nginx reverse proxy on docker - problem with setup custom ip for each domain

Question

I an have nginx reverse proxy running in a docker container. On the host server I have a service failover ip.

I want set for each domain on the nginx server to a custom ip, beacause at the moment all domains are using the main ip of my server.

How I can do that?

Answer 1

First, I would argue that what you have right now is the most common configuration: your reverse proxy (nginx/traefik/haproxy/etc) listens on a single address and then routing requests to appropriate backend hosts by name. Configuring a separate external ip for each domain adds a level of complexity that may not be necessary.

However, if you really want to do that, start by adding multiple ip addresses to your host. For example, on my host, I have:

$ ip addr show eth0
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    altname eno2
    altname enp0s31f6
    inet 192.168.1.200/24 brd 192.168.1.255 scope global noprefixroute eth0
       valid_lft forever preferred_lft forever
    inet 192.168.1.201/24 brd 192.168.1.255 scope global secondary noprefixroute eth0
       valid_lft forever preferred_lft forever
    inet 192.168.1.202/24 brd 192.168.1.255 scope global secondary noprefixroute eth0
       valid_lft forever preferred_lft forever
    inet 192.168.1.175/24 brd 192.168.1.255 scope global secondary dynamic noprefixroute eth0
       valid_lft 55548sec preferred_lft 55548sec

I have a sample configuration in which I am running nginx as the frontend with two different backends (named backend1 and backend2).

I'm going to configure nginx so that connections to 192.168.1.201 go to backend1 and connections to 192.168.1.202 go to backend2. We do that by:

1. Having nginx listen on multiple ports (one port for each backend), and then
2. Publishing these ports on different ip addresses

We start with the nginx configuration:

server {
    listen       8000;
    server_name  localhost;

    location / {
        proxy_pass http://backend1/;
    }
}

server {
    listen       8001;
    server_name  localhost;

    location / {
        proxy_pass http://backend2/;
    }
}

This maps connections on port 8000 to backend1 and connections on port 8001 to backend2. To expose these on port 80 on different host addresses, we can create a docker-compose.yaml like this:

services:
  frontend:
    image: docker.io/nginx:mainline
    volumes:
      - ./nginx/default.conf:/etc/nginx/conf.d/default.conf
    ports:
      - 192.168.1.201:80:8000
      - 192.168.1.202:80:8001

  backend1:
    image: docker.io/containous/whoami:latest

  backend2:
    image: docker.io/containous/whoami:latest

This means that connections to http://192.168.1.201 will get mapped to port 8000, and hence to backend1, while connections to http://192.168.1.202 will get mapped to port 8001, and hence to backend2.

---

After running docker-compose up, I can confirm this configuration:

$ curl -s 192.168.1.201 | grep Host:
Host: backend1
$ curl -s 192.168.1.202 | grep Host:
Host: backend2