NGINX $upstream_http_name

In Nginx, the variable:

$upstream_http_<name>

is used to access a response header returned by the upstream server (backend).

So specifically:

$upstream_http_name

means:

👉 “The value of the Name HTTP response header sent by the upstream server.”

🔹 How It Works

When Nginx proxies a request (using proxy_pass, fastcgi_pass, etc.), the backend returns response headers like:

HTTP/1.1 200 OK
Content-Type: application/json
X-Request-ID: abc123
Name: my-service

You can access those headers in Nginx using:

$upstream_http_content_type
$upstream_http_x_request_id
$upstream_http_name

Rules:

• Header names are lowercased
• Dashes (-) become underscores (_)
• Prefixed with upstream_http_

🔹 Example Usage

1️⃣ Logging an upstream header

log_format custom '$remote_addr - $upstream_http_name';

access_log /var/log/nginx/access.log custom;

2️⃣ Passing upstream header to client

location / {
    proxy_pass http://backend;

    add_header X-Backend-Name $upstream_http_name;
}

3️⃣ Conditional logic

if ($upstream_http_name = "internal-service") {
    return 403;
}

🔹 Important Notes

• It only works after a successful upstream response

• If the upstream doesn’t return the header → variable is empty

• Works with:

  • proxy_pass
  • fastcgi_pass
  • uwsgi_pass
  • grpc_pass

🔹 Related Variables