(sorry for top-posting)
I believe varnishlog has all you need:
54 BackendOpen b backend_name source_ip source_port dest_ip dest_port
Just track the id on the left (54 in this case) for the request and response
and you should be able to find the culprit.
From: [email protected]
[mailto:[email protected]] On Behalf Of Stefan Pommerening
Sent: Wednesday, 9 February 2011 9:47 PM
To: [email protected]
Subject: How to find out a single failing backend from a round-robin
director?(Inline-C)
Hi all,
I'm working with a set of varnish-caches (2.1.3) in front of some round-robin
director configured backends.
Sometimes I experience a 503 error due to some unforseeable circumstances like
network hiccups, content server problems and other magic... ;-)
Nevertheless all backends are healthy regarding the large majority of other
requests (and watchdog of course), we deal with sporadic failures here.
Obviously I don't want those 503's to go through to the user.
I inserted the following code in my vcl_fetch:
if (beresp.status == 503) {
set beresp.saintmode = 2s;
restart;
}
This works quite well, the failed (503 delivering) request is forwarded to the
next backend in the director and is successfully served then.
What I am missing is the exact backend information which backend did not serve
the request or better said: where did the 503 come from?
I already included some inline-C in order to send info to syslog, but I am
missing some VRT_(r_)something to find out the failing backend without
searching the backend's logfiles directly.
My current syslog()-msg is:
syslog (LOG_LOCAL7 | LOG_INFO, "VarnishLog(vcl_fetch): %s/%s[%s] [REST=%02d] %s
http://%s%s <http://%25s%25s> ",
VRT_backend_string(sp), VRT_r_server_hostname(sp),
VRT_IP_string(sp,VRT_r_server_ip(sp)),
VRT_r_req_restarts(sp), VRT_r_req_request(sp), VRT_GetHdr(sp, HDR_REQ,
"\005host:"), VRT_r_req_url(sp));
I managed to get the backend definition, but not the specific backend machine
name (or IP) from the backend director.
... and: is there some sort of overview on which VRT_magic fields (for use with
inline-C) exists?
Thanks in advance,
Stefan
--
Dipl.-Inform. Stefan Pommerening
Informatik-Büro: IT-Dienste & Projekte, Consulting & Coaching
http://www.dmsp.de
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