Update Dockerfile

Dockerfile

@@ -1,21 +1,46 @@
+# Start with a slim and secure Python base image
 FROM python:3.9-slim
 
-# Set the working directory to /app
+# --- Environment Variables ---
+# Prevents Python from writing .pyc files to disc
+ENV PYTHONDONTWRITEBYTECODE 1
+# Ensures Python output is sent straight to the terminal without buffering
+ENV PYTHONUNBUFFERED 1
+# Set the MPLCONFIGDIR to a writable directory to avoid matplotlib warnings
+ENV MPLCONFIGDIR /tmp/matplotlib
+
+# --- System Dependencies ---
+# First, update the package lists and install system libraries required by OpenCV.
+# Combining these into a single RUN layer reduces image size.
+# libglib2.0-0 is essential to fix the "libgthread-2.0.so.0" error.
+RUN apt-get update && \
+    apt-get install -y --no-install-recommends \
+    libgl1-mesa-glx \
+    libglib2.0-0 && \
+    # Clean up the apt cache to reduce image size
+    rm -rf /var/lib/apt/lists/*
+
+# --- Python Dependencies ---
+# Set the working directory
 WORKDIR /app
 
-# Copy the requirements file
+# Copy only the requirements file first to leverage Docker's layer caching.
+# This layer will only be re-run if requirements.txt changes.
 COPY requirements.txt .
 
-# Install the dependencies
-RUN pip install -r requirements.txt
-RUN apt-get update && apt-get install -y libgl1-mesa-glx
-RUN pip install opencv-python-headless
+# Install Python dependencies from the requirements file.
+# --no-cache-dir reduces image size.
+RUN pip install --no-cache-dir -r requirements.txt
 
-# Copy the application code
+# --- Application Code ---
+# Now, copy the rest of the application code into the container.
+# This layer will be rebuilt on code changes, but the dependencies above will not.
 COPY . .
 
-# Expose the port
+# --- Port and Command ---
+# Expose the port the application will run on
 EXPOSE 7860
 
-# Run the command to start the development server
-CMD ["uvicorn", "predict:app", "--host", "0.0.0.0", "--port", "7860"]
+# The command to run the application
+# Using a list format is the recommended way to write CMD
+CMD ["uvicorn", "predict:app", "--host", "0.0.0.0", "--port", "7860"]