Best practices for writing Dockerfiles

Dockerfile

ARG DEBIAN_FRONTEND=noninteractive

# Tags should be as specific as possible
FROM ubuntu:jammy-20220815

# Set default locale in UTF-8 enabled mode
ENV LANG=C.UTF-8

# Add metadata to the image
LABEL maintainer="[email protected]"

# Use diff-friendly syntax for multi-line commands
# Do not install non-necessary packages
# Sort dependencies
# Clean non-necessary files after installing dependencies
RUN : \
    && apt-get update \
    && apt-get install --no-install-recommends -y \
        curl \
        python3 \
        python3-pip \
        sl \
    && apt-get clean \
    && rm -rf /var/lib/apt/lists/* \
    && :

# Do not cache Python dependencies
# Sort dependencies
RUN : \
    && python3 -m pip --no-cache-dir install \
        pre-commit \
        virtualenv \
    && :

# Create non-privileged user
RUN : \
    && groupadd --gid 1001 marfeel \
    && useradd --uid 1001 --gid marfeel --system --create-home --home-dir /home/marfeel marfeel \
    && :

# Do not use an extra step to change ownership of files
COPY --chown=marfeel:marfeel Dockerfile /Dockerfile

# Set non-privileged user as default
USER marfeel

# Define the default script
ENTRYPOINT ["/bin/echo"]

# Define the default arguments
CMD ["Hello from Docker"]

TODO: Add CMDand ENTRYPOINT