Mailing List Archive

#1791: Varnish send request to wrong servers without any logging
---------------------+----------------------
Reporter: webmons | Type: defect
Status: new | Priority: high
Milestone: | Component: varnishd
Version: 3.0.7 | Severity: critical
Keywords: |
---------------------+----------------------
We route requests to different backend based on whether it's mobile and
its url. We start seeing infrequent but steady stream of requests being
routed to a wrong backend. We turned on varnishlog but found no trace of
those requests but our backend log show that they did go through varnish

Anyone has experience this issue

Here is detail info

'''Which varnish version:'''
3.0.7
'''
Which type of CPU ?'''
2 CPU
processor : 0
vendor_id : GenuineIntel
cpu family : 6
model : 62
model name : Intel(R) Xeon(R) CPU E5-2670 v2 @ 2.50GHz
stepping : 4
microcode : 0x415
cpu MHz : 2500.106
cache size : 25600 KB

'''32 or 64 bit mode ?'''
64

'''how much RAM ?'''
14G

'''Which OS/kernel version ?'''
Ubuntu
Kernel 3.13.0-48-generic

'''VCL'''

{{{

import std;
import ipcast;
import header;
include "devicedetect.vcl";

acl block_ips {
}

backend zfront1 {
.host = "10.0.1.70";
.port = "80";
.connect_timeout = 600s;
.first_byte_timeout = 600s;
.between_bytes_timeout = 600s;
}
backend api1 {
.host = "10.0.1.251";
.port = "80";
.connect_timeout = 600s;
.first_byte_timeout = 600s;
.between_bytes_timeout = 600s;
}
backend mobile1 {
.host = "10.0.1.249";
.port = "80";
.connect_timeout = 600s;
.first_byte_timeout = 600s;
.between_bytes_timeout = 600s;
}

backend quoted {
.host = "10.0.1.250";
.port = "80";
.connect_timeout = 600s;
.first_byte_timeout = 600s;
.between_bytes_timeout = 600s;
}
director zfrontCluster round-robin {
{
.backend = zfront1;
}
}
director apiCluster round-robin {
{
.backend = api1;
}
}
director mobileCluster round-robin {
{
.backend = mobile1;
}
}
director quotedCluster round-robin {
{
.backend = quoted;
}
}
sub vcl_recv {
# Pull the IP address from X-Forwarded-For. If we can't parse the IP,
default to 127.0.0.1 so that we let it through
set req.http.xff = regsub(req.http.X-Forwarded-For, "^(^[^,]+),?.*$",
"\1");
if (ipcast.ip(req.http.xff, "127.0.0.1") ~ block_ips) {
error 403 "Forbidden";
}

call devicedetect;
if (req.http.host == "thezebra.com") {
set req.http.host = "www.thezebra.com";
error 750 "https://" + req.http.host + req.url;
}

if (req.url ~ "^/insurance-news/") {
set req.url = regsub(req.url, "^/insurance-news/", "/");
set req.backend = quotedCluster;
} else if (req.url ~ "^/(api|admin|be|al|el|il)/") {
set req.backend = apiCluster;
} else {
if (req.http.host ~ "[A-Z]" || req.url ~ "[A-Z]") {
error 750 "https://" + std.tolower(req.http.host + req.url);
}
if ((req.url ~ "^/(\?.*)?$" || req.url ~ "^/compare/.*") &&
req.http.X-UA-Device ~ "^mobile") {
set req.backend = mobileCluster;
} else {
set req.backend = zfrontCluster;
}
}
}

sub vcl_hash {
if (req.backend == quotedCluster) {
hash_data("/insurance-news/");
}
}

sub vcl_fetch {
# do not cache anything that's not 200.
if (beresp.status != 200) {
set beresp.ttl = 0 s;
}

# mobile-related: Google requires adding vary: user-agent header to
the response to make it mobile-friendly.
# The problem is if varnish see vary: user-agent it'll create
different cache item per user-agent so the following
# code will add vary header with X-UA-Device and vcl_deliver will
replace it with User-agent
# this is assuming backend doesn't add vary: user-agent. If it does,
we'd need to remove it here
if (req.http.X-UA-Device) {
if (!beresp.http.Vary) { # no Vary at all
set beresp.http.Vary = "X-UA-Device";
} elseif (beresp.http.Vary !~ "X-UA-Device") { # add to existing
Vary
set beresp.http.Vary = beresp.http.Vary + ", X-UA-Device";
}
}
}

sub vcl_deliver {
if (obj.hits > 0) {
set resp.http.X-Cache = "HIT";
} else {
set resp.http.X-Cache = "MISS";
}

# to keep any caches in the wild from serving wrong content to client
#2
# behind them, we need to transform the Vary on the way out.
if ((req.http.X-UA-Device) && (resp.http.Vary)) {
set resp.http.Vary = regsub(resp.http.Vary, "X-UA-Device", "User-
Agent");
}

# click stream stuff
# extract subid from the cookie or request url
if (req.http.cookie ~ "subid") {
std.log("subid:" + regsub(req.http.cookie, ".*subid=([^;]*).*",
"\1"));
} elseif (req.url ~ "[&\?]subid=") {
std.log("subid:" + regsub(req.url, ".*[&\?]subid=([^&]*).*",
"\1"));
}

# now extract the channel id. if the channel id isn't specified, then
we want to use the organic channel id
if (req.http.cookie ~ "channel_id") {
std.log("channelid:" + regsub(req.http.cookie,
".*channel\_id=([^;]*).*", "\1"));
} elseif (req.url ~ "[&\?]channelid=") {
std.log("channelid:" + regsub(req.url,
".*[&\?]channelid=([^&]*).*", "\1"));
} else {
std.log("channelid:3acf01");
}

# session id should only be in cookie
if (req.http.cookie ~ "sessionid") {
std.log("sessionid:" + regsub(req.http.cookie,
".*sessionid=([^;]*).*", "\1"));
} else {
std.log("sessionid:" + regsub(header.get(resp.http.set-
cookie,"sessionid="), ".*sessionid=([^;]*).*", "\1"));
}
if (req.http.X-UA-Device ~ "^mobile") {
std.log("mobile:true");
} else {
std.log("mobile:false");
}
}

sub vcl_error {
if (obj.status == 750) {
set obj.http.Location = obj.response;
set obj.status = 301;
return(deliver);
}
}
}}}


'''Behavior:'''
We'd see requests not meant for API cluster routed to it. Most of these
are from bot, like google adsbot or pingdom but quite a few are from
legitimate users
Here is an nginx access log entry from an api server in API cluster

10.0.1.100 0.052 0.052 - [11/Sep/2015:10:56:41 -0500] "GET
/compare/start/bid811/ut?utm_source=google&utm_medium=cpc&utm_campaign
=car-insurance-ut&utm_term=geico-auto-insurance-policy&utm_content=the-
zebra-car-insurance&channelid=ajf201&subid=ut-big-brand-carriers-exact
HTTP/1.1" 404 6655 "-" "AdsBot-Google
(+http://www.google.com/adsbot.html)" "66.249.92.33"

The url path doesn't match this regex ^/(api|admin|be|al|el|il)/, so I'm
completely lost as to why it'd show up there

Neither Varnishlog nor varnishncsa shows anything about this request.

--
Ticket URL: <https://www.varnish-cache.org/trac/ticket/1791>
Varnish <https://varnish-cache.org/>
The Varnish HTTP Accelerator

_______________________________________________
varnish-bugs mailing list
varnish-bugs@varnish-cache.org
https://www.varnish-cache.org/lists/mailman/listinfo/varnish-bugs