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Dealing with images

Goal

This project is about the basic handling of Docker images. You will:

  • build images in different versions
  • build a given image and start the container

Tools

  • Try to complete the tasks below with the help of the slides and the cheatsheet.
  • If you have any problems, you will find a fold-out block for each task describing the solution.

Task 1 - Display images

  • Display the current images on the system.
Solution (click on the arrow if you get stuck)
  • The images can be retrieved with 
    docker image ls
  • You will see the image for the VSCode container you are currently using and another one for Traefik, a reverse proxy.

Task 2 - Pulling different images

  • Pull the image nginx with the tag latest.
  • Pull the image nginx with the tag mainline.
    • The tags latest and mainline point to the same image. Docker notices this and does not download anything.
  • Populate the image nginx with the tag stable.
    • Part of the layers are cached here.
  • Display the current images on the system again.
    • The nginx images are now available with the cached tags.
Solution (click on the arrow if you get stuck)
  • The images can be pulled with 
    docker pull <image>:<tag>
  • The images can then be displayed with 
    docker image ls

Task 3 - Demo app in different versions

  • Start the demo application corewire/docker-demoapp with the tag 1.1.1.
  • Call up the demo application in the browser.
  • The version is displayed accordingly.
  • Start the demo application with the tag 1.0.
  • Check which version is displayed in the browser.
  • Start the demo application with the tag latest.
  • Check in the browser which version is displayed.
Solution (click on the arrow if you get stuck)

To start a demo application, use the following command: 

docker run -p 8080:5000 corewire/docker-demoapp:<tag>

Task 4 - Build images

  • Change to the directory docker-demoapp.
Solution (click on the arrow if you get stuck)

The directory can be changed with cd <path to directory>: 

cd docker-demoapp

  • Build the Docker image. More details on docker build will be explained later. 
    docker build -t my-great-image .
  • Display the current images on the system again.
  • The image is now available locally.

Task 5 - Starting the container

  • Start the container with : 

    docker run -p 8080:5000 my-great-image

  • Call up the demo application in the browser. It is accessable via your URL (code-{NUMBER}.labs.corewire.de) on port 8080. Use http:// and not https://.