Dockerfile

# Use a slim Python image for smaller size
FROM python:3.10-slim

# --- User Setup for Security and Writable Config Dirs ---
# Define build arguments for a non-root username and user ID
ARG NB_USER=appuser
ARG NB_UID=1000

# Set environment variables for the user and their home directory
ENV USER ${NB_USER}
ENV HOME /home/${NB_USER}

# Create the non-root user, set up their home directory, and grant ownership
RUN adduser --disabled-password --gecos "" --uid ${NB_UID} ${NB_USER} \
    && mkdir -p ${HOME}/.config \
    && chown -R ${NB_USER}:${NB_USER} ${HOME}

# Set environment variables for Matplotlib and Ultralytics
# These direct them to use a writable directory within the user's home
ENV MPLCONFIGDIR=${HOME}/.config/matplotlib
ENV YOLO_CONFIG_DIR=${HOME}/.config/ultralytics

# Ensure the directories exist and are writable by the non-root user
RUN mkdir -p ${MPLCONFIGDIR} \
    && mkdir -p ${YOLO_CONFIG_DIR} \
    && chown -R ${NB_USER}:${NB_USER} ${MPLCONFIGDIR} \
    && chown -R ${NB_USER}:${NB_USER} ${YOLO_CONFIG_DIR}

# --- System Dependencies ---
# Switch to root to install system-level packages
USER root
RUN apt-get update && apt-get install -y --no-install-recommends \
    libgl1 \
    libglib2.0-0 \
    curl \
    # Clean up apt caches to keep image size small
    && rm -rf /var/lib/apt/lists/*

# --- Application Setup ---
# Set the working directory for the application
WORKDIR /app

# Switch back to the non-root user for installing Python packages and copying application code
USER ${NB_USER}

# Copy requirements.txt and install Python packages
# Ensure Flask is in your requirements.txt (and gunicorn is NOT if you're not using it)
COPY requirements.txt .
RUN pip install --no-cache-dir -r requirements.txt

# Copy the rest of your application's source code
COPY . .

# --- Flask Development Server Configuration ---
# Set Flask application entry point
ENV FLASK_APP=app.py

# Set FLASK_RUN_HOST to listen on all interfaces
ENV FLASK_RUN_HOST=0.0.0.0
# Set FLASK_RUN_PORT (optional, defaults to 5000)
ENV FLASK_RUN_PORT=5000

# Set FLASK_ENV to 'development' if you want auto-reload and debugger.
# For a more "production-like" test without Gunicorn, use 'production'
# but be aware of the limitations mentioned previously (not for real production traffic).
ENV FLASK_ENV=development

# Expose the port Flask will listen on
EXPOSE 5000

# Command to run the Flask application directly
# Using 'python -m flask run' is the recommended way.
CMD ["python", "-m", "flask", "run"]

# Alternative CMD if your app.py contains app.run() directly:
# CMD ["python", "app.py"]