Help debugging cacheability / ttl information?
Hi,
We have a setup with varnish in front of a lighttpd+fastcgi combo. For some
reason or other the application doesn't send any cache control headers. Instead
of doing the sensible thing (prodding the developers to fix it in the backend)
I have taken it upon myself to fix it via VCL.
However my feeble attempts at being smart have so far failed elegantly, and I
am left scratching my head a bit.
What I really am looking for is some help with how to best debug the setup with
regards to TTLs and cacheability. I'd like to be able to inspect a specific
cached objects TTL to see if my set obj.ttl overrides actually work or not.
What is the best way to do that?
On the client I use firebug, so all headers and responess are readily available
on that end. The reason I don't think everything is as it should is that the
Age header is very low most of the time.
For the record we are still at varnish 1.0.4 and here is the current VCL (I've
taken out the stuff that was obviously not working anyway) :
backend default {
set backend.host = 127.0.0.1;
set backend.port = 80;
}
sub vcl_recv {
if (req.request == GET req.http.cookie) {
lookup;
}
if (req.request == GET req.url ~ \.(gif|jpg|swf|css|js)$) {
lookup;
}
}
sub vcl_fetch {
if (obj.ttl 120s) {
set obj.ttl = 120s;
}
if (resp.http.Set-Cookie) {
insert;
}
}
Any help will be highly appreciated!
Regards
--
Denis
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Re: Varnish and awstats
From: jdouglas [EMAIL PROTECTED] Is there a trick to getting awstats to work with varnish? I tried doing varnishncsa -a -w filename and then pointed awstats to this file but it gives me an error that the log format must be incorrect a bad format or LogFormat parameter setup does not match this format. Your AWStats LogFormat parameter is: 4 This means each line in your web server log file need to have common log format like this Try setting the Combined logformat instead, which is what varnishncsa produces.. From the varnishncsa man page : Display Varnish logs in Apache / NCSA combined log format Regards -- Denis Braekhus - Teknisk Ansvarlig ABC Startsiden AS http://www.startsiden.no ___ varnish-misc mailing list varnish-misc@projects.linpro.no http://projects.linpro.no/mailman/listinfo/varnish-misc
Re: Varnish - configuration
From: Kamil Radziszewski [EMAIL PROTECTED]
How to configure varnish to cache files from website that is on anoter IP
adress as the varnish ?
man vcl gives you info on the backend directive to use in your vcl config:
backend default {
set backend.host = www.example.com;
set backend.port = 80;
}
You can also use more than one backend, but instead of quoting the entire
manpage, [EMAIL PROTECTED] better if you check it yourself really.
Regards
--
Denis Braekhus - Teknisk Ansvarlig ABC Startsiden AS
http://www.startsiden.no
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Re: Failure cenarios?
- Gaute Amundsen [EMAIL PROTECTED] wrote: I have come to understand that in some builds under some conditions varnish may hang or a crash. (we run 1.0.4-3el4.i386.rpm) Hi Gaute, I'll just say that in my experience Varnish has proven itself to be extremely stable. We actually run 1.0.3 across the board (yes I know there are known bugs, however we do not experience them at all) and Varnish currently serves up all requests at www.startsiden.no and www.abcnyheter.no. If anything breaks, it has not so far been varnish. However our scenario is pretty different from yours, we have very few vhosts but each has a very high amount of traffic. There is little or no advanced VCL configuration at all on our sites. We're pretty close to the default. The two sites have a different setup with regards to placement of Varnish. One site runs with dedicated varnish servers, the other has varnish and apache2 on the same box. Now the question is, how do I best detect if varnsih should have a problem? Would it be reasonably reliable to just chek if the pid from /var/run/varnish.pid is running, do I need to fetch a page, or is there some better way? Well, we always monitor as high up as possible to make sure everything works on all levels. Lower level monitoring is useful too, but for pinpointing with more accuracy where the problem is. Regards -- Denis Braekhus - Teknisk Ansvarlig ABC Startsiden AS http://www.startsiden.no ___ varnish-misc mailing list varnish-misc@projects.linpro.no http://projects.linpro.no/mailman/listinfo/varnish-misc
Re: Varnish Dirty Caching
- Dag-Erling Smørgrav [EMAIL PROTECTED] wrote: Christoph [EMAIL PROTECTED] writes: So what is dirty caching and why use it? Think of a very unreliable backend. If varnish can't reach it's backend, it will simply return the last content it has (even if the content is stale). That way i can cover hickups. It's on our list for 2.0, and will probably hit trunk in late July. Way cool, really looking forward to that feature! As I stated in a different thread it's more often other parts of the system that break than varnish so having such a failsafe enables us to do a lot more fault tolerant setups. Regards -- Denis Braekhus - Teknisk Ansvarlig ABC Startsiden AS http://www.startsiden.no ___ varnish-misc mailing list varnish-misc@projects.linpro.no http://projects.linpro.no/mailman/listinfo/varnish-misc
Re: Problem with varnish and caching
- Anup Shukla [EMAIL PROTECTED] wrote: Manuel Amador (Rudd-O) wrote: site is cached according to Varnish default policies. You have not provided a single counterexample or a single snippet of VCL that could solve the problems I have, or a single snippet of VCL that you guys are actually using on production servers. man vcl does provide an example about how to cache even if Cookies are present. Did i miss something? Yeah, I think you missed the fact that Manuel isn't really interested in anything else than spewing out insults and bulls*** on the list. Nothing to see / hear here people move on, just an angry troll. Regards -- Denis Braekhus - Teknisk Ansvarlig ABC Startsiden AS http://www.startsiden.no ___ varnish-misc mailing list varnish-misc@projects.linpro.no http://projects.linpro.no/mailman/listinfo/varnish-misc
Re: Varnish and Perlbal
- André Cruz [EMAIL PROTECTED] wrote: Ok, I'll try it both ways to test. And regarding my other question... Should Perlbal handle the request first, and pass it to some varnish process or should varnish process the request first and send only the misses to PerlBal+Apache? Perlbal is probably better at load-balancing since it is it's core function, no? Thanks for your help, André André, If we can assume one of the reasons you want to use Perlbal is to achieve some sort of failover capability, I would say place Perlbal in front of Varnish. If you have another provision to handle that and you only want to improve performance I would say it depends on your application really. I completely agree with DES though that implementing Varnish locally on the same box as apache is indeed the path of least configuration and fewest changes :P From what I have read on Perlbal it should be suited for placement in front of a cache such as varnish. Could I ask what your experience with Perlbal is? Is it a nice loadbalancer? How does your setup with it look like? What kind of traffice do you see? I gather the Varnish project is looking to implement some sort of basic load balancing capabilities into Varnish at some point in time. Regards -- Denis Braekhus - Teknisk Ansvarlig ABC Startsiden AS http://www.startsiden.no ___ varnish-misc mailing list varnish-misc@projects.linpro.no http://projects.linpro.no/mailman/listinfo/varnish-misc
Re: varnish and Nginx
- Dingo [EMAIL PROTECTED] wrote: How would one compare say varnich with nginx http://wiki.codemongers.com/Nginx where i see Nginx is not only a web server but a balancer for http/pop/imap/smtp Interesting question. I have myself been looking at Nginx, mainly for its capabilities as a web loadbalancer / front-end. From what I've read Nginx is not a cahce per se. It does serve static content (like any other webserver), can be coupled with fastcgi backends to serve dynamic content, and can also be used as an accelerating reverse proxy, in that it handles requests on behalf of slower backend servers (including loadbalancing). It does not (AFAIK) function as a web cache. Varnish is a web cache, and to serve any content at all you need some sort of webserver behind it. Regards -- Denis Braekhus - Teknisk Ansvarlig ABC Startsiden AS http://www.startsiden.no ___ varnish-misc mailing list varnish-misc@projects.linpro.no http://projects.linpro.no/mailman/listinfo/varnish-misc
Re: varnish and Nginx
- Dingo [EMAIL PROTECTED] wrote: So its feasible to run Nginx as the server/load balancer and varnish as the front end cache giving potentially a decent high speed/high capacity design. Well, I have no experience with Nginx whatsoever, but yes, both could be components in a high speed/high capacity design. Regards -- Denis Braekhus - Teknisk Ansvarlig ABC Startsiden AS http://www.startsiden.no ___ varnish-misc mailing list varnish-misc@projects.linpro.no http://projects.linpro.no/mailman/listinfo/varnish-misc
Re: Passing through client IP address to server
- ADOFMS Admin, SteveOC [EMAIL PROTECTED] wrote: There is also a HTTP_X_VARNISH variable set as well, which is just a number. Any idea what this one does ? This number is a request number you can use for debugging. varnishlog outputs these identifiers and you can cross check with the number from the header. Regards -- Denis Braekhus - Teknisk Ansvarlig ABC Startsiden AS http://www.startsiden.no ___ varnish-misc mailing list varnish-misc@projects.linpro.no http://projects.linpro.no/mailman/listinfo/varnish-misc
Re: Current Varnish status?
- Kenneth Rørvik [EMAIL PROTECTED] wrote: Denis Brækhus wrote: So, my question is, how stable do you consider the current release to be? (http://www.hio.no) for three weeks + now. In that time, there's been one major incident, in which varnish suddenly started dropping all incoming connections, possibly resetting, with clients ending up simply with blank pages. Thanks for the info. I added a content script check to my alteons, checking for the length of a particular object through http. This should eliminate any major mishaps I guess. So my setup ended up being : VarnishServer1VarnishServer2 | | AppServer1AppServer2 If VarnishServer1 or 2 fails the alteon falls back to using the relevant appserver directly instead.. Looking forward to see how this performs under load. I have high expectations for Varnish actually :) Regards -- Denis Braekhus - Teknisk Ansvarlig ABC Startsiden AS http://www.startsiden.no ___ varnish-misc mailing list varnish-misc@projects.linpro.no http://projects.linpro.no/mailman/listinfo/varnish-misc
