Issue with proxy_cache_key after rewrite

Server NGINX
1

Hi,

i’ve run a few tests with the nginx proxy module. I would like to have
my content cached with the “$scheme$host$request_uri” key, like
suggested
on the wiki page[1]. So i’ve added the following:
proxy_cache_key “$scheme$host$request_uri”;

into the http {} block. After the test i’ve checked the keys which are
used
in the cached files and noticed that the key was
httpmy_vhost/original_request_uri

but i’ve a perl module which does a internal_redirect which rewrites
some
paths like /olddir/ to /.

Now we have the following request:
http//my_vhost/olddir/documents/test.pdf

so i thought the key should be
httpmy_vhost/documents/test.pdf

but it was
httpmy_vhost/olddir/documents/test.pdf

when i remove the proxy_cache_key from the config i get the following
key:
http://interal_host:internal_port/documents/test.pdf

so something here seems to be “strange”. Because the default key is:
default: $scheme$proxy_host$request_uri;

and now we see the following differences:
first: $scheme seems to be http when beeing used, but http:// when
default.
second: the $request_uri is not rewritten when defined as key, but it
seems
to be rewritten by default.

Seems like a bug to me…?

Regards,
Sven

2

Hi,

So i’ve added the following:
proxy_cache_key “$scheme$host$request_uri”;

Try using “$scheme$host$uri$is_args$args” :wink:

when i remove the proxy_cache_key from the config i get the following key:
http://interal_host:internal_port/documents/test.pdf

so something here seems to be “strange”. Because the default key is:
default: $scheme$proxy_host$request_uri;

No, default key isn’t calculated from variables…
It’s something like: “${proxy_scheme}://$proxy_host$uri$is_args$args”

Also, “$proxy_host” returns whatever you’ve got in your “proxy_pass”
directive, so in case you’ve got “proxy_pass http://127.0.0.1:8000” it
will
return “127.0.0.1:8000”.

first: $scheme seems to be http when beeing used, but http:// when
default.

See above.

second: the $request_uri is not rewritten when defined as key, but it
seems
to be rewritten by default.

“$request_uri” isn’t used in the default cache key.

Best regards,
Piotr S. < [email protected] >

3

Hi,

On 25/12/2010 03:29, Piotr S. wrote:

So i’ve added the following:
proxy_cache_key “$scheme$host$request_uri”;

Try using “$scheme$host$uri$is_args$args” :wink:
Probably putting ‘://’ or something else that won’t be the first
character of a URL (e.g. ‘#’) between $scheme and $host is a good idea,
just in case you have two hosts that only differ by an initial ‘s’ -

e.g. mysite.com and smysite.com

https + mysite.com = http + smysite.com

In most situations this will be fine, but depending on the setup, it
could potentially be a source of bugs or a security hole.

Marcus.

4

Hi,

Am 25.12.2010 04:48, schrieb Maxim D.:

[1] Модуль ngx_http_proxy_module
Aww, okay. So its a wiki documentation Bug. :slight_smile: Thanks a lot, works now.

Regards,
Sven

5

Hello!

On Fri, Dec 24, 2010 at 11:57:30PM +0100, Sven ‘Darkman’ Michels wrote:

httpmy_vhost/olddir/documents/test.pdf
to be rewritten by default.

Seems like a bug to me…?

Default listed in wiki/docs isn’t what actually used by default as
proxy_cache_key. In russian docs[1] you may find something like

By default value is similar to
proxy_cache_key  $scheme$proxy_host$uri$is_args$args;

Word “similar” is key one. Actual value can’t be expressed with
variables. It’s something like $proxy_url - but there are no such
variable.

[1]
http://sysoev.ru/nginx/docs/http/ngx_http_proxy_module.html#proxy_cache_key

Maxim D.