Kubernetes workloads and to collaborate with developers, DevOps engineers, system administrators, and SREs to ensure the availability of application workloads. This course focuses on managing typical end-user applications that are often accessible from a web or mobile UI and that represent most cloud-native and containerized workloads. Managing applications also includes deploying and updating their dependencies, such as databases, messaging, and authentication systems.The skills that you learn in this course apply to all versions of OpenShift, including Red Hat OpenShift on AWS (ROSA), Azure Red Hat OpenShift, and OpenShift Container Platform.This course is based on Red Hat OpenShift 4.12.Course Content SummaryManaging OpenShift clusters from the command-line interface and from the web console.Troubleshooting network connectivity between applications inside and outside an OpenShift cluster.Connecting Kubernetes workloads to storage for application data.Configuring Kubernetes workloads for high availability and reliability.Managing updates to container images, settings, and Kubernetes manifests of an application.Target AudienceSystem administrators and platform operators who are interested in managing OpenShift clusters and containerized applications.Site Reliability Engineers who are interested in maintaining and troubleshooting containerized applications on Kubernetes.System and software architects who are interested in learning and using the features and functions of an OpenShift cluster.Developers and Site Reliability Engineers that are new to container technology should enroll in Red Hat OpenShift Development I: Introduction to Containers with Podman (DO188).Recommended trainingTake our free assessment to gauge whether this offering is the best fit for your skills.Prerequisite: Containers, Kubernetes and Red Hat OpenShift Technical Overview or equivalent knowledge of Linux containers.Technology considerationsThis course requires internet access to access the cloud-based classroom environment that provides an OpenShift cluster and a remote administrator’s workstation.

Welcome to the Red Hat OpenShift Administration (DO180) group in the Red Hat Learning Community!

Deanna

18 lip 2023

We are excited to launch a space dedicated to the Red Hat Training course Red Hat OpenShift Administration I - Containers & Kubernetes! To gain the most value from this group - click the "Join Group" button in the upper right hand corner of the group home screen.We encourage group members to collaborate in this group to discuss topics, ask questions, share best practices and tips, provide course feedback, and share their accomplishments as it relates to DO180.Read more about Red Hat OpenShift Administration I here.

114

Revision: do180-4.14-b6cd706

Red Hat OpenShift Administration I: Operating a Production Cluster

Guided Exercise: Automatic Image Updates with OpenShift Image Change Triggers

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