X-Accel-Redirect problem with proxy_pass and proxy_set_heder

[gansbrest]

Will try to describe the problem we have:

We are doing proxy_pass to another domain and change host header (as you can see below), backend returns X-Accel-Redirect with the location of the file to serve, but for some reason on step 3 belowб when nginx receives X-Accel-Redirectб it's using original Host, not the one we changed with proxy_set_header.. which means it's captured by wrong server section and 404 as a result..

---

curl -I ​http://beta.fastcodesign.com/blablabla/asset_files/-/2014/01/31/telecasts.csv

1) Internally we override Host header to beta.assets.fastcodesign.com and proxy_pass

location ~* ^{/blablabla/(.*) {}

proxy_set_header HOST beta.assets.fastcompany.com;
proxy_pass ​http://txjp/$1$is_args$args;

}

upstream txjp {

server localhost:8880;

}

2) Using tcpdump on port 8880 we can see that request goes to backend with new header beta.assets.fastcompany.com

V)..V)..HEAD /asset_files/-/2014/01/31/telecasts.csv HTTP/1.0^{M
HOST: beta.assets.fastcompany.com}M
Connection: close^{M
User-Agent: curl/7.24.0 (x86_64-redhat-linux-gnu) libcurl/7.24.0 NSS/3.12.10.0 zlib/1.2.5 libidn/1.18 libssh2/1.2.2}M
Accept: */*^M

HTTP/1.1 200 OK^{M
x-rid: 1ok5rjv}M
Etag: "165143ec0b37d43cf2c2b7f292647526"^{M
Date: Sat, 01 Feb 2014 00:07:47 GMT}M
Last-Modified: Fri, 31 Jan 2014 18:15:36 GMT^{M
Content-Type: application/json; charset=utf-8}M
Content-Length: 1212^{M
Cache-Control: max-age=1801}M
X-Accel-Redirect: /internal_redirect/assets.fastcompany.com.s3-website-us-east-1.amazonaws.com/asset_files/-/2014/01/31/telecasts.csv^{M
X-Response-Time: 69ms}M
Connection: close^M

3) X-Accel-Redirect should tell nginx to go fetch that url, but it seems like it uses original host (beta.fastcodesign.com) instead the one we modified with proxy_pass

HEAD /internal_redirect/assets.fastcompany.com.s3-website-us-east-1.amazonaws.com/asset_files/-/2014/01/31/telecasts.csv HTTP/1.0^{M
X-Real-IP: 23.23.118.249}M
X-Forwarded-For: 23.23.118.249^{M
Host: beta.fastcodesign.com}M
X-Geo: US^{M
Connection: close}M
User-Agent: curl/7.24.0 (x86_64-redhat-linux-gnu) libcurl/7.24.0 NSS/3.12.10.0 zlib/1.2.5 libidn/1.18 libssh2/1.2.2^{M
Accept: */*}M

TTP/1.1 404 Not Found^{M
x-rid: hwii1c}M
Content-Type: application/json; charset=utf-8^{M
Content-Length: 2}M
X-Response-Time: 288ms^{M
Date: Sat, 01 Feb 2014 00:07:47 GMT}M
Connection: close

[gansbrest]

We also tried to set full path on the backend for the X-Accel-Redirect header including Host ( ie X-Accel-Redirect ​http://domain.com/file ) but it returns same error, probably hostname in x-accel-redirect is not supported..

[Maxim Dounin]

The X-Accel-Redirect header is to do an internal redirect to the specified URI, see ​proxy_ignore_headers and ​internal. If you want nginx to proxy a redirected request to another domain, you have to write a location block to do this.