X-Accel-Redirect testing

Hello,
I’d like to test if I set up my configs properly and if they’re working.
Should it work if I send a GET request with the X-Accel-Redirect header?
I am using Mozilla plugin “Modify Headers”. I have added:
“X-Accel-Redirect
/index” and my request on the server is:
(captured with tcpdump)

User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:11.0) Gecko/20100101
Firefox/11.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,/;q=0.8
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip, deflate
Connection: keep-alive
X-Accel-Redirect: /index

My vhost config in nginx is:

server {
listen 80;
server_name aa.com; #it’s added in my hosts file
location / {
alias /var/www;
internal;
}
}

Path is:

ls -lh /var/www/
index

Error is 404 Not Found - nothing logged in error.log though …

My environment would actually be Apache as frontend which passes
requests
with X-Accel-Redirect to Nginx which serves static files.
But right now I’m in testing phase.

Posted at Nginx Forum:

On 25 September 2012 23:28, w00t [email protected] wrote:

Hello,
I’d like to test if I set up my configs properly and if they’re working.
Should it work if I send a GET request with the X-Accel-Redirect header?

No. This is a /response/ header from (typically) a dynamic backend
which instructs nginx to serve some piece of static content, thus
freeing up the backend for more intelligent, heavy-weight request
handling. There are more sophisticated uses, but you should at least
understand this basic use case before attempting them.

Regards,
Jonathan

Jonathan M. // Oxford, London, UK
http://www.jpluscplusm.com/contact.html

Jonathan M. Wrote:

No. This is a /response/ header from (typically) a dynamic backend
which instructs nginx to serve some piece of static content, thus
freeing up the backend for more intelligent, heavy-weight request
handling. There are more sophisticated uses, but you should at least
understand this basic use case before attempting them.

Hello Jonathan,

Thanks for the reply. I’d love to at least understand the basics, in
fact
this is what I’m trying to do. It’s a bit hard when there’s no thorough
documentation and all responses found on internet are vague.

You are saying that it will work only when Nginx is a reverse proxy and
receives a response from another backend, like Apache. But I want Apache
as
frontend and Nginx as backend. Should I focus on Xsendfile?

Posted at Nginx Forum:

On 26 Set 2012 10h17 CEST, [email protected] wrote:

Thanks for the reply. I’d love to at least understand the basics, in
fact this is what I’m trying to do. It’s a bit hard when there’s no
thorough documentation and all responses found on internet are
vague.

You are saying that it will work only when Nginx is a reverse proxy
and receives a response from another backend, like Apache. But I
want Apache as frontend and Nginx as backend. Should I focus on
Xsendfile?

XSendfile in Nginx is called X-Accel-Redirect.

The way X-Accel-Redirect works is that your app/backend sends a
“special” header with the location of the file that is to be served by
Nginx. Usually the application case is for speeding up the delivery of
protected/private files. Let’s say you have a ecommerce site that
sells digital downloads. Then these files will be protected and for
speeding up the delivery your application sends an X-Accel-Redirect
header with the location of the file. Then the file is delivered by
Nginx as a regular static file.

Example: I request to download:

The file is stocked at /path/to/the/flac_files/big_hit.flac

your ecommerce sends an header:

X-Accel-Redirect: /path/to/the/flac_files/big_hit.flac

when Nginx sees this he knows that now the file is to be served
directly from the file system as a regular static file. Note that the
real location is hidden from the client.

Note that the real location must be protected from direct access by
the client always, be it from your app, be it from your server, for
example using the internal keyword:

http://nginx.org/en/docs/http/ngx_http_core_module.html#internal

In a nutshell that’s how it works.

HTH,
— appa

António P. P. Almeida Wrote:

when Nginx sees this he knows that now the file is to be served
directly from the file system as a regular static file. Note that the
real location is hidden from the client.

Note that the real location must be protected from direct access by
the client always, be it from your app, be it from your server, for
example using the internal keyword:

Module ngx_http_core_module

In a nutshell that’s how it works.

I ended up using nginx as a reverse proxy, although this is what I
wanted to
avoid in the first place (bandwidth reasons).
Main traffic passes through nginx which forwards it to apache by
proxy_pass,
and apache sends back the X-Accel-Redirect and nginx responds with the
file
(protected with internal; ).

Posted at Nginx Forum:

On 2 Out 2012 14h01 CEST, [email protected] wrote:

protected and for speeding up the delivery your application sends

Module ngx_http_core_module

In a nutshell that’s how it works.

I ended up using nginx as a reverse proxy, although this is what I
wanted to avoid in the first place (bandwidth reasons). Main
traffic passes through nginx which forwards it to apache by
proxy_pass, and apache sends back the X-Accel-Redirect and nginx
responds with the file (protected with internal; ).

Instead of Apache you can make your app return that header. For
example, on drupal there’s a module that sends that header for
protected file systems.

— appa

On Sep 26, 2012, at 1:03 PM, Antnio P. P. Almeida wrote:

Xsendfile?
Nginx as a regular static file.

In a nutshell that’s how it works.
Some big users are even doing fancy “hybrid cloud” with nginx this way
:slight_smile:

In such scenarios they might have an application on premises and the
content on Amazon S3 (or vice versa). Instead of doing usual HTTP
redirect to AWS and keeping another part of application on Amazon to
retrieve and serve content to the clients, such installations rely on
internal redirection/secure retrieval.

Some of them chose to deploy nginx just because of how this particular
feature works.

HTH,
— appa


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