Linking containers through networks OMV 7

Hi,

I am still quite new to OMV or setting up my own NAS in general but the last few months I have been working on (and struggling with) setting up docker and getting a mediaserver (Jellyfin) and cloud solution (Nextcloud) up and running via Nginx proxy manager.

The reason it took me so long is that many tutorials and guides are (slightly) outdated or do not sufficiently explain (the importance of) networking in docker and how to do that in OMV7.

So, after finally having a working setup, I want to post my setup and hopefully help someone, or get useful feedback to improve.

By default, many containers create their own network in docker. To get it to communicate with the proxy manager, they need to be in the same network.

So, for every network you want to use, you need to create it in the OMV GUI (Services -> Compose -> Networks)

In this example I created the network "dockernet" and "nextcloud-aio" with 172.20.0.0/16 en 172.18.0.0/16 subnets (Set the Gateways accordingly, driver: bridge).

In the compose files I need to make the container not create their own network, but connect to the network I created.

This example of Jellyfin shows my settings in a configuration with nginx proxy manager.

Jellyfin

---
# Date: 2025-06-01
# https://hub.docker.com/r/linuxserver/jellyfin
# https://jellyfin.org/docs/
services:
  jellyfin:
    image: lscr.io/linuxserver/jellyfin:latest
    networks:
      dockernet:
    container_name: jellyfin
    environment:
      - PUID=1002
      - PGID=1002
      - TZ=${TIME_ZONE_VALUE}
    volumes:
      - ${PATH_TO_APPDATA}/jellyfin/config:/config
      - ${PATH_TO_MEDIA}/series:/data/tvshows
      - ${PATH_TO_MEDIA}/films:/data/movies
      - ${PATH_TO_MEDIA}/muziek:/data/music
    ports:
      - 8096:8096
      - 8920:8920 #optional
    restart: unless-stopped
networks:
  dockernet:
    external: true # explanation under Nextcloud-AIO

NGINX proxy manager (NPM)

---
# Date: 2025-06-01
# https://github.com/NginxProxyManager/nginx-proxy-manager
services:
  app:
    image: jc21/nginx-proxy-manager:latest
    restart: unless-stopped
    networks:
      dockernet:
      nextcloud-aio:
    ports:
      # These ports are in format <host-port>:<container-port>
      - 80:80     # no quotes around the ports!
      - 443:443
      - 81:81
      # Add any other Stream port you want to expose
      # - 21:21
    environment:
      #Mysql/Maria connection parameters:
      DB_MYSQL_HOST: db
      DB_MYSQL_PORT: 3306
      DB_MYSQL_USER: npm
      DB_MYSQL_PASSWORD: npm
      DB_MYSQL_NAME: npm
      DISABLE_IPV6: true
    volumes:
      - ${PATH_TO_APPDATA}/nginxproxymanager/data:/data
      - ${PATH_TO_APPDATA}/nginxproxymanager/letsencrypt:/etc/letsencrypt
    depends_on:
      - db
  db:
    image: jc21/mariadb-aria:latest
    restart: unless-stopped
    networks:
      dockernet:
    environment:
      MYSQL_ROOT_PASSWORD: npm
      MYSQL_DATABASE: npm
      MYSQL_USER: npm
      MYSQL_PASSWORD: npm
      MARIADB_AUTO_UPGRADE: 1
    volumes:
      - ${PATH_TO_APPDATA}/nginxproxymanager/mysql:/var/lib/mysql
networks:
  dockernet:
    external: true
  nextcloud-aio:
    external: true

Note that I have connected NPM to two networks. Docker containers in the same docker network have all their ports to each other exposed, so I like Nextloud AIO separated from my other containers.

Nextcloud-AIO

Nextcloud-aio has a mandatory network: nextcloud-aio. Yes, the same network I created earlier, but I think it's important to configure like this. The declaration 'external: true' is to tell docker that the network is configured outside the container. I created the networks in the gui, so 'external: true' should be set here. Also in the other compose files.

In this file I used "init: true" based on the docker docs. I am not sure if it's needed, but based on https://github.com/nextcloud/a…ne/blob/main/compose.yaml it makes sense to add it.

# https://wiki.omv-extras.org/doku.php?id=omv7:docker_in_omv#examples_of_configuration_of_some_containers
# https://github.com/nextcloud/all-in-one
# For custom configuration consult - https://github.com/nextcloud/all-in-one/blob/main/compose.yaml
services:
  nextcloud-aio-mastercontainer:
    image: nextcloud/all-in-one:latest
    restart: unless-stopped
    container_name: nextcloud-aio-mastercontainer
    init: true
    networks:
      nextcloud-aio:
    volumes:
      - nextcloud_aio_mastercontainer:/mnt/docker-aio-config
      - /var/run/docker.sock:/var/run/docker.sock:ro
    ports:
      - 8080:8080
    environment:
      - NEXTCLOUD_DATADIR=${PATH_TO_NC}
      - APACHE_PORT=11000 
      - APACHE_IP_BINDING=127.0.0.1 # important for nginx to refer to 'localhost' 
      # Apache settings are needed when running behind a web server or reverse proxy, https://github.com/nextcloud/all-in-one/blob/main/compose.yaml
volumes:
  nextcloud_aio_mastercontainer:
    name: nextcloud_aio_mastercontainer
networks:
  nextcloud-aio:
    external: true

In Nginx you can refer to Nextcloud by 'localhost' as in this guide that OMV-extras links to. I think you need this setting for it:

APACHE_IP_BINDING=127.0.0.1

In my nginx proxy host config I don´t use localhost, but the (network)name (use inspect) of nextcloud, in my case: nextcloud-aio-mastercontainer. I am not sure if this Apache setting is needed in my case. By disabling it NC seems to be working fine, but I don´t exactly know what I'm messing with. And I haven´t used NC very much yet to properly test.

I hope this is useful to someone.

Thank you for everyone working on OMV!

Quote

Maybe you didn't read this? --> https://wiki.omv-extras.org/doku.php?id=omv7:docker_in_omv

probably > 50 times.

following this guide and the other guides available I couldn´t get it to work in my use case (which is pretty standard, I think).

I did however get it to work when I put NGINX and the service I want to run via NGINX in the same docker network. Following your guide I have every service running in their own network, and not being able to communicate with each other.

So I tried the nginx example in linked guide once again and leaving out the network parts from my nginx compose file, omitting the following parts:

nginx
(...)
    networks:
      dockernet:
      nextcloud-aio:
(...)
db
(...)
    networks:
      dockernet:
(...)
networks:
  dockernet:
    external: true
  nextcloud-aio:
    external: true

Now nginx and the db are in the nginxpm_default network. Alone. So no service will work through nginx.

What am I missing then? i do have the standard bridge network running, but the containers do not automatically connect to it. Apparently in your case they do, because the guide doesn´t mention docker networks or bridge networks at all.

Cheers,

Lennard.