🐳 Project 1.1: Hello Docker

The Goal

Create and run my first Docker container. Simple goal: a Dockerfile that executes a Python “Hello World” script. No overthinking—just get containers working.

What I Built

A minimal Docker setup that:

• Builds an image from a Dockerfile
• Runs a Python script inside the container
• Outputs “Hello World” (and proves I understand the basics)

Tech Stack

• Docker — Container runtime
• Python — Simple script execution

Implementation

Dockerfile

FROM python:3.11-slim
 
WORKDIR /app
 
COPY hello.py .
 
CMD ["python", "hello.py"]

Python Script

# hello.py
print("Hello from Docker!")
print("Container is working.")

Commands

# Build the image
docker build -t hello-docker .
 
# Run the container
docker run hello-docker

What I Learned

• Docker fundamentals: Images vs containers, build vs run
• Dockerfile syntax: FROM, WORKDIR, COPY, CMD
• Layer caching: Order matters in Dockerfiles
• Image tagging: How -t names your images

Challenges

Challenge: Docker Desktop eating RAM on my Mac. Solution: Adjusted resource limits in Docker Desktop settings. 4GB RAM is enough for basic containers.

Challenge: Forgetting to rebuild after changes. Solution: docker build doesn’t auto-detect changes. Need to rebuild manually (or use docker-compose later).

Result

Container runs, prints output, exits cleanly. First Docker project: done. ✅

$ docker run hello-docker
Hello from Docker!
Container is working.

Simple, but it works. Foundation for everything else.

Related

• de-project-1-2-postgresql-in-docker
• 0-Data-Engineering-Fundamentals
• 10-Python-for-Data-Engineering
• fixing-immich-installation

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Project: 1.1 of 28 | Month: January | Hours: ~3h GitHub: 1-1_Hello-Docker