Question

I am using two system (both are Nginx load balancer and one act as backup).

I want to add and use few HTTP custom headers.

Below is my code for both:

upstream upstream0 {
    #list of upstream servers
    server backend:80;
    server backup_load_balancer:777 backup;
    #healthcheck
}

server {
    listen 80;
    #Add custom header about the port and protocol  (http or https)
    server_name _;

    location / {
        # is included since links are not allowed in the post
        proxy_pass "http://upstream0;"
    }
}

Backup system

server {
    listen 777;
    server_name _;
    #doing some other extra stuff
    #use port and protocol to direct
}

How can I achieve that?

Answer 1

To add a header, add the add_header declaration to either the location block or the server block:

server {
   add_header X-server-header "my server header content!";
   location /specific-location {
       add_header X-location-header "my specific-location header content!";
   }
}

An add_header declaration within a location block will override the same add_header declaration in the outer server block.
e.g. if location contained add_header X-server-header ... that would override the outer declaration for that path location.

Obviously, replace the values with what you want to add. And that’s all there is to it.