--dns-opt  A key-value pair representing a DNS option and its value. See your operating system’s documentation for resolv.conf for valid options.

services:
  mysql:
    image: mysql:5.7
    environment:
      MYSQL_DATABASE: 'main'
      MYSQL_USER: 'main'

  app:
    build:
      context: .
      dockerfile: Dockerfile-app
    links:
     - mysql
    depends_on:
     - mysql

upstream gitlab {
 server 192.168.100.17;
}


server {
    listen 80;
    server_name gitlab.by www.gitlab.by;
    client_max_body_size 3200m;
    location / {
        proxy_pass http://gitlab;
    }

}