atom feed8 messages in ru.sysoev.nginxRe: Setting cache parameters via if d...
FromSent OnAttachments
Jeff MitchellJan 27, 2011 9:07 pm 
Ryan MalayterJan 28, 2011 7:55 am 
Jeff MitchellJan 29, 2011 12:19 am 
Jeff MitchellJan 29, 2011 8:05 am 
Guzman BrasoJan 29, 2011 3:57 pm 
agentzhFeb 1, 2011 12:46 am 
agentzhFeb 1, 2011 12:53 am 
Ryan MalayterFeb 1, 2011 7:45 am 
Subject:Re: Setting cache parameters via if directives
From:Ryan Malayter (mala@gmail.com)
Date:Feb 1, 2011 7:45:35 am
List:ru.sysoev.nginx

On Tue, Feb 1, 2011 at 2:47 AM, agentzh <agen@gmail.com> wrote:

On Fri, Jan 28, 2011 at 11:55 PM, Ryan Malayter <mala@gmail.com> wrote:

I do something similar using the conditinal setting of variables inside the if block to set Cache-Control values, perhaps you can use a similar method to set the values of proxy_cache_valid. Since setting variables is one of the few "safe" things to do inside an if block, and most directives can take variables as agurments, it is generally useful.

location / {   set $mycc = "private, max-age=0";

  if ($foo = "bar") {      set $mycc = "public, max-age=3600"      }

 proxy_pass http://backend;  add_header Cache-Control $mycc; }

I'm amazed to see the config above works for you. I'm not sure if you're using some ancient versions of nginx that I know very little about (like 0.6.x or 0.5.x or even earlier).

Consider the following config snippet:

   location /test {        set $a 3;        if ($a = 3) {            set $a 4;        }        echo $a;    }

GET /test will give you nothing for nginx 0.7.21 ~ 0.9.4. Don't tell me that the ngx_echo module's echo directive is buggy because it's too dead simple to get wrong.

Basically for "modern" versions of nginx, the location "if" block creates an anonymous nested location and will trap the execution flow, that is, once you get in, you'll never go out of it to reach the content phase. And that's one of the reasons why people call nginx's "if" an evil monster ;)

It does in fact work in production on nginx 0.7.6x. Below is my actual configuration (trimmed to the essentials and with a few substitutions of actual URIs).

location /MyApp { proxy_pass http://backendTomcat; proxy_set_header Host $host; proxy_read_timeout 900; proxy_next_upstream error timeout; proxy_redirect http://example.com/ $scheme://example.com/;

#hide caching related headers from backend #the backend is dumb about this but we can't change it proxy_hide_header Pragma; proxy_hide_header Cache-Control; proxy_hide_header Expires;

#these variables are the new values for caching headers

set $mycc "private,max-age=0"; set $myexp "Fri, 01 Jan 1990 00:34:56 GMT";

#create a variable that includes both scheme and URI so we #can redirect in and out of SSL if needed set $schemeuri $scheme$uri;

#add exception for dynamic CSS stylesheet, make it cache for 1 hour if ($request_uri ~* uiframework\.Theme) { set $mycc "private,max-age=3600"; set $myexp ""; } if ($schemeuri = "http/MyApp/changePassword") { rewrite ^(.*)$ https://$host$1 redirect; }

#add our new headers add_header "Cache-Control" $mycc; add_header "Expires" $myexp; }

-- RPM

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