</varlistentry>
<varlistentry>
<term><filename>man</filename></term>
+ <listitem>
+ <para>Additional man pages.</para>
+ </listitem>
</varlistentry>
</variablelist>
</listitem>
<section>
<title>Principles of operation</title>
+ <para>Lorem ipsum dolor sit amet</para>
</section>
<section>
<title>Subsystems</title>
+ <section>
+ <title>The management interface</title>
+
+ <para>The management interface allows a person or process to
+ control certain aspects of the accelerator while it is
+ running, such as inspecting and setting run-time parameters,
+ starting and stopping the child process, and purging
+ objects.</para>
+
+ <para>The commands accepted by the management interface fall
+ in two categories: management commands and child commands.
+ The former are handled by the management (parent) process,
+ while the latter are passed unmodified to the child process
+ and handled there.</para>
+
+ <para>The management interface uses an extremely simple
+ text-based protocol described below.</para>
+
+ <para>The user sends a single line of text consisting of one
+ or more words separated by linear whitespace, terminated by a
+ newline character. Words which contain linear whitespace must
+ be placed in double quotes; newline characters must be sent as
+ <literal>\n</literal>, backslash characters as
+ <literal>\\</literal> and double quote characters as
+ <literal>\"</literal>.</para>
+
+ <para>The first word sent by the client is the command name,
+ and subsequent words are command arguments.</para>
+
+ <para>The management process responds with a line consisting
+ of a three-digit status code, linear whitespace, a byte count,
+ and a newline character. If the byte count is non-zero, this
+ line is followed by that many bytes of additional data, plus a
+ newline character.</para>
+
+ <para>Status code 200 indicates success; all other codes
+ indicate some kind of failure. Status codes between 100 and
+ 199 indicate a syntax error, an unknown command, or issues
+ with the number or nature of the arguments. Status codes
+ between 300 and 399 indicate a failure to carry out the
+ requested operation. The status code 400 indicates a
+ communications error.</para>
+ </section>
</section>
<section>
<title>Data structures</title>
+ <para>Lorem ipsum dolor sit amet</para>
</section>
</section>
<section>
<title>varnishlog</title>
+ <para>Lorem ipsum dolor sit amet</para>
</section>
<section>
<title>varnishncsa</title>
+ <para>Lorem ipsum dolor sit amet</para>
</section>
</section>
<section>
<title>varnishstat</title>
+ <para>Lorem ipsum dolor sit amet</para>
</section>
<section>
<title>varnishhist</title>
+ <para>Lorem ipsum dolor sit amet</para>
</section>
<section>
<title>varnishtop</title>
+ <para>Lorem ipsum dolor sit amet</para>
</section>
</section>
<section>
<title>The test framework</title>
+ <para>Lorem ipsum dolor sit amet</para>
</section>
<section>
<title>Plugins</title>
- <para>The <filename>trunk/varnish-tools</filename> directory in
+ <para>The <filename>trunk/varnish-tools/</filename> directory in
the Varnish repository contains Varnish plugins for several
popular system monitoring and administration frameworks.</para>
<section>
<title>Munin</title>
+ <para>Munin, named for one of the two ravens that in Norse
+ tradition sit on the shoulders of Odin, father of the gods, is a
+ monitoring and graphing tool built on top of Tobi Oetiker's
+ RRDtool and maintained largely by Linpro.</para>
+
+ <para>The Varnish Munin plugin is written in Perl and resides in
+ <filename>trunk/varnish-tools/munin/</filename>. It can report
+ on any statistic (called <emphasis>aspects</emphasis>) stored in
+ the shared memory log, and can easily be extended to also report
+ values computed from these statistics (<emphasis>derived
+ aspects</emphasis>).</para>
+
+ <para>When run, the plugin first invokes
+ <command>varnishstat</command>. Using the first column as keys,
+ it registers each available statistic in the
+ <varname>%ASPECTS</varname> hash, and stores their values in the
+ <varname>%varnishstat</varname> hash. It then verifies that the
+ requested aspect matches one of the items in
+ <varname>%ASPECTS</varname>, i.e. one of the statistics reported
+ by <command>varnishstat</command> or a predefined derived
+ aspect. Finally, it either looks up or computes the requested
+ value, and prints it to <varname>stdout</varname> in the format
+ expected by Munin.</para>
+
+ <para>Aspects are of one of three types:
+ <literal>count</literal> (a monotonically increasing counter),
+ <literal>gauge</literal> (an instantaneous measurement) and
+ <literal>percent</literal> (a fraction expressed as a
+ percentage). The first two are used for automatically created
+ aspects (i.e. everything <command>varnishstat</command>
+ reports), while the third is used only for predefined derived
+ aspects.</para>
+
+ <para>A <literal>count</literal> or <literal>gauge</literal>
+ aspect has a <literal>value</literal> which is either a key in
+ <varname>%varnishstat</varname> or a reference to an array
+ representing an expression; the first element of the array is an
+ arithmetic operator, and subsequent elements are the terms
+ (which can themselves be references to expression
+ arrays).</para>
+
+ <para>A <literal>percent</literal> aspect has one or more
+ values; if it has more than one, Munin will stack them. Each
+ value has a <literal>numerator</literal> and a
+ <literal>denominator</literal>, each of which is, as above,
+ either a key in <varname>%varnishstat</varname> or an
+ expression.</para>
+
+ <para>When adding or modifying derived aspects, care should be
+ taken not to create unnecessary inconsistencies between this
+ plugin and the Nagios plugin described in the next
+ section.</para>
</section>
<section>
<title>Nagios</title>
+ <para>Nagios is a web-based host and network monitoring tool.
+ The major difference between Nagios and Munin is that while
+ Munin records statistics and creates graphs, Nagios primarily
+ wants to know whether a particular part of the system has failed
+ or is about to fail.</para>
+
+ <para>The Varnish Nagios plugin is written in C and resides in
+ <filename>trunk/varnish-tools/nagios/</filename>. It can report
+ any statistic stored in the shared memory log. It can also
+ fairly easily be extended to report computed statistics.</para>
+
+ <!-- XXX more -->
+
+ <para>When adding or modifying parameters, care should be taken
+ not to create unnecessary inconsistencies between this plugin
+ and the Munin plugin described in the previous section.</para>
</section>
<section>
<title>Webmin</title>
+ <para>Webmin is a web-based system configuration and
+ administration tool for Unix-like systems.</para>
+
+ <para>The Varnish Webmin plugin is written in Perl and resides
+ in <filename>trunk/varnish-tools/webmin/</filename>. It can
+ perform all of the functions that are available through the
+ management process's command-line interface.</para>
+
+ <!-- XXX more -->
</section>
</section>
<section>
<title>varnishadm</title>
+ <para>Lorem ipsum dolor sit amet</para>
</section>
<section>
<title>varnishreplay</title>
+ <para>Lorem ipsum dolor sit amet</para>
</section>
<section>
<title>fetcher</title>
+ <para>Lorem ipsum dolor sit amet</para>
</section>
</section>
</article>
projects / varnish / commitdiff