Did you write Docker files yourself?

Yes, I wrote Docker files myself. I usually start with a base image, such as python:3.9-slim or node:14-alpine, then add necessary dependencies, copy the code, and set up the startup commands.

Here's a simple example of a Dockerfile for a Python application:

FROM python:3.9-slim
WORKDIR /app
COPY requirements.txt ./
RUN pip install -r requirements.txt
COPY . .
CMD ["python", "app.py"]

I also consider layer optimization, minimizing image size, and security (for example, running as a non-privileged user).