Multi-stage build oh my!

Dockerfile

@@ -1,26 +1,32 @@
-FROM python:3.8-alpine
+FROM python:3.8-alpine as build
 
 RUN apk add gettext git gcc python3-dev musl-dev \
     libffi-dev zlib-dev jpeg-dev libjpeg postgresql-dev build-base \
     --virtual .build-dependencies
 
-RUN mkdir /code
+RUN mkdir -p /app/{code,venv}
-WORKDIR /code
+WORKDIR /app/code
-COPY Pipfile Pipfile.lock /code/
+COPY Pipfile Pipfile.lock /app/code/
 
-RUN pip install pipenv setuptools wheel cppy
+RUN python3 -m venv /app/venv
+RUN pip install pipenv setuptools
+ENV PATH="/app/venv/bin:$PATH" VIRTUAL_ENV="/app/venv"
+RUN pip install wheel cppy
+# Install dependencies into the virtual environment with Pipenv
+RUN pipenv install --deploy --verbose
 
-RUN pipenv install --system --deploy --verbose
+FROM python:3.8-alpine
-
-RUN apk del .build-dependencies \
- && rm -rf /var/cache/apk/* /tmp/*
 
 RUN apk add --no-cache libpq libstdc++ libjpeg
 
-COPY . /code/
+COPY . /app/code/
+WORKDIR /app/code
+
+COPY --from=build /app/venv /app/venv
+ENV PATH="/app/venv/bin:$PATH" VIRTUAL_ENV="/app/venv"
 
 CMD ["gunicorn", "--bind", "0.0.0.0:5000", "-k", "gevent", "--worker-connections", "1000", "app:app"]
 
-VOLUME /code
+VOLUME /app/code
 
 EXPOSE 5000

docker-compose.yml

@@ -6,7 +6,7 @@ services:
     image: 3wordchant/capsul-flask:latest
     build: .
     volumes:
-      - "./:/code"
+      - "./:/app/code"
     depends_on:
       - db
     ports: