Update Dockerfile

Dockerfile

@@ -1,11 +1,31 @@
+# Dockerfile to create a secure and minimal container image for the Metis binary.
+
+# Base stage: Use a minimal Debian image
 FROM --platform=linux/amd64 debian:bookworm-slim
 
-RUN apt-get update && apt-get install unzip openssl ca-certificates -y
+# Set the working directory for subsequent instructions
+WORKDIR /app
+
+# Install necessary dependencies (unzip for extraction, openssl/ca-certificates for HTTPS/TLS).
+# The apt cache is immediately cleaned to keep the final image size minimal.
+RUN apt-get update \
+    && apt-get install -y --no-install-recommends unzip openssl ca-certificates \
+    && rm -rf /var/lib/apt/lists/*
+
+# Copy the binary zip file into the container
 COPY ./metis-binary-x86_64-unknown-linux-gnu.zip ./metis-binary-x86_64-unknown-linux-gnu.zip
-RUN unzip metis-binary-x86_64-unknown-linux-gnu.zip
-RUN rm metis-binary-x86_64-unknown-linux-gnu.zip
-RUN chmod +x metis-binary
 
+# Combine extraction, cleanup, and permission setting into a single layer for efficiency
+RUN unzip metis-binary-x86_64-unknown-linux-gnu.zip \
+    && rm metis-binary-x86_64-unknown-linux-gnu.zip \
+    && chmod +x metis-binary
+
+# Create a non-root user and switch to it for running the application, enhancing security
+RUN useradd --no-create-home --shell /bin/false metisuser
+USER metisuser
+
+# Set environment variable for Rust logging verbosity
 ENV RUST_LOG=info
 
+# Define the default command to execute the binary when the container starts
 CMD ["./metis-binary"]