Improve Dockerfile to eliminate root user warnings and use virtual environment for dependencies

Dockerfile

@@ -11,27 +11,41 @@ RUN apt-get update && apt-get install -y \
     gcc \
     && rm -rf /var/lib/apt/lists/*
 
-# Copy requirements and install Python dependencies
+# Create a non-root user and group for building
+RUN groupadd --gid 1001 builder && \
+    useradd --uid 1001 --gid builder --shell /bin/bash --create-home builder
+
+# Switch to builder user for dependency installation
+USER builder
+WORKDIR /home/builder
+
+# Copy requirements and install Python dependencies in a virtual environment
 COPY src/server/requirements.txt .
-RUN pip install --no-cache-dir -r requirements.txt
+RUN python -m venv /home/builder/venv && \
+    /home/builder/venv/bin/pip install --no-cache-dir -r requirements.txt
 
 # Production stage
 FROM python:3.9-slim
 
+# Create a non-root user and group
+RUN groupadd --gid 1001 appuser && \
+    useradd --uid 1001 --gid appuser --shell /bin/bash --create-home appuser
+
 # Set working directory
 WORKDIR /app
 
-# Copy Python dependencies from builder stage
-COPY --from=builder /usr/local/lib/python3.9/site-packages /usr/local/lib/python3.9/site-packages
+# Copy Python dependencies from builder stage (virtual environment)
+COPY --from=builder /home/builder/venv /app/venv
 
 # Copy application code
-COPY src/server/ .
+COPY --chown=appuser:appuser src/server/ .
 
 # Copy website files
-COPY src/website/ website/
+COPY --chown=appuser:appuser src/website/ website/
 
 # Create directory for cache if it doesn't exist
-RUN mkdir -p website/cache
+RUN mkdir -p website/cache && \
+    chown -R appuser:appuser website/cache
 
 # Expose port
 EXPOSE 6006
@@ -39,6 +53,11 @@ EXPOSE 6006
 # Set environment variables
 ENV FLASK_APP=app.py
 ENV FLASK_ENV=production
+ENV USER=appuser
+ENV PATH=/app/venv/bin:$PATH
+
+# Switch to non-root user
+USER appuser
 
 # Health check
 HEALTHCHECK --interval=30s --timeout=30s --start-period=5s --retries=3 \