Dockerfile.prod

# Dockerfile.prod — Optimized Production Image for Tools
# Purpose: Minimal, secure production image with strict layer separation
# Usage: docker build -f Dockerfile.prod -t tools:prod .
# Image size target: < 500MB
# Runtime: docker run -e FLASK_ENV=production tools:prod

# Stage 1: Builder
# Compile dependencies and build wheels to minimize final image size
FROM python:3.11-slim as builder

ENV PYTHONUNBUFFERED=1 \
    PYTHONDONTWRITEBYTECODE=1 \
    PIP_NO_CACHE_DIR=1 \
    PIP_DISABLE_PIP_VERSION_CHECK=1

WORKDIR /build

# Install build dependencies
RUN apt-get update && apt-get install -y --no-install-recommends \
    build-essential \
    libffi-dev \
    libssl-dev \
    libjpeg-dev \
    zlib1g-dev \
    && rm -rf /var/lib/apt/lists/*

# Copy dependency and source files needed for package metadata and wheel builds
COPY requirements.txt pyproject.toml setup.py ./
COPY src/ ./src/

# Create wheels directory
RUN mkdir -p /build/wheels

# Build wheels for dependencies and the application package.
RUN pip install --upgrade pip setuptools wheel && \
    pip wheel --no-cache-dir --wheel-dir /build/wheels -r requirements.txt && \
    pip wheel --no-cache-dir --no-deps --wheel-dir /build/wheels ".[all]" && \
    rm -rf /build/setup.py /build/pyproject.toml

# Stage 2: Runtime
# Minimal final image with only runtime dependencies
FROM python:3.11-slim

ENV PYTHONUNBUFFERED=1 \
    PYTHONDONTWRITEBYTECODE=1 \
    PIP_NO_CACHE_DIR=1 \
    PIP_DISABLE_PIP_VERSION_CHECK=1 \
    FLASK_ENV=production \
    FLASK_APP=web_applications.calculator.webapp \
    LANG=en_US.UTF-8 \
    LC_ALL=en_US.UTF-8

WORKDIR /app

# Install minimal runtime dependencies
RUN apt-get update && apt-get install -y --no-install-recommends \
    ca-certificates \
    libffi8 \
    libssl3 \
    libjpeg62-turbo \
    zlib1g \
    && rm -rf /var/lib/apt/lists/*

# Create non-root user
RUN useradd -m -s /bin/bash appuser

# Copy wheels from builder
COPY --from=builder /build/wheels /tmp/wheels

# Install wheels (no build step needed)
RUN pip install --upgrade pip && \
    pip install --no-cache-dir --no-index --find-links /tmp/wheels ud-tools && \
    rm -rf /tmp/wheels

# Copy only source code and necessary files
COPY --chown=appuser:appuser src/ ./src/
COPY --chown=appuser:appuser setup.py pyproject.toml ./
COPY --chown=appuser:appuser .env.example ./.env.example

# Switch to non-root user
USER appuser

# Health check
HEALTHCHECK --interval=30s --timeout=10s --start-period=5s --retries=3 \
    CMD python3 -c "import urllib.request; urllib.request.urlopen('http://localhost:5000/api/health', timeout=5).read()" || exit 1

# Expose Flask default port
EXPOSE 5000

# Run Flask app
CMD ["flask", "run", "--host=0.0.0.0"]