FROM python:3.11-slim

# Set working directory
WORKDIR /app

# Copy requirements first for better caching
COPY requirements.txt .

# Install dependencies
RUN pip install --no-cache-dir -r requirements.txt

# Copy application
COPY dyndns.py .

# Make script executable
RUN chmod +x dyndns.py

# Run as non-root user
RUN useradd -m -u 1000 dyndns && \
    chown -R dyndns:dyndns /app

USER dyndns

# Health check
HEALTHCHECK --interval=5m --timeout=10s --start-period=30s --retries=3 \
    CMD python -c "import sys; sys.exit(0)"

# Run the application
CMD ["python", "-u", "dyndns.py"]