nginx proxy_pass proxy_set_header of proxy host

MrPHP

4/11/24, 8:03 AM

Using NGINX as a reverse proxy, I want to tag which load balancer/proxy the request can in on, and pass that to the end app servers...

For example, we have 2 ingress connections, using round-robin DNS to 3 load balancers,

so, connection one has 3 pubic IP's and connection two has 3 IP's. each pair points to a load balancer and they're using proxy pass upstream to send traffic to the 10 web/app servers.

I want to tag which of the 3 LB's the request comes in on, I'd love to tag it based on the connection too, if you know how.


upstream web_cluster {
    random;
    # web server ip addresses x 10
}

location / {
    proxy_pass                      http://web_cluser;
    proxy_set_header                Proxy $proxy_server_host_name; // here
    proxy_set_header                Route $proxy_server_public_ip; // here
    proxy_pass_request_headers      on;
}

The servers are all deployed via Ansible scripts, so I wouldn't be able to hard-code server names into the proxy_set_header options.

Thanks

615

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nginx

nginx-reverse-proxy

Score:1

Server

Saxtheowl

4/11/24, 4:36 PM

To tag all this we could change your configuration file to use the map directive to map the remote IP address to the corresponding load balancer name, and the $proxy_host variable to set the Proxy-Host header.

upstream web_cluster {
    server 10.0.0.1;
    server 10.0.0.2;
    server 10.0.0.3;
    # add more servers here as needed
}

map $remote_addr $proxy_host {
    192.168.1.1  "lb1";
    192.168.1.2  "lb2";
    192.168.1.3  "lb3";
    # add more mappings here as needed
}

server {
    listen 80;
    server_name example.com;

    location / {
        proxy_pass http://web_cluster;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header Proxy-Host $proxy_host;
    }
}

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