Add entrypoint script

Dockerfile

@@ -8,8 +8,7 @@ COPY requirements.txt ./
 RUN pip install --no-cache-dir -r requirements.txt
 
 COPY . .
-RUN python manage.py collectstatic
 
 EXPOSE 8000
 
-ENTRYPOINT ["gunicorn", "shiftregister.wsgi", "-b", "0.0.0.0:8000"]
+ENTRYPOINT ["/opt/shiftregister/entrypoint.sh"]

entrypoint.sh

@@ -0,0 +1,20 @@
+#!/bin/sh
+
+set -e
+
+ROLE="${ROLE:-app}"
+
+case "$ROLE" in
+	app)
+		python manage.py collectstatic
+		python manage.py migrate
+		gunicorn shiftregister.wsgi -b 0.0.0.0:8000 "$@"
+		;;
+	worker)
+		celery -A shiftregister worker -B
+		;;
+	*)
+		echo 'unknown role "'"$ROLE"'"' >&2
+		sleep 1
+		;;
+esac