Red Hat OpenShift Development I: Introduction to Containers with Podman

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Lab: Container Images

Use Podman to create and pull an image from a container registry.

Outcomes

You should be able to:

  • Create a container image from a Containerfile by using Quay.

  • Pull an image from the Quay container registry.

  • Add a tag to a container image.

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

This command verifies that Podman is available and provides a Containerfile template.

The lab script continuously evaluates the objectives of this lab. Keep the script running in a terminal window and complete the objectives of this lab from a new terminal window.

After each objective, return to the lab script evaluation to see if you have finished the objective successfully. When you finish all objectives, the lab command prompts you to execute the finish function.

[student@workstation ~]$ lab start images-lab

Instructions

  1. Build a container image that uses the ~/DO188/labs/images-lab/Containerfile file.

    Call the resulting image images-lab and push the image into the registry.ocp4.example.com:8443 registry in the developer user repository.

    Use the developer user with the developer password to authenticate with the registry.ocp4.example.com:8443 registry.

    1. Authenticate Podman with the registry.ocp4.example.com:8443 registry.

      [student@workstation ~]$ podman login -u developer -p developer \
 registry.ocp4.example.com:8443
Login Succeeded!

    2. In a terminal, change into the ~/DO188/labs/images-lab directory.

      [student@workstation ~]$ cd ~/DO188/labs/images-lab
no output expected

    3. Build the Containerfile with the registry.ocp4.example.com:8443/developer/images-lab container image name.

      [student@workstation images-lab]$ podman build --file Containerfile \
  --tag registry.ocp4.example.com:8443/developer/images-lab
...output omitted...
Successfully tagged registry.ocp4.example.com:8443/developer/images-lab:latest
8d14...dd5a

    4. Push the image to the registry.ocp4.example.com:8443 registry.

      [student@workstation images-lab]$ podman push \
  registry.ocp4.example.com:8443/developer/images-lab
...output omitted...
Writing manifest to image destination
Storing signatures

  2. Add the grue tag to the images-lab container image, and push it to the registry.ocp4.example.com:8443 registry.

    1. Add the grue tag to the image.

      [student@workstation images-lab]$ podman tag \
  registry.ocp4.example.com:8443/developer/images-lab \
  registry.ocp4.example.com:8443/developer/images-lab:grue
no output expected

    2. Push the new image tag.

      [student@workstation images-lab]$ podman push \
  registry.ocp4.example.com:8443/developer/images-lab:grue
...output omitted...
Writing manifest to image destination
Storing signatures

  3. Create a container by using the images-lab:grue image. Use the images-lab container name, and bind the 8080 container port to the 8080 host port. Start the container in the background.

    Optionally, use the curl command to verify that the HTTP server is running.

    1. Start the container.

      [student@workstation images-lab]$ podman run -d --name images-lab \
-p 8080:8080 images-lab:grue
2422...e7b1

    2. Connect to the HTTP server by using curl. Note that this step is not required to make the lab script pass.

      [student@workstation images-lab]$ curl localhost:8080
It is pitch black. You are likely to be eaten by a grue.

Finish

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

Press y when the lab start command prompts you to execute the finish function. Alternatively, execute the following command:

[student@workstation ~]$ lab finish images-lab

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Revision: do188-4.14-8c43a16