feat(docker): enhance Dockerfile with caching and comments

.dockerignore

@@ -0,0 +1,3 @@
+/.devcontainer
+/.github
+/tests

Dockerfile

@@ -1,16 +1,46 @@
-FROM python:3-slim
+# Use the Dockerfile syntax version 1.5 for enhanced features
+# syntax=docker/dockerfile:1.5
 
+# Start from a lightweight Python 3.12 image
+FROM python:3.12-slim
+
+# Set environment variables to control shell interaction and markdown formatting
+# Disable shell interaction by default (not possible in docker)
 ENV SHELL_INTERACTION=false
+
+# Disable markdown prettification by default
 ENV PRETTIFY_MARKDOWN=false
+
+# Automatically detect the operating system name
 ENV OS_NAME=auto
+
+# Automatically detect the shell name
 ENV SHELL_NAME=auto
 
+# Set the DEBIAN_FRONTEND environment variable to noninteractive to suppress prompts during package installation
+ENV DEBIAN_FRONTEND=noninteractive
+
+# Disable automatic clean-up of apt cache to retain downloaded packages
+RUN rm /etc/apt/apt.conf.d/docker-clean && \
+    echo 'Binary::apt::APT::Keep-Downloaded-Packages "true";' > /etc/apt/apt.conf.d/keep-cache
+
+# Update package lists and install the gcc compiler while caching the apt data
+RUN --mount=type=cache,target=/var/cache/apt \
+    --mount=type=cache,target=/var/lib/apt \
+    apt-get update && apt-get install -y gcc
+
+# Set the working directory to /app
 WORKDIR /app
-COPY . /app
 
-RUN apt-get update && apt-get install -y gcc
-RUN pip install --no-cache /app && mkdir -p /tmp/shell_gpt
+# Copy the current directory contents into the /app directory in the container
+COPY . .
+
+# Install Python dependencies using pip while caching the pip data
+RUN --mount=type=cache,target=/root/.cache/pip \
+    pip install /app
 
+# Define a mount point for temporary files
 VOLUME /tmp/shell_gpt
 
+# Set the default command to run when the container starts
 ENTRYPOINT ["sgpt"]