docker port mapping using docker-gen and letsencrypt-companion - docker

Question

i have several flask applications which i want to run on a server as separate docker containers. on the server i already have several websites running with a reverse proxy and the letsencrypt-nginx-proxy-companion. unfortunately i can't get the containers to run. I think it is because of the port mapping. When I start the containers on port 80, I get the following error message "[ERROR] Can't connect to ('', 80)" from gunicorn. On all other ports it starts successfully, but then I can't access it from outside.
what am I doing wrong?
docker-compose.yml
version: '3'
services:
db:
image: "mysql/mysql-server:5.7"
env_file: .env-mysql
restart: always
app:
build: .
env_file: .env
expose:
- "8001"
environment:
- VIRTUAL_HOST:example.com
- VIRTUAL_PORT:'8001'
- LETSENCRYPT_HOST:example.com
- LETSENCRYPT_EMAIL:foo#example.com
links:
- db:dbserver
restart: always
networks:
default:
external:
name: nginx-proxy
Dockerfile
FROM python:3.6-alpine
ARG CONTAINER_USER='flask-user'
ENV FLASK_APP run.py
ENV FLASK_CONFIG docker
RUN adduser -D ${CONTAINER_USER}
USER ${CONTAINER_USER}
WORKDIR /home/${CONTAINER_USER}
COPY requirements requirements
RUN python -m venv venv
RUN venv/bin/pip install -r requirements/docker.txt
COPY app app
COPY migrations migrations
COPY run.py config.py entrypoint.sh ./
# runtime configuration
EXPOSE 8001
ENTRYPOINT ["./entrypoint.sh"]
entrypoint.sh
#!/bin/sh
source venv/bin/activate
flask deploy
exec gunicorn -b :8001 --access-logfile - --error-logfile - run:app
reverse-proxy/docker-compose.yml
version: '3'
services:
nginx:
image: nginx
labels:
com.github.jrcs.letsencrypt_nginx_proxy_companion.nginx_proxy: "true"
container_name: nginx
restart: always
ports:
- "80:80"
- "443:443"
volumes:
- /srv/www/nginx-proxy/conf.d:/etc/nginx/conf.d
- /srv/www/nginx-proxy/vhost.d:/etc/nginx/vhost.d
- /srv/www/nginx-proxy/html:/usr/share/nginx/html
- /srv/www/nginx-proxy/certs:/etc/nginx/certs:ro
nginx-gen:
image: jwilder/docker-gen
command: -notify-sighup nginx -watch -wait 5s:30s /etc/docker-gen/templates/nginx.tmpl /etc/nginx/conf.d/default.conf
container_name: nginx-gen
restart: always
volumes:
- /srv/www/nginx-proxy/conf.d:/etc/nginx/conf.d
- /srv/www/nginx-proxy/vhost.d:/etc/nginx/vhost.d
- /srv/www/nginx-proxy/html:/usr/share/nginx/html
- /srv/www/nginx-proxy/certs:/etc/nginx/certs:ro
- /var/run/docker.sock:/tmp/docker.sock:ro
- /srv/www/nginx-proxy/nginx.tmpl:/etc/docker-gen/templates/nginx.tmpl:ro
nginx-letsencrypt:
image: jrcs/letsencrypt-nginx-proxy-companion
container_name: nginx-letsencrypt
restart: always
volumes:
- /srv/www/nginx-proxy/conf.d:/etc/nginx/conf.d
- /srv/www/nginx-proxy/vhost.d:/etc/nginx/vhost.d
- /srv/www/nginx-proxy/html:/usr/share/nginx/html
- /srv/www/nginx-proxy/certs:/etc/nginx/certs:rw
- /var/run/docker.sock:/var/run/docker.sock:ro
environment:
NGINX_DOCKER_GEN_CONTAINER: "nginx-gen"
NGINX_PROXY_CONTAINER: "nginx"
DEBUG: "true"
networks:
default:
external:
name: nginx-proxy