# Help with X-Accel-Redirect and "rewrite or internal redirection cycle" errors

**URL:** <https://www.ruby-forum.com/t/help-with-x-accel-redirect-and-rewrite-or-internal-redirection-cycle-errors/207922>\
**Category:** NGINX\
**Created:** [June 6, 2011, 2:51pm UTC](https://www.ruby-forum.com/t/help-with-x-accel-redirect-and-rewrite-or-internal-redirection-cycle-errors/207922 "2011-06-06T14:51:43Z")\
**Posts on this page:** 7\
**Page:** 1

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**Author:** ![dubstep](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/cdc98d/32.png) [@dubstep](https://www.ruby-forum.com/u/dubstep)\
**Post date:** [June 6, 2011, 2:51pm UTC](https://www.ruby-forum.com/t/help-with-x-accel-redirect-and-rewrite-or-internal-redirection-cycle-errors/207922/1 "2011-06-06T14:51:43Z")

</div>

Hi,

I’m trying to use X-Accel-Redirect from a Ruby app to hand over  
downloading of a file to Nginx, but it fails and the error in the logs  
is:

2011/06/03 09:18:16 [error] 20500#0: \*37 rewrite or internal redirection  
cycle while internal redirect to “/files/file.m4a” while reading  
response header from upstream, client: 10.0.1.23, server: hercules,  
request: “GET  
/download/e2a25db11bdbdd783531783eaa16eafdfc86355b/1307089096/file.m4a/  
HTTP/1.1”, upstream:  
“[http://127.0.0.1:8679/download/e2a25db11bdbdd783531783eaa16eafdfc86355b/1307089096/file.m4a/](http://127.0.0.1:8679/download/e2a25db11bdbdd783531783eaa16eafdfc86355b/1307089096/file.m4a/)”,  
host: “fakehost.blob”, referrer: “[http://fakehost.blob/music/file.m4a](http://fakehost.blob/music/file.m4a)”

Here is the Nginx config from sites-available:

upstream fakehost.blob {  
server 127.0.0.1:8679;  
server 127.0.0.1:8680;  
}

server {  
listen 80;

server\_name fakehost.blob;

access\_log /var/log/nginx/fakehost.blob.log main;  
error\_log /var/log/nginx/fakehost.blob.error.log info;

location /files {  
internal;  
alias /Users/www/sites/$http\_host/assets/files;  
}

location / {  
proxy\_pass http://$http\_host;  
}

location = /50x.html {  
root html;  
}  
}

and in the main nginx.conf:

http {  
server\_names\_hash\_bucket\_size 64;  
include mime.types;  
default\_type application/octet-stream;

log\_format main '$remote\_addr - $remote\_user [$time\_local]  
$request ’  
'“$status” $body\_bytes\_sent “$http\_referer” ’  
‘“$http\_user\_agent” “$http\_x\_forwarded\_for”’;

sendfile on;

keepalive\_timeout 65;## General Options  
ignore\_invalid\_headers on;  
server\_name\_in\_redirect off;  
server\_tokens off;

#TCP  
tcp\_nopush on;  
tcp\_nodelay off;

## Proxy options

proxy\_buffering on;  
#proxy\_cache\_min\_uses 3;  
proxy\_set\_header X-Real-IP $remote\_addr;  
proxy\_set\_header X-Forwarded-For $proxy\_add\_x\_forwarded\_for;  
proxy\_set\_header Host $http\_host;  
proxy\_redirect off;

proxy\_connect\_timeout 90;  
proxy\_send\_timeout 90;  
proxy\_read\_timeout 90;

proxy\_buffer\_size 4k;  
proxy\_buffers 4 32k;  
proxy\_busy\_buffers\_size 64k;  
proxy\_temp\_file\_write\_size 64k;

If anyone is able to give me some insight or help with this I’d be very  
grateful, as I’ve reached the limit (I’m far beyond it!🙂 of my  
knowledge with Nginx.

Regards,  
Iain

---

<div class="post-metadata">

**Author:** ![tensaiji](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/t/6de8d8/32.png) [@tensaiji](https://www.ruby-forum.com/u/tensaiji)\
**Post date:** [June 6, 2011, 3:48pm UTC](https://www.ruby-forum.com/t/help-with-x-accel-redirect-and-rewrite-or-internal-redirection-cycle-errors/207922/2 "2011-06-06T15:48:39Z")

</div>

Thanks for replying.

On 6 Jun 2011, at 14:14, Antnio P. P. Almeida wrote:

> Problably your app is issuing redirects for that request.

I thought that with the /files location that the Ruby app wouldn’t be  
touched once it handed off the download?

> You should  
> issue the X-Accel-Redirect header with the the download location.
> 
> X-Accel-Redirect path/to/download/file
> 
> Only then will the Ruby handling of the file will be overriden and the  
> download handled by Nginx. Cf. [GitHub - nginxinc/nginx-wiki: ARCHIVED -- Source for the now archived NGINX Wiki section of https://www.nginx.com · GitHub](http://wiki.nginx.org/NginxXSendfile)
> 
> — appa

The Ruby code issues the path so it looks like a uri:

```
  headers( {'X-Accel-Redirect' => "/files/#{title}",
            'Content-Type' => "audio/#{File.extname(title)[1..-1]}",
            'Content-Disposition' => "attachment",
            'Content-Transfer-Encoding' => 

```

‘application/octet-stream’,  
‘Content-Length’ =\> File.size( path\_to\_file ).to\_s,  
‘Cache-Control’ =\> ‘no-cache’,  
‘Content-Description’ =\> ‘File Transfer’, })

Here’s an example of an actual header it sends:

D, [Mon 06-06-2011 1439 #82286] DEBUG – : to\_send\_to\_nginx:  
{“X-Accel-Redirect”=\>“/files/file.m4a”, “Content-Type”=\>“audio/m4a”,  
“Content-Disposition”=\>“attachment”,  
“Content-Transfer-Encoding”=\>“application/octet-stream”,  
“Content-Length”=\>“9032392”, “Cache-Control”=\>“no-cache”,  
“Content-Description”=\>“File Transfer”}

so with this:

location /files {  
internal;  
alias /Users/www/sites/$http\_host/assets/files;  
}

it should end up with  
Users/www/sites/fakehost.blob/assets/files/file.m4a ?

It seems to be correct for what I’ve read in the docs and examples -  
does it look right to you?

Regards,  
Iain

---

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**Author:** ![tensaiji](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/t/6de8d8/32.png) [@tensaiji](https://www.ruby-forum.com/u/tensaiji)\
**Post date:** [June 6, 2011, 4:07pm UTC](https://www.ruby-forum.com/t/help-with-x-accel-redirect-and-rewrite-or-internal-redirection-cycle-errors/207922/3 "2011-06-06T16:07:50Z")

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Hello!

On Mon, Jun 06, 2011 at 01:50:42PM +0100, Iain B. wrote:

> I’m trying to use X-Accel-Redirect from a Ruby app to hand over  
> downloading of a file to Nginx, but it fails and the error in  
> the logs is:
> 
> 2011/06/03 09:18:16 [error] 20500#0: \*37 rewrite or internal redirection cycle  
> while internal redirect to “/files/file.m4a” while reading response header from  
> upstream, client: 10.0.1.23, server: hercules, request: “GET  
> /download/e2a25db11bdbdd783531783eaa16eafdfc86355b/1307089096/file.m4a/ HTTP/1.1”,  
> upstream:  
> “[http://127.0.0.1:8679/download/e2a25db11bdbdd783531783eaa16eafdfc86355b/1307089096/file.m4a/](http://127.0.0.1:8679/download/e2a25db11bdbdd783531783eaa16eafdfc86355b/1307089096/file.m4a/)”,  
> host: “fakehost.blob”, referrer: “[http://fakehost.blob/music/file.m4a](http://fakehost.blob/music/file.m4a)”

Please note “server: hercules”.

[…]

> server {  
> listen 80;
> 
> server\_name fakehost.blob;

This is not the server where request is processed.

Maxim D.

---

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**Author:** ![tensaiji](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/t/6de8d8/32.png) [@tensaiji](https://www.ruby-forum.com/u/tensaiji)\
**Post date:** [June 6, 2011, 3:18pm UTC](https://www.ruby-forum.com/t/help-with-x-accel-redirect-and-rewrite-or-internal-redirection-cycle-errors/207922/4 "2011-06-06T15:18:20Z")

</div>

On 6 Jun 2011 13h50 WEST, [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote:

> /download/e2a25db11bdbdd783531783eaa16eafdfc86355b/1307089096/file.m4a/  
> server 127.0.0.1:8679;
> 
> location = /50x.html {  
> root html;  
> }  
> }

Problably your app is issuing redirects for that request. You should  
issue the X-Accel-Redirect header with the the download location.

X-Accel-Redirect path/to/download/file

Only then will the Ruby handling of the file will be overriden and the  
download handled by Nginx. Cf. [GitHub - nginxinc/nginx-wiki: ARCHIVED -- Source for the now archived NGINX Wiki section of https://www.nginx.com · GitHub](http://wiki.nginx.org/NginxXSendfile)

— appa

---

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**Author:** ![tensaiji](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/t/6de8d8/32.png) [@tensaiji](https://www.ruby-forum.com/u/tensaiji)\
**Post date:** [June 6, 2011, 4:23pm UTC](https://www.ruby-forum.com/t/help-with-x-accel-redirect-and-rewrite-or-internal-redirection-cycle-errors/207922/5 "2011-06-06T16:23:54Z")

</div>

On 6 Jun 2011, at 15:07, Maxim D. wrote:

> Please note “server: hercules”.
> 
> […]
> 
> > server {  
> > listen 80;
> > 
> > server\_name fakehost.blob;
> 
> This is not the server where request is processed.

Sorry, I made that up 🙂 I didn’t want to use the actual host/server  
name so I filled in some fake bits, and the tasks of Hercules were on my  
mind - probably because getting computers to do what you want can be  
like pushing a rock up a hill endlessly 😃

I should probably have put server: fakehost.blob. Apologies for the  
confusion.

Ah ha! Looking at the original, the server name is from one of the other  
site’s being proxied to. Does this mean I should use an absolute uri for  
the X-Accel-Redirect header?

I’m going to try it now.

Regards,  
Iain

---

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**Author:** ![tensaiji](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/t/6de8d8/32.png) [@tensaiji](https://www.ruby-forum.com/u/tensaiji)\
**Post date:** [June 7, 2011, 3:44am UTC](https://www.ruby-forum.com/t/help-with-x-accel-redirect-and-rewrite-or-internal-redirection-cycle-errors/207922/6 "2011-06-07T03:44:59Z")

</div>

On 6 Jun 2011, at 15:55, Maxim D. wrote:

> If you do care enough about your actual server names but still  
> need help with debugging - reproduce the problem in sandbox with  
> fake names.

Bit harsh, there was no difference to the result from my mistake, and  
trying to back up a position with a false dilemma rarely works. I think  
you’ll find it’s up to me how much information I give about my projects,  
asking for your help doesn’t mean I owe you anything, and giving your  
help doesn’t mean you get to be rude.

> > Ah ha! Looking at the original, the server name is from one of  
> > the other site’s being proxied to. Does this mean I should use  
> > an absolute uri for the X-Accel-Redirect header?
> 
> No. The problem is still the same: redirect loop happens not in  
> the server{} you provided, but in other one.

I’m finding entries for this in the access logs of a different server,  
so I’ll see if whether on redirect the host name is being passed along.

> You haven’t provided any info, so just wild guess: you want to  
> read about proxy\_ignore\_headers directive. See here:
> 
> [GitHub - nginxinc/nginx-wiki: ARCHIVED -- Source for the now archived NGINX Wiki section of https://www.nginx.com · GitHub](http://wiki.nginx.org/HttpProxyModule#proxy_ignore_headers)

Well, to say I haven’t provided any info is quite a stretch, and if  
there was other information you thought I should give I think you would  
be better to say what it is, but thankyou for your help anyway, I’ll  
give it a look.

Regards,  
Iain

---

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**Author:** ![tensaiji](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/t/6de8d8/32.png) [@tensaiji](https://www.ruby-forum.com/u/tensaiji)\
**Post date:** [June 6, 2011, 4:56pm UTC](https://www.ruby-forum.com/t/help-with-x-accel-redirect-and-rewrite-or-internal-redirection-cycle-errors/207922/7 "2011-06-06T16:56:03Z")

</div>

Hello!

On Mon, Jun 06, 2011 at 03:23:09PM +0100, Iain B. wrote:

> > > 
> > 
> > This is not the server where request is processed.
> 
> Sorry, I made that up 🙂 I didn’t want to use the actual  
> host/server name so I filled in some fake bits, and the tasks of  
> Hercules were on my mind - probably because getting computers to  
> do what you want can be like pushing a rock up a hill endlessly  
> 😃
> 
> I should probably have put server: fakehost.blob. Apologies for  
> the confusion.

There are two options:

1. You understand things enough to mangle logs and configs, and  
you don’t need any help with debugging.

2. You need help with debugging.

Choose any one. Obviously with (1) there are no reasons to post  
anything here.

If you do care enough about your actual server names but still  
need help with debugging - reproduce the problem in sandbox with  
fake names.

> Ah ha! Looking at the original, the server name is from one of  
> the other site’s being proxied to. Does this mean I should use  
> an absolute uri for the X-Accel-Redirect header?

No. The problem is still the same: redirect loop happens not in  
the server{} you provided, but in other one.

You haven’t provided any info, so just wild guess: you want to  
read about proxy\_ignore\_headers directive. See here:

> **[GitHub - nginxinc/nginx-wiki: ARCHIVED -- Source for the now archived NGINX Wiki...](https://github.com/nginxinc/nginx-wiki)**
>
> ARCHIVED -- Source for the now archived NGINX Wiki section of https://www.nginx.com

Maxim D.