From 9391e6b697e9f50ccbad9f65d6e7d30446046623 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Gre=CC=81goire=20Compagnon?= <obeone@obeone.org>
Date: Thu, 7 Mar 2024 11:45:50 +0100
Subject: [PATCH] chore(Dockerfile): improve caching strategy for dependency
 installation

---
 Dockerfile | 49 +++++++++++++++++++++++++------------------------
 1 file changed, 25 insertions(+), 24 deletions(-)

diff --git a/Dockerfile b/Dockerfile
index 335fa88..74228ac 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -3,14 +3,18 @@
 
 FROM python:3.12 as builder
 
-# Remove docker clean process
-RUN rm /etc/apt/apt.conf.d/docker-clean
-
-# Set non interactive mode
+# Set non-interactive mode
 ENV DEBIAN_FRONTEND=noninteractive
 
-# Update and install dependencies
-RUN --mount=type=cache,target=/var/cache/apt --mount=type=cache,target=/var/lib/apt \
+# Prevent docker from cleaning up the apt cache
+RUN rm -f /etc/apt/apt.conf.d/docker-clean
+
+# Define ARG for platform-specific cache separation
+ARG TARGETPLATFORM
+
+# Update and install dependencies with cache separated by architecture
+RUN --mount=type=cache,target=/var/cache/apt,id=apt-cache-${TARGETPLATFORM} \
+    --mount=type=cache,target=/var/lib/apt,id=apt-lib-${TARGETPLATFORM} \
     apt-get update && \
     apt-get install -y libxml2-dev libxslt-dev
 
@@ -18,46 +22,43 @@ WORKDIR /app
 
 COPY requirements.txt .
 
-RUN --mount=type=cache,target=/root/.cache \
+# Use pip cache to speed up builds
+RUN --mount=type=cache,target=/root/.cache/pip \
     pip install -r requirements.txt -t packages
 
-# Start from a lightweight Python 3.12 image to ensure a small final image size
+# Start from a slim Python 3.12 image for a small final image size
 FROM python:3.12-slim as final
 
+# Set non-interactive mode
+ENV DEBIAN_FRONTEND=noninteractive
 
-# Copy built packages from the previous stage (Do it first to force that the building of this stage wait for the previous stage to finish and avoid a race condition)
-COPY --from=builder /app/packages /app/packages
+# Prevent docker from cleaning up the apt cache in the final image
+RUN rm -f /etc/apt/apt.conf.d/docker-clean
 
-# Remove docker clean process
-RUN rm /etc/apt/apt.conf.d/docker-clean
+ARG TARGETPLATFORM
 
-# Set non interactive mode
-ENV DEBIAN_FRONTEND=noninteractive
+# Copy built packages from the previous stage
+COPY --from=builder /app/packages /app/packages
 
-# Update and install dependencies
-RUN --mount=type=cache,target=/var/cache/apt --mount=type=cache,target=/var/lib/apt \
+# Update and install runtime dependencies if necessary, with cache separated by architecture
+RUN --mount=type=cache,target=/var/cache/apt,id=apt-cache-${TARGETPLATFORM} \
+    --mount=type=cache,target=/var/lib/apt,id=apt-lib-${TARGETPLATFORM} \
     apt-get update && \
     apt-get install -y libxml2 libxslt1.1
 
-# Set the working directory inside the container to /app
 WORKDIR /app
 
 ENV PYTHONPATH=/app/packages:$PYTHONPATH
 
-# Copy the requirements.txt file into the working directory
 COPY requirements.txt .
 
-# Install dependencies from requirements.txt using pip
-# Utilize Docker's cache mount feature to speed up builds by caching pip's cache directory
-RUN --mount=type=cache,target=/root/.cache \
+# Install dependencies from requirements.txt using pip and cache
+RUN --mount=type=cache,target=/root/.cache/pip \
     pip install -r requirements.txt
 
 # Copy the rest of the application's source code into the working directory
 COPY . .
 
-# Declare a volume at /app/cache to allow for caching or persisting data outside of the container
 VOLUME [ "/app/cache"]
 
-# Set the container's entrypoint to run the main Python application
 ENTRYPOINT [ "python", "main.py" ]
-