Slim down production Django container

Heavily baed on Anthony Ledesma's PR (GhostManager#163), this builds the Python
wheels in a separate stage, so that the published docker image does
not have the packages for building or the source codes taking up space.

The Django image has shrunk from roughly 2gb to 400mb.

Author: ColonelThirtyTwo

compose/local/django/Dockerfile

@@ -25,7 +25,7 @@ RUN apk --no-cache add build-base curl \
 
 COPY ./requirements /requirements
 
-RUN pip install --no-cache-dir -r /requirements/local.txt
+RUN pip install --no-cache-dir -r /requirements/local.txt --no-binary psycopg2
 
 COPY ./compose/production/django/entrypoint /entrypoint
 

compose/production/django/Dockerfile

@@ -3,35 +3,41 @@ FROM node:21-alpine AS frontendbuild
 COPY ./javascript /app
 RUN --mount=type=cache,target=/root/.npm cd /app && npm ci && npm run build-frontend-prod
 
-FROM python:3.10.9-alpine3.17
-
-ENV PYTHONUNBUFFERED=1
-
-ENV PYTHONPATH="$PYTHONPATH:/app/config"
+FROM python:3.10.9-alpine3.17 AS build
 
+COPY ./requirements /requirements
 RUN \
     --mount=type=cache,target=/var/cache/apk/ \
-    --mount=type=cache,target=/root/.cache/pip \
     apk add build-base curl \
     # psycopg2 dependencies
     && apk add --virtual build-deps gcc python3-dev musl-dev \
-    && apk add postgresql-dev \
+    && apk add libpq-dev \
     # Pillow dependencies
     && apk add jpeg-dev zlib-dev freetype-dev lcms2-dev openjpeg-dev tiff-dev tk-dev tcl-dev \
     # CFFI dependencies
     && apk add libffi-dev py-cffi \
     # XLSX dependencies
     && apk add libxml2-dev libxslt-dev \
     # Rust and Cargo required by the ``cryptography`` Python package
-    && apk add rust cargo \
-    && addgroup -S django \
-    && adduser -S -G django django \
-    && pip install -U setuptools pip
+    && apk add rust cargo
+RUN \
+    --mount=type=cache,target=/root/.cache/pip \
+    pip install wheel \
+    && pip wheel --wheel-dir=/wheels --no-binary psycopg2 -r /requirements/production.txt
 
-COPY ./requirements /requirements
+FROM python:3.10.9-alpine3.17
+
+RUN \
+  --mount=type=cache,target=/var/cache/apk/ \
+  apk add libpq
+
+RUN \
+  --mount=type=bind,target=/wheels,source=/wheels,from=build \
+  --mount=type=bind,target=/requirements,source=/requirements,from=build \
+  --mount=type=cache,target=/root/.cache/pip \
+  pip install --find-links=/wheels -r /requirements/production.txt
 
-RUN --mount=type=cache,target=/root/.cache/pip pip install -r /requirements/production.txt \
-    && rm -rf /requirements
+RUN addgroup -S django && adduser -S -G django django
 
 COPY ./compose/production/django/entrypoint /entrypoint
 

requirements/base.txt

@@ -22,6 +22,7 @@ djangorestframework==3.15.2  # https://github.com/encode/django-rest-framework
 django-health-check==3.18.3  # https://github.com/KristianOellegaard/django-health-check
 
 # Ghostwriter specific
+psycopg2==2.9.6 # https://github.com/psycopg/psycopg2
 boto3==1.35.17
 botocore==1.35.17
 beautifulsoup4==4.12.3

requirements/local.txt

@@ -3,7 +3,6 @@
 Werkzeug[watchdog]==2.3.4 # https://github.com/pallets/werkzeug
 ipdb==0.13.13  # https://github.com/gotcha/ipdb
 Sphinx==3.2.1  # https://github.com/sphinx-doc/sphinx
-psycopg2==2.9.6 --no-binary psycopg2  # https://github.com/psycopg/psycopg2
 watchgod==0.8.2  # https://github.com/samuelcolvin/watchgod
 
 # Testing

requirements/production.txt

@@ -3,7 +3,6 @@
 -r ./base.txt
 
 gunicorn==20.1.0  # https://github.com/benoitc/gunicorn
-psycopg2==2.9.3 --no-binary psycopg2  # https://github.com/psycopg/psycopg2
 Collectfast==2.2.0  # https://github.com/antonagestam/collectfast
 
 # Django