Hi all,
Just a quick update,
After changing the hitch to varnish connection from AF_UNIX to TCP,
rerunning the experiment with tcpdump active revealed that varnish
7.2.1 seemed to silently ignore HTTP/2 requests whenever my browser
chose that over HTTP/1.x . Turning off HTTP/2 in hitch seems to
make things work.
I'm still surprised that varnishd drops HTTP/2 over proxyv2 silently
with no logging that a connection was dropped, and in such a way that
web browsers interpret it as an empty page. Feels very similar to
my earlier issue that failure to bind to a specified listen address
was not shown to the sysadmin starting varnishd .
Now it's time to upgrade to 7.3.0 and improve the configuration.
On 2023-05-10 10:43, Jakob Bohm wrote:
On 2023-05-10 06:49, Guillaume Quintard wrote:
Hi Jakob,
(Sorry i didn't see that email sooner, it was in my spam folder)
Looking at the log, I'm not sure what varnish should be loud about :-)
204 is a success code, and more importantly it's generated by the
backend, so varnish is happily passing it along.
At the http level, everything looks about right, but I can guess from
your apparent irritation that something wrong one level up, let's try
to debug that.
What kind of response are you expecting, if not a 204? And maybe,
what is that endpoint supposed to do? Given that the method was GET,
and that there's no body, my only guess is that there's something
happening with the TeamCity-AgentSessionId header, maybe?
Is the 27 seconds processing time expected?
Expecting uncachable results that vary with time and are only
sometimes 204, and the response time is also somewhat unexpected, but
is not clearly logged (only a Varnish expert like you can decrypt that
it is 27 seconds). It is also unclear if Varnish is always receiving
those responses from the backend.
I also expected some other URLs in the log, but don't see them.
Maybe I should find another day to run the experiments again.
Cheers,
On Tue, May 9, 2023, 15:12 Jakob Bohm <[email protected]
<mailto:[email protected]>> wrote:
Dear Varnish mailing list,
When testing varnish as a reverse proxy for multiple services
including a local JetBrains TeamCity instance, requests to that
teamcity server get corrupted into "204 No Content" replies.
Once again, Varnish fails to say why it is refusing to do its job.
Any sane program should explicitly and loudly report any fatal error
that stops it working. Loudly means the sysadmin or other user
invoking the program receives the exaxt error message by default
instead of something highly indirect, hidden behind a debug option
or otherwisse highly non-obvious.
Here's a relevant clip from the VCL:
# Various top comments
vcl 4.1;
import std;
import proxy;
# Backend sending requests to the teamcity main server
backend teamcity {
.host = "2a01:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx";
.port = "8111";
}
# IP ranges allowed to access the build server and staging server
acl buildtrust {
"127.0.0.0"/8;
"::"/128;
"various others"/??;
}
# IP ranges allowed to attempt login to things that use our
common login
# database
acl logintrust {
"various others"/??;
}
sub vcl_recv {
# Happens before we check if we have this in cache already.
#
# Typically you clean up the request here, removing cookies
you
don't need,
# rewriting the request, etc.
if (proxy.is_ssl()) {
set req.http.Scheme = "https";
set req.http.ssl-version = proxy.ssl_version();
set req.http.X-Forwarded-Proto = "https";
set req.http.X-SSL-cipher = proxy.ssl_cipher();
std.log("TLS-SSL-VERSION: " + proxy.ssl_version());
} else {
set req.http.X-Forwarded-Proto = req.http.Scheme;
unset req.http.ssl-version;
unset req.http.X-SSL-cipher;
std.log("TLS-SSL-VERSION: none");
}
unset req.http.X-SSL-Subject;
unset req.http.X-SSL-Issuer;
unset req.http.X-SSL-notBefore;
unset req.http.X-SSL-notAfter;
unset req.http.X-SSL-serial;
unset req.http.X-SSL-certificate;
set req.http.X-Forwarded-For = client.ip;
call vcl_req_host;
if (req.url ~ "^/something") {
set req.backend_hint = be1;
} else if (req.url !~ "^/somethingelse" &&
!(client.ip ~ logintrust) &&
!(client.ip ~ buildtrust)) {
# Treat as unknown by redirecting to public website
if ((req.url ~ "^/yeatanother") ||
(req.url ~ "^/yetsomeother")) {
return (synth(752));
} else if (req.url ~ "^/yetsomethird") {
return (synth(753));
}
return (synth(751));
} else if (req.http.Scheme && req.http.Scheme != "https") {
# See example at
https://www.varnish-software.com/developers/tutorials/redirect/
return (synth(750));
} else if (req.url ~ "^/somethingelse") {
set req.backend_hint = be1;
} else if (req.url ~ "^/somethingfourth") {
set req.backend_hint = be2;
} else if (req.url ~ "^/somethingfifth") {
set req.backend_hint = be2;
} else if (!(client.ip ~ buildtrust)) {
# Treat as unknown by redirecting to public website
if ((req.url ~ "^/yeatanother") ||
(req.url ~ "^/yetsomeother")) {
return (synth(752));
} else if (req.url ~ "^/yetsomethird") {
return (synth(753));
}
return (synth(751));
} else if (req.url ~ "^/teamcity") {
set req.backend_hint= teamcity;
return (pass);
# } else if (req.http.host ~ "^somethingsixths") {
# set req.backend_hint= be4;
} else {
set req.backend_hint = be5;
}
call vcl_req_method;
call vcl_req_authorization;
call vcl_req_cookie;
return (hash);
}
sub vcl_backend_response {
# Happens after we have read the response headers from the
backend.
#
# Here you clean the response headers, removing silly
Set-Cookie
headers
# and other mistakes your backend does.
# The Java webserver in teamcity is incompatible with varnish
connection
# pooling
if (beresp.backend == teamcity) {
if (beresp.http.Connection &&
beresp.http.Connection !~ "keep-alive") {
set beresp.http.Connection += ", close";
} else {
set beresp.http.Connection = "close";
}
}
}
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
First 43 lines of varnishlog -v 2>&1
* << BeReq >> 9
- 9 Begin b bereq 8 pass
- 9 VCL_use b boot
- 9 Timestamp b Start: 1681484803.177212 0.000000
0.000000
- 9 BereqMethod b GET
- 9 BereqURL b
/teamcity/app/agents/v1/commands/next
- 9 BereqProtocol b HTTP/1.1
- 9 BereqHeader b TeamCity-AgentSessionId:
L6juFAAt1awJDt6UKToPIxQq7wpBF89C
- 9 BereqHeader b User-Agent: TeamCity Agent 2021.2.3
- 9 BereqHeader b Host: vmachine.example.com
<http://vmachine.example.com>
- 9 BereqHeader b Via: 1.1 vmachine (Varnish/7.2)
- 9 BereqHeader b Scheme: https
- 9 BereqHeader b ssl-version: TLSv1.3
- 9 BereqHeader b X-Forwarded-Proto: https
- 9 BereqHeader b X-SSL-cipher: TLS_AES_256_GCM_SHA384
- 9 BereqHeader b X-Forwarded-For: 192.168.2.112
- 9 BereqHeader b X-Varnish: 9
- 9 VCL_call b BACKEND_FETCH
- 9 VCL_return b fetch
- 9 Timestamp b Fetch: 1681484803.177227 0.000014
0.000014
- 9 Timestamp b Connected: 1681484803.177603
0.000390
0.000375
- 9 BackendOpen b 24 teamcity
2a01:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx 8111
2a01:yyyy:yyyy:yyyy::yyyy
59548 connect
- 9 Timestamp b Bereq: 1681484803.177645 0.000432
0.000042
- 9 BerespReason b No Content
- 9 Timestamp b Beresp: 1681484830.672487 27.495274
27.494842
- 9 BerespProtocol b HTTP/1.1
- 9 BerespStatus b 204
- 9 BerespReason b No Content
- 9 BerespHeader b TeamCity-Node-Id: MAIN_SERVER
- 9 BerespHeader b Date: Fri, 14 Apr 2023 15:07:10 GMT
- 9 VCL_call b BACKEND_RESPONSE
- 9 BerespHeader b Connection: close
- 9 VCL_return b deliver
- 9 Timestamp b Process: 1681484830.672563 27.495350
0.000075
- 9 Filters b
- 9 Storage b malloc Transient
- 9 Fetch_Body b 0 none -
- 9 BackendClose b 24 teamcity close Backend/VCL
requested
close
- 9 Timestamp b BerespBody: 1681484830.672926
27.495713
0.000362
- 9 Length b 0
- 9 BereqAcct b 345 0 345 85 0 85
- 9 End b
Enjoy
Jakob
--
Jakob Bohm, CIO, Partner, WiseMo A/S. https://www.wisemo.com
Transformervej 29, 2860 Søborg, Denmark. Direct +45 31 13 16 10
This public discussion message is non-binding and may contain errors.
WiseMo - Remote Service Management for PCs, Phones and Embedded
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