Dockerfile

# ==========================================
# Stage 1: Build dependencies
# ==========================================
FROM python:3.11-slim AS builder

WORKDIR /app

ENV PYTHONDONTWRITEBYTECODE=1 \
    PYTHONUNBUFFERED=1

# Install build dependencies (required for compiling wheel files like psycopg/cryptography packages)
RUN apt-get update \
    && apt-get install --no-install-recommends -y build-essential \
    && rm -rf /var/lib/apt/lists/*

# Copy requirements and compile them to wheels
COPY requirements.txt .
RUN pip install --no-cache-dir --upgrade pip \
    && pip wheel --no-cache-dir --wheel-dir /app/wheels -r requirements.txt


# ==========================================
# Stage 2: Runtime image
# ==========================================
FROM python:3.11-slim AS runtime

WORKDIR /app

ENV PYTHONDONTWRITEBYTECODE=1 \
    PYTHONUNBUFFERED=1 \
    FLASK_DEBUG=0 \
    PORT=8000 \
    WEB_CONCURRENCY=1

# Install runtime utilities only (curl is needed for the container healthcheck)
RUN apt-get update \
    && apt-get install --no-install-recommends -y curl \
    && rm -rf /var/lib/apt/lists/*

# Copy compiled wheels from builder stage and install them instantly without compiling
COPY --from=builder /app/wheels /wheels
COPY --from=builder /app/requirements.txt .
RUN pip install --no-cache-dir --upgrade pip \
    && pip install --no-cache-dir --no-index --find-links=/wheels -r requirements.txt \
    && rm -rf /wheels

# Copy application files
COPY . .

# Set up non-root user for security (principle of least privilege)
RUN addgroup --system appuser \
    && adduser --system --ingroup appuser appuser \
    && chown -R appuser:appuser /app

USER appuser

EXPOSE 8000

# Continuous health monitoring of the application using the Flask diagnostic endpoint
HEALTHCHECK --interval=30s --timeout=5s --start-period=30s --retries=3 \
    CMD curl -f http://localhost:$PORT/healthz || exit 1

CMD ["sh", "-c", "exec gunicorn 'switchbot_dashboard:create_app()' --config gunicorn.conf.py"]