sf.586586.redirect-via-proxy-rewrite-and-preserve-url.nginx.conf

# Author: Constantine A. Murenin (cnst)		http://cnst.su/
#
# https://serverfault.com/a/870644/110020
# https://serverfault.com/questions/586586/nginx-redirect-via-proxy-rewrite-and-preserve-url/870644#870644
#
# curl 127.0.0.1:6586 | tcsh | & sed 's#^#\t#g'
#
server {
	listen 6586;
	# https://serverfault.com/questions/379675/nginx-reverse-proxy-url-rewrite/870620#870620
	location /some/path/ {
		proxy_pass http://localhost:6587/; # note the trailing slash!
	}
	# now handle the case where absolute paths are used by the backend:
	# reconstruct the full implied path from the HTTP Referer header
	location / {
		error_page 404 = @404;
		return 404; # this would normally be `try_files` first
	}
	location @404 {
		add_header Vary Referer; # sadly, no effect on 404
		if ($http_referer ~ ://[^/]*(/some/path|/the/other)/) {
			return 302 $1$uri;
		}
		return 404 "Not Found\n";
	}
	# just a fun way to automate running the proof-of-concept tests next
	location = / {
		set $t "/and/more.gif |& fgrep -e HTTP/ -e Referer -e Location";
		return 200
"#!/bin/tcsh
set verbose
curl -v -H 'Referer: http://example.su/some/path/page.html' localhost:6586$t
curl -v localhost:6586$t
curl -v localhost:6586/some/path$t -e uri
";
	}
}
server {
	listen 6587;
	return 200 request_uri:\t$request_uri\n;
}