Enable Heroku to pass $PORT to Docker

Dockerfile

@@ -22,9 +22,9 @@ WORKDIR /doccano
 
 ENV DEBUG="True"
 ENV SECRET_KEY="change-me-in-production"
-ENV BIND="0.0.0.0:80"
+ENV PORT="80"
 ENV WORKERS="2"
 
-EXPOSE 80
+EXPOSE ${PORT}
 
 CMD ["/doccano/tools/run.sh"]

tools/run.sh

@@ -6,4 +6,4 @@ if [[ ! -d "app/staticfiles" ]]; then python app/manage.py collectstatic --noinp
 
 python app/manage.py wait_for_db
 python app/manage.py migrate
-gunicorn --bind="${BIND:-127.0.0.1:8000}" --workers="${WORKERS:-1}" --pythonpath=app app.wsgi
+gunicorn --bind="0.0.0.0:${PORT:-8000}" --workers="${WORKERS:-1}" --pythonpath=app app.wsgi