Dockerfile

# 1. Start from a slim Python 3.11 base image
FROM python:3.11-slim

# 2. Set Environment Variables
# - DEBIAN_FRONTEND: Prevents installers from asking interactive questions
# - PYTHONUNBUFFERED/PYTHONDONTWRITEBYTECODE: Standard Python-in-Docker settings
# - PYVISTA_OFF_SCREEN/DISPLAY: Crucial for running PyVista headless (off-screen)
#   by telling it to use a "virtual" display at address :99
ENV DEBIAN_FRONTEND=noninteractive \
    PYTHONUNBUFFERED=1 \
    PYTHONDONTWRITEBYTECODE=1 \
    HOME=/home/user \
    PATH=/home/user/.local/bin:$PATH \
    PYVISTA_OFF_SCREEN=true \
    DISPLAY=:99 \
    VTK_SILENCE_GET_VOID_POINTER_WARNINGS=1

# 3. Install System Dependencies
# This is the most critical part for PyVista/VTK. We need the OS
# graphics libraries (libosmesa, libgl1) and the X Virtual FrameBuffer (xvfb).
#
# *** UPDATED this section to use current package names (e.g., libgl1, libegl1) ***
#
RUN apt-get update && apt-get install -y --no-install-recommends \
  build-essential cmake wget xvfb nginx \
    libosmesa6 libosmesa6-dev \
    libgl1 libgl1-mesa-dev \
    libegl1 libegl1-mesa-dev \
    libglu1-mesa libglu1-mesa-dev \
    libgles2-mesa-dev \
    libx11-6 libxt6 libxrender1 libsm6 libice6 \
    && rm -rf /var/lib/apt/lists/*

# 4. Create a non-root user for security
RUN useradd -m -u 1000 user
WORKDIR /home/user/app

# 5. Install Python dependencies (optimized)
# We copy *only* requirements.txt first and install it.
# This "layer" is cached by Docker. If you only change app.py later,
# Docker skips this step, making builds much faster.
COPY requirements.txt .
RUN python3 -m pip install --upgrade pip setuptools wheel \
 && python3 -m pip install --no-cache-dir -r requirements.txt

# 6. Copy the rest of the application code
# This copies app.py, delta_impulse_generator.py, etc.
# We set the owner to our new 'user'.
COPY --chown=user:user . .
COPY docker/nginx.conf /etc/nginx/nginx.conf

# Prepare writable directories for nginx (running as non-root later)
RUN mkdir -p /tmp/nginx/body /tmp/nginx/proxy /tmp/nginx/fastcgi /tmp/nginx/uwsgi /tmp/nginx/scgi \
  && touch /tmp/nginx.access.log /tmp/nginx.error.log \
  && chown -R user:user /tmp/nginx /tmp/nginx.access.log /tmp/nginx.error.log

# 7. Switch to the non-root user
USER user

# Default runtime configuration for multiprocess layout
ENV OMP_NUM_THREADS=1 \
  APP_HOST=127.0.0.1 \
  APP_PORT=8700 \
  EM_APP_PORT=8701 \
  QLBM_APP_PORT=8702 \
  EM_HOST=127.0.0.1 \
  QLBM_HOST=127.0.0.1 \
  EM_IFRAME_SRC=/em/ \
  QLBM_IFRAME_SRC=/qlbm/

# 8. Expose the port the app will run on
EXPOSE 7860

# 9. Healthcheck (good practice for hosting platforms)
HEALTHCHECK --interval=30s --timeout=10s --start-period=40s --retries=3 \
  CMD wget --no-verbose --tries=1 --spider http://localhost:${PORT:-7860}/ || exit 1

# 10. Start Command
# This command does two things:
# a) Starts the X Virtual FrameBuffer (Xvfb) in the background (&) on display :99
# b) 'exec' runs your app. Using 'exec' is important as it makes the Python
#    process the main one, which properly handles signals (like stopping the container).
#    '--host 0.0.0.0' is ESSENTIAL to make the server accessible from outside the container.
CMD ["sh", "-c", "Xvfb :99 -screen 0 1024x768x24 >/dev/null 2>&1 & nginx && exec python3 app.py --server --host ${APP_HOST:-127.0.0.1} --port ${APP_PORT:-8700}"]