Move from Alpine-bundled uwsgi to pip-installed and compiled uwsgi.

Alpine ships uWSGI linked against the most recent Python version,
i. e. currently python3.9. The current deployment uses python3.8
though, so whenever our Python version diverges from Alpine's
stable version, uWSGI will break (aka fail to run the parser).

Switching to installing uWSGI via pip into the pipenv will make sure
that the uWSGI Python module's version will always fit our venv.

Dockerfile

@@ -1,19 +1,26 @@
 ARG DEPLOY_DIR=/opt/om-parser-stw-potsdam-v2
+ARG USERNAME=flaskd
 ARG LISTEN_PORT=3080
 
-# Build & test container
-FROM python:3.8-alpine as buildsys
-ARG DEPLOY_DIR
 
-# Install required dependencies
-RUN apk add make
+### Shared base container
+FROM python:3.8-alpine as basesys
+ARG DEPLOY_DIR
+ARG USERNAME
+
+# Install dependencies
 RUN pip install pipenv
 
 # Add app user
-RUN adduser -D flaskd
+RUN adduser -D ${USERNAME}
 
 # Create app folder
 RUN mkdir -p ${DEPLOY_DIR}
+
+# Enable local venv
+ENV PIPENV_VENV_IN_PROJECT=1
+
+# Switch to app folder
 WORKDIR ${DEPLOY_DIR}
 
 # Copy app folder contents
@@ -24,44 +31,57 @@ COPY Pipfile .
 COPY Pipfile.lock .
 
 # Apply app user to app folder
-RUN chown -R flaskd:flaskd .
+RUN chown -R ${USERNAME} .
 
 # Prepare environment
-USER flaskd
+USER ${USERNAME}
+
+
+### Build & test container
+FROM basesys as buildsys
+ARG DEPLOY_DIR
+ARG USERNAME
+
+# Install required build dependencies
+USER root
+RUN apk add make gcc musl-dev linux-headers python3-dev
 
 # Install environment
+USER ${USERNAME}
 RUN pipenv install --dev
 
 # Run tests
 RUN make test
 
-
-# Executable container
-
-FROM python:3.8-alpine
-
-ARG DEPLOY_DIR
-ARG LISTEN_PORT
-
-ENV LISTEN_PORT=$LISTEN_PORT
-ENV LISTEN=0.0.0.0:$LISTEN_PORT
-
-RUN apk add --no-cache uwsgi uwsgi-python curl
-RUN pip install pipenv
-RUN adduser -D flaskd
-
-COPY --from=buildsys ${DEPLOY_DIR} ${DEPLOY_DIR}
-
-WORKDIR ${DEPLOY_DIR}
+# Clean up test environment
+RUN rm -rf .venv
 RUN rm -rf ./tests ./Makefile
-RUN chown -R flaskd:flaskd .
 
-USER flaskd
-
-ENV PIPENV_VENV_IN_PROJECT=1
+# Install production environment
 RUN pipenv install --deploy
 
-EXPOSE $LISTEN_PORT
+
+### Production container
+
+FROM basesys
+ARG DEPLOY_DIR
+ARG LISTEN_PORT
+ARG USERNAME
+
+# Install dependencies
+USER root
+RUN apk add curl
+
+# Copy built app
+USER ${USERNAME}
+COPY --from=buildsys ${DEPLOY_DIR}/.venv ${DEPLOY_DIR}/.venv
+WORKDIR ${DEPLOY_DIR}
+
+# Prepare runtime environment variables
+ENV LISTEN_PORT=${LISTEN_PORT}
+ENV LISTEN=0.0.0.0:${LISTEN_PORT}
+
+EXPOSE ${LISTEN_PORT}
 CMD pipenv run uwsgi --master --http11-socket $LISTEN --plugins python --protocol uwsgi --wsgi stw_potsdam.views:app --virtualenv ./.venv
 
 HEALTHCHECK --interval=15s --timeout=3s CMD curl -f http://127.0.0.1:$LISTEN_PORT/health_check || exit 1