# Issue with proxy\_cache\_key after rewrite **URL:** \ **Category:** NGINX\ **Created:** [December 24, 2010, 11:58pm UTC](https://www.ruby-forum.com/t/issue-with-proxy-cache-key-after-rewrite/200919 "2010-12-24T23:58:29Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![nikuSESS](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/n/f17d59/32.png) [@nikuSESS](https://www.ruby-forum.com/u/nikuSESS)\ **Post date:** [December 24, 2010, 11:58pm UTC](https://www.ruby-forum.com/t/issue-with-proxy-cache-key-after-rewrite/200919/1 "2010-12-24T23:58:29Z")
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 $request\_uri is not rewritten when defined as key, but it seems to be rewritten by default. Seems like a bug to me…? Regards, Sven ---
**Author:** ![Sven\_SDarkmanS\_Mich](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/e99b99/32.png) [@Sven\_SDarkmanS\_Mich](https://www.ruby-forum.com/u/Sven_SDarkmanS_Mich)\ **Post date:** [December 25, 2010, 2:31am UTC](https://www.ruby-forum.com/t/issue-with-proxy-cache-key-after-rewrite/200919/2 "2010-12-25T02:31:04Z")
Hi, > So i’ve added the following: > proxy\_cache\_key “$scheme$host$request\_uri”; Try using “$scheme$host$uri$is\_args$args” 😉 > 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](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. \< [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) \> ---
**Author:** ![Sven\_SDarkmanS\_Mich](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/e99b99/32.png) [@Sven\_SDarkmanS\_Mich](https://www.ruby-forum.com/u/Sven_SDarkmanS_Mich)\ **Post date:** [December 25, 2010, 2:42am UTC](https://www.ruby-forum.com/t/issue-with-proxy-cache-key-after-rewrite/200919/3 "2010-12-25T02:42:20Z")
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” 😉 > 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](http://mysite.com) and [smysite.com](http://smysite.com) https + [mysite.com](http://mysite.com) = http + [smysite.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. ---
**Author:** ![Sven\_SDarkmanS\_Mich](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/e99b99/32.png) [@Sven\_SDarkmanS\_Mich](https://www.ruby-forum.com/u/Sven_SDarkmanS_Mich)\ **Post date:** [December 25, 2010, 2:44pm UTC](https://www.ruby-forum.com/t/issue-with-proxy-cache-key-after-rewrite/200919/4 "2010-12-25T14:44:14Z")
Hi, Am 25.12.2010 04:48, schrieb Maxim D.: > [1] [Модуль ngx\_http\_proxy\_module](http://sysoev.ru/nginx/docs/http/ngx_http_proxy_module.html#proxy_cache_key) > Aww, okay. So its a wiki documentation Bug. 🙂 Thanks a lot, works now. Regards, Sven ---
**Author:** ![Sven\_SDarkmanS\_Mich](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/e99b99/32.png) [@Sven\_SDarkmanS\_Mich](https://www.ruby-forum.com/u/Sven_SDarkmanS_Mich)\ **Post date:** [December 25, 2010, 4:49am UTC](https://www.ruby-forum.com/t/issue-with-proxy-cache-key-after-rewrite/200919/5 "2010-12-25T04:49:28Z")
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] > **[Модуль ngx\_http\_proxy\_module](http://nginx.org/ru/docs/http/ngx_http_proxy_module.html)** Maxim D.