How to add a response header on nginx when using p

Question

I want to add a custom header for the response received from the server behind nginx.

While add_header works for nginx-processed responses, it does nothing when the proxy_pass is used.

Answer 1

add_header works as well with proxy_pass as without. I just today set up a configuration where I've used exactly that directive. I have to admit though that I've struggled as well setting this up without exactly recalling the reason, though.

Right now I have a working configuration and it contains the following (among others):

server {
    server_name  .myserver.com
    location / {
        proxy_pass  http://mybackend;
        add_header  X-Upstream  $upstream_addr;
    }
}

Before nginx 1.7.5 add_header worked only on successful responses, in contrast to the HttpHeadersMoreModule mentioned by Sebastian Goodman in his answer.

Since nginx 1.7.5 you can use the keyword always to include custom headers even in error responses. For example:

add_header X-Upstream $upstream_addr always;

---

Limitation: You cannot override the server header value using add_header.

Answer 2

As oliver writes:

add_header works as well with proxy_pass as without.

However, as Shane writes, as of Nginx 1.7.5, you must pass always in order to get add_header to work for error responses, like so:

add_header  X-Upstream  $upstream_addr always;

Answer 3

There is a module called HttpHeadersMoreModule that gives you more control over headers. It does not come with Nginx and requires additional installation. With it, you can do something like this:

location ... {
  more_set_headers "Server: my_server";
}

That will "set the Server output header to the custom value for any status code and any content type". It will replace headers that are already set or add them if unset.

Answer 4

You could try this solution :

In your location block when you use proxy_pass do something like this:

location ... {

  add_header yourHeaderName yourValue;
  proxy_pass xxxx://xxx_my_proxy_addr_xxx;

  # Now use this solution:
  proxy_ignore_headers yourHeaderName // but set by proxy

  # Or if above didn't work maybe this:
  proxy_hide_header yourHeaderName // but set by proxy

}

I'm not sure would it be exactly what you need but try some manipulation of this method and maybe result will fit your problem.

Also you can use this combination:

proxy_hide_header headerSetByProxy;
set $sent_http_header_set_by_proxy yourValue;