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varnish-agent

Varnish Agent

Manual section:1
Authors: Kristian Lyngstøl
Yves Hwang
Date: 2013-02-06
Version: 2.2

SYNOPSIS

varnish-agent [-p directory] [-H directory] [-n name] [-c port]
              [-S file] [-T host:port] [-t timeout] [-h]
              [-P pidfile] [-V] [-u user] [-g group]
              [-z http://vac_register_url]
              [-K agentsecretfile] [-q] [-v]

DESCRIPTION

The varnish-agent is a small daemon meant to communicate with Varnish and other varnish-related services to allow remote control and monitoring of Varnish.

It listens to port 6085 by default. Try http://hostname:6085/html/ for the HTML front-end. All arguments are optional, but a password-file is required, see the -K option. The Varnish Agent will read other necessary options from the shm-log.

The Varnish Agent persists VCL changes to /var/lib/varnish-agent/ and maintains /var/lib/varnish-agent/boot.vcl.

OPTIONS

-K file Path to a file containing a single line representing the username and password required to authenticate. The file is the only required configuration of the agent. It should have a format of username:password.
-p directory Specify persistence directory. This is where VCL is stored. See varnish-agent -h to see the compiled in default.
-H directory Specify where html files are found. This directory will be accessible through /html/. The default provides a proof of concept front end.
-n name Specify the varnishd name. Should match the varnishd -n option. Amongst other things, this name is used to construct a path to the SHM-log file.
-S secretfile Path to the shared secret file, used to authenticate with varnishd.
-T hostport Hostname and port number for the management interface of varnishd.
-t timeout Timeout in seconds for talking to varnishd.
-c port Port number to listen for incomming connections. Defaults to 6085.
-P pidfile Write pidfile.
-d Run in foreground.
-V Print version.
-h Print help.
-u user User to run as. Defaults to nobody.
-g group Group to run as. Defaults to the primary group of the user.
-q Quiet mode. Only log/output warnings/errors.
-v Verbose mode. Be extra chatty, including all CLI chatter.
-z vac_register_url
 Specify the callback vac register url.

VARNISH CONFIGURATION

The agent does not require Varnish configuration changes for most changes. However, if you wish to boot Varnish up with the last known VCL, you may tell Varnish to use /var/lib/varnish-agent/boot.vcl. E.g by modifying /etc/sysconfig/varnish or /etc/default/varnish and changing the -f argument.

DESIGN

Keep it simple.

Everything is written as a module, and the goal is:

  • Close to 0 configuration
  • "Just works"
  • Maintainable
  • Generic
  • Stateless

SEE ALSO

  • varnish-cli(7)
  • varnishd(1)
  • varnishadm(1)
  • varnishlog(1)
  • varnishstat(1)
  • vcl(7)

HISTORY

The first generic WebUI for Varnish was written by Petter Knudsen of Linpro AS in 2009. This led to the creation of the Varnish Administration Console, built to manage multiple Varnish instances. Until 2013, the Varnish Administration Console used a minimal wrapper around the Varnish CLI language, requiring that the Varnish Administration Console knew the CLI language. This wrapper was known as the Varnish Agent version 1, written by Martin Blix Grydeland.

Development of the Varnish Agent version 2 begun in late 2012, with the first release in early 2013. Unlike the first version, it exposes a HTTP REST interface instead of trying to simulate a Varnish CLI session.

BUGS

Trying to "use" the boot VCL will regularly cause a "VCL deployed OK but not persisted". This is because the agent can only persist VCL if the VCL was stored through the agent - the boot vcl was not stored through the agent so there is no matching auto-generated VCL for it on disk. Workaround: Don't re-use the boot VCL.

The vlog module is limited. First of all, the limit it provides only works on unfiltered commands, and it's disregarded for tags. Secondly, the limit is a "head"-type limit now. It will give you the FIRST log entries, not the last matching. Additionally it only lists the content of the shmlog from the beginning of the file running up to the "here"-marker. If varnishd just wrapped around you will get minimal amount of feedback, while you'll get a truckload of feedback if you query the module right before varnishd wraps around.

Oh, and also, you may want to add some firewall rules. In case you didn't notice, there is currently 0 authorization of requests.

For more, see http://github.com/varnish/vagent2

COPYRIGHT

This document is licensed under the same license as the Varnish Agent itself. See LICENSE for details.

  • Copyright 2012-2013 Varnish Software AS