nginx重定向到特定域

Question

I would like to redirect traffic from:

     http://demo.foo.com/a.png
to   http://demo.bar.com/a.png

One caveat is that foo.com and bar.com are both the same box. So I need specify that the redirect occur for foo.com traffic only, to avoid a redirect loop on bar.com traffic.

I tried this:

server {
  server_name  demo.foo.com;
  return       301 $scheme://demo.bar.com$request_uri;
}

After waiting a minute for it to take effect... This looked promising:

curl -I http://demo.foo.com

The 301 appeared as expected. However, there are two issues:

1) running curl -I http://demo.bar.com also came back with a 301 redirect to demo.bar.com (so my server_name filter is not working)
2) after a few more minutes (~2-3) both curl commands stop working, and return a 503 Unavailable message (this may be due to a redirect loop caused by #1)

Answer 1

We are using such constraction:

server {
   ...

   server_name demo.foo.com demo.bar.com;

   if ($http_host = "demo.foo.com") {
      rewrite ^ http://demo.bar.com:$server_port$request_uri permanent;
   }

   ...
}