Running redmine under the NGINX reverse proxy on Docker.

config.ru

require ::File.expand_path('../config/environment',  __FILE__)
map ENV['RAILS_RELATIVE_URL_ROOT'] || '/' do
  run Rails.application
end

default.conf

upstream redmine_back {
  server redmine:3000;
}
server {
  location /redmine/ {
    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    proxy_set_header Host $http_host;
    proxy_set_header X-Real-IP $host;
    proxy_set_header X-Forwarded-Proto $scheme;
    proxy_set_header X-Forwarded-Server $host;
    proxy_set_header X-Forwarded-Host $host;
    
    proxy_pass http://redmine_back/redmine/;
    proxy_redirect default;
  }
}

docker-compose.yml

version: '3'
services:
  redmine:
    build:
      context: ./redmine
      dockerfile: Dockerfile
    environment: 
      RAILS_RELATIVE_URL_ROOT: '/redmine'
  web-proxy:
    image: nginx:1.17-alpine
    volumes: 
      - ./web-proxy/default.conf:/etc/nginx/conf.d/default.conf
    links:
      - redmine
    ports:
      - 80:80

Dockerfile

FROM redmine:4.0.5-alpine

COPY --chown=redmine:redmine config.ru config.ru