add healthcheck for http services

docs/Dockerfile

@@ -3,7 +3,7 @@ FROM python:3-alpine
 COPY requirements.txt /requirements.txt
 
 RUN pip install -r /requirements.txt \
- && apk add --no-cache nginx \
+ && apk add --no-cache nginx curl \
  && mkdir /run/nginx
 
 COPY ./nginx.conf /etc/nginx/conf.d/default.conf
@@ -11,4 +11,8 @@ COPY . /docs
 
 RUN sphinx-build /docs /build
 
-CMD nginx -g "daemon off;"
+EXPOSE 80/tcp
+
+CMD nginx -g "daemon off;"
+
+HEALTHCHECK CMD curl -f -L http://localhost/ || exit 1