How to configure nginx X-Forwarded-Port to be the originally request port

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I am using nginx in a standard reverse proxy scenario, to pass all requests to /auth to another host, however I'm trying to use non-standard ports.

My end goal is to have the X-Forwarded-Port header set to the port that the request comes in on.

Here is my location block in nginx.conf:

location /auth/ {
    proxy_pass       http://otherhost:8090;
    proxy_set_header Host $host;
    proxy_set_header X-Real-IP $remote_addr;
    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    proxy_set_header X-Forwarded-Proto $scheme;
    proxy_set_header X-Forwarded-Host $host;
    proxy_set_header X-Forwarded-Port <VAR>;
}

This nginx is running in a docker container, that is configured to forward requests from 8085 into 80 in the container, such that the nginx process is listening on 80:

0.0.0.0:8085->80/tcp

When I hit the URL:

http://localhost:8085/auth/

I am correctly redirected to http://otherhost:8090, but the X-Forwarded-Port header is missing or wrong.

Where I have <VAR> in the original block, I have tried the following:

  • $server_port - This is the port nginx is listening on (80), not the request port.

  • $pass_port - Seems to be null in my setup, so nginx drops the header.

  • $http_port - This is a random port per request.

  • $remote_port - This is a random port per request.

I can change my config at deploy time to hardcode to the known port of incoming requests, but ideally I would be able to change the front port without any change to the nginx config.

I've scoured the nginx variable list but can't find anything like $request_port. Is there any way for me to achieve my intent?

nginx-reverse-proxy x-forwarded-for docker reverse-proxy nginx
5 Answers

The only workaround I've found is to use a map rule to get the port from the http_host variable e.g.

    map $http_host $port {
      default 80;
      "~^[^\:]+:(?<p>\d+)$" $p;
    }
user_3959210

This is a just rough idea to write Nginx conf, but I am sure this can help you in redirection

server {    
    listen 80;  
    server_name host.docker.internal;   

    # By default land on localhost:80 to root so in root we copied UI build to the ngnix html dir.
    # have a look to docker-compose uiapp service.
    location / {    
            root   /usr/share/nginx/html;   
            index  index.html index.htm;    
    }   

   # after location add filter, from which every endpoint starts with or comes in endpoint 
   # so that ngnix can capture the URL and reroute it.
   # like /backend/getUserInfo/<UserId> 
   # In above example /backend is that filter which will be captured by Ngnix and reroute the flow.
    location /backend { 
        proxy_set_header X-Forwarded-Host $host;    
        proxy_set_header X-Forwarded-Server $host;  
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        #proxy_pass http://<ContainerName>:<PortNumber>; 
        # In our case Container name is as we setup in docker-compose `beservice` and port 8080
        proxy_pass http://beservice:8080;   
    }   
}

For more details you can have a look at this project

https://github.com/dupinder/NgnixDockerizedDevEnv

user_51086950

Inside from container you cannot access the outer config. And nginx doesn't support using environment variables inside most configuration blocks.

But if you use poco you can define your ports, paths, etc in a simple env file. These definition used by docker-compose configuration or env variable too. For example

yourconfig.env

PROJECT_HOME=..
MAGIC_DOCKER_PORT=8085

poco.yml file (main config to your project, define plans)

version: '3.0'
maintainer: "youremail@yourdomain.com"

environment:
  include: docker/conf/yourconfig.env

plan:
  live:
    description: "your plan to run live"
    docker-compose-file:
      - docker/dc-proxy.yml
      - docker/dc-other-service.yml
# you can define other plans to run local/dev env

and in docker/dc-proxy.yml compose file (relevant part):

version: '3'
services:
  proxy:
    image: nginx:alpine
    env_file: conf/yourconfig.env
    ports:
      - ${MAGIC_DOCKER_PORT}:80
    command: /bin/sh -c "envsubst < /etc/nginx/conf.d/mysite.template > /etc/nginx/conf.d/default.conf && nginx -g 'daemon off;'"

and at last your config template relevant part from /etc/nginx/conf.d/mysite.template

listen ${MAGIC_DOCKER_PORT};
...
  location /auth/ {
    ...
    proxy_set_header X-Forwarded-Port ${MAGIC_DOCKER_PORT};
    ...
  }

I use the following folder structure to organize files. It is not mandatory, but easy to use for me because my every project structure are same.

/
  docker                <- all of docker related files here
    conf                <- env files, service configs, etc
    scripts             <- shell scripts which used by containers
    dc-*.yml            <- separate all services into single compose files
  poco.yml              <- main config, "start here" point
  project-related-files <- separated by each service

Explanation

Define a key-value pair in .env file. This is used by poco for create docker-compose files, and it used to create environment variable in nginx container. After that use envsubst to fill out nginx config template, and at last starts nginx service

user_8519570

I used this:

map $http_x_forwarded_port $my_forwarded_port {
    default $remote_port;
    "~^(.*)$" $1;
}

All headers are set in variables in nginx, prefixed with http. I.e if you have origin = domain.com in header, you can use $http_origin to get "domain.com". So my code sets $my_forwarded_port to the forwarded port if it is set, otherwise to $remote_port

user_13830290

Strange that this hasn't been answered yet, but the answer is

proxy_set_header X-Forwarded-Port $server_port;
user_8131920
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