add healthcheck for http services

setup/Dockerfile

@@ -4,7 +4,7 @@ RUN mkdir -p /app
 WORKDIR /app
 
 COPY requirements.txt requirements.txt
-RUN apk add --no-cache git \
+RUN apk add --no-cache git curl \
  && pip install -r requirements.txt
 
 COPY server.py ./server.py
@@ -16,3 +16,5 @@ RUN python setup.py https://github.com/mailu/mailu /data
 EXPOSE 80/tcp
 
 CMD gunicorn -w 4 -b :80 --access-logfile - --error-logfile - --preload main:app
+
+HEALTHCHECK CMD curl -f -L http://localhost/ || exit 1