docker_basic

Sample Docker Demo

A tiny demo that shows how to package and run a minimal Python app inside Docker.

This repository contains a single Python script and a Dockerfile that builds a small container image which runs the script.

Files

• app.py: Minimal Python script. When run it prints "Hello World from inside Docker!".
• Dockerfile: Dockerfile using python:3.11-slim, copies app.py and runs it.

Prerequisites

• Docker: install Docker Desktop for Windows or Docker Engine. Verify with:

docker --version

• (Optional) Python 3.11 if you want to run the script locally:

python --version

Quick Start — Build and Run with Docker

Open a PowerShell terminal in the project folder (where Dockerfile lives) and run:

# Build the image (tag it as sample-docker-demo)
docker build -t sample-docker-demo .

# Run the container (it will print the message and exit)
docker run --rm sample-docker-demo

Expected output:

Hello World from inside Docker!

Run Locally (without Docker)

If you just want to run the Python script on your host:

python app.py

Inspecting the Image / Container

• List local images:

docker images

• Start an interactive shell inside the image (useful for debugging). Note: python:3.11-slim provides a POSIX shell:

docker run --rm -it --entrypoint sh sample-docker-demo

Tips & Troubleshooting

• If the build fails, ensure Docker is running and you are in the correct folder that contains the Dockerfile and app.py.
• If you don’t see the expected output, run the container interactively to inspect files and environment (see previous section).
• Use docker logs <container-id> for troubleshooting long-running containers.

Extending this demo

• Add more Python files and update COPY/CMD in the Dockerfile.
• Add requirements.txt and RUN pip install -r requirements.txt to install dependencies.

License This demo is provided as-is and may be used freely for learning and experimentation.