Hi All I'm having no luck doing something which I expected to be very simple, = yet has me completely stumped. I'll give you an overview of what I am = trying to do and then my problems. Any help is appreciated. In short, I want to put squid in front of apache which is serving images = dynamically (ie generating them from a script) and cache them for the = period specified by the script as it will vary per image. I am going to = have different lifespans for the images and I am testing with a max-age = of 10 minutes but in production it could be as little as 2 seconds. At = this point I'm hoping you're thinking "A basic http accelerator, ok". So one of my questions might not really squid specific but if anyone = know you will. Squid is not caching the images and I suspect it's due to = the headers being generated. I get TCP_REFRESH_MISS/200 every time, even = with a 10 minute age. The browser is sending a "If-Modified-Since" = header as well as a "Cache-Controlmax-age=3D0" and I suspect this is = part of the problem. I have set an Expires, Etag, "Cache-Control: = max-age=3D600, s-max-age=3D600, must-revalidate", "Content-Length and = Last-Modified headers in the response to no avail. Can you advise on = how to set the headers properly to get squid to cache them? Here is an = example request/response. My test script is pretty dumb so I can't keep = track of a last-modified date across sessions, but if I do not send a = last modified header in the response the browser does not use an = if-modified-since header in the subsequent request, but there is still = no caching. Request headers: Host: 192.168.13.31 User-Agent: Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.6; en-US; = rv:1.9.2.13) Gecko/20101203 Firefox/3.6.13 Accept: text/html,application/xhtml+xml,application/xml;q=3D0.9,*/*;q=3D0.= 8 Accept-Language: en-us,en;q=3D0.5 Accept-Encoding: gzip,deflate Accept-Charset: ISO-8859-1,utf-8;q=3D0.7,*;q=3D0.7 Keep-Alive: 115 Connection: keep-alive If-Modified-Since: Fri, 18 Feb 2011 15:42:29 GMT If-None-Match: 6382.jpg Cache-Control: max-age=3D0 Response headers: Date: Fri, 18 Feb 2011 15:42:33 GMT Server: Apache/2.2.14 (Win32) SVN/1.6.15 mod_python/3.3.2-dev-20080819 = Python/2.6.4 DAV/2 mod_perl/2.0.4-dev Perl/v5.10.1 Expires: Fri, 18 Feb 2011 15:52:35 GMT Etag: 6382.jpg Cache-Control: max-age=3D600, s-max-age=3D600, must-revalidate Content-Length: 15965 Last-Modified: Fri, 18 Feb 2011 15:42:35 GMT Content-Type: image/jpg X-Cache: MISS from PowerSpecG158 X-Cache-Lookup: HIT from PowerSpecG158:80 Via: 1.1 PowerSpecG158:80 (squid/2.7.STABLE8) Connection: keep-alive If you think this approach is bad and you have a better way, I am all = ears. I have tried a mod_rewrite rule to check for the existence of a = static file and serve it if it exists, otherwise call the script which = generates both the static file and returns the content, but the files = would need to be purged when they are stale and at rapid refresh rates I = found I could easily get timing issues with the check for the static = file succeeding, but then apache not being able to find the find when it = goes to serve it. Lastly, I was unable to setup squid on an alternate port - say 8081, and = use an existing apache on port 80, both on the same box. This is for = testing so I can run squid in parallel with the existing service without = changing the port it is on. Squid seems to want to use the same port = for the origin server as itself and I can't figure out how to say = "listen in 8081 but send requests to port 80 of the origin server". Any = thoughts on this? I am using another server right now to get around = this, but it would be more convenient to use the same box. tia, charles
