Docker/Python Hello World

This is a simple docker tutorial for building and running a python Hello World application. Dockerfile has been excluded for the sake of the building exercise, and application exits immediately after running the print("Hello World!) command.

Prerequisites

• Docker Desktop
• git
• python 3
• VS Code
• VS Code Extension: Docker

1. Clone Repository

• cd to target directory
• git clone "https://github.com/alexfricker/docker-python-hello-world.git"
• main.py contains code that will be executed

2. Add Dockerfile

• Open VS Code
• Open directory where repo was cloned
  • if prompted, select a python interpreter version
• Press "F1" and type "docker add". Select "Docker: Add Docker Files to Workspace..."
  • Select "Python: General"
  • Select "main.py" as the entry point
  • Select "No" for including optional Docker Compose files
• Inspect generated docker files:
  • Dockerfile
    • contains specifications for docker image
  • requirements.txt
    • contains list of required python libraries

3. Build Docker Image

• Press "F1" and type "docker add". Select "Docker Images: Build Image..."
• Close terminal that was opened for build
• Open Docker extension to see new image
  • new image created under "Images" pane
  • named the same as the folder you built the files from

4. Run Docker Image in a Container

Terminal

docker run dockerpythonhelloworld

VS Code

• Right click tagged image and select "Run" (or execute code above)
• Attach a terminal by right clicking the running container (assuming it is still running) and selecting "Attach Shell"

Docker Desktop

• Open Docker Desktop
• Select "Images" to see local images (same list as VS Code)
• Hover over "dockerpythonhelloworld" and select "Run" to create and start a container with this image
  • Leave optional settings blank and select "Run"
• Examine logs (Containers > Select container name > Logs)
  • Shows "Hello World!" and container stopped after execution
• Re-run container (Click the run/play button) to see log entries for each execution

5. Next Steps

• Add a sleep command to prevent the container from immediately closing
  • import time time.sleep(600)
  • rebuild, re-run
  • open a CLI through Docker Desktop - ">_" icon
  • explore filesystem
• Add additional files and try to get them to copy to the container (hint: review the Dockerfile)
• Add additional code for other tasks and try to build and run