Repository
Munin (master)
Last change
2018-03-29
Graph Categories
Family
auto
Capabilities
Language
Perl
License
GPL-2.0-only
Authors

varnish_

Name

varnish_ - Munin plugin to monitor various aspects of varnish

Applicable Systems

Varnish 2.0 or newer with varnishstat

Configuration

The plugin needs to be able to execute varnishstat.

The configuration section shows the defaults [varnish_*] env.varnishstat varnishstat env.name

env.varnishstat can be a full path to varnishstat if it’s not in the path already.

env.name is blank (undefined) by default and can be used to specify a -n name argument to varnish if multiple instances are running on the same server.

A few aspects are not linked by default. They are marked as ‘DEBUG’ => ‘yes’ (or any other value). They are:

data_structures, vcl_and_bans, lru, objects_per_objhead, obj_sendfile_vs_write, losthdr, esi, hcb, shm, shm_writes, overflow, session, session_herd

You can link them yourself with something like this:

ln -s /usr/share/munin/plugins/varnish_ \
  /etc/munin/plugins/varnish_data_structures

Interpretation

Each graph uses data from varnishstat.

Magic Markers

#%# family=auto
#%# capabilities=autoconf suggest

Bugs

The hit_rate graph requires munin r2040 or newer to display correctly.

Patches-To

Please send patches to Kristian Lyngstol kristian@bohemians.org and/or varnish-misc@varnish-cache.org for significant changes. Munin SVN is the authoritative repository for this plugin.

Author

Kristian Lyngstol kristian@bohemians.org

License

GPLv2

#!/usr/bin/perl
#
# varnish_ - Munin plugin to for Varnish
# Copyright (C) 2009  Redpill Linpro AS
#
# Author: Kristian Lyngstol <kristian@bohemians.org>
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License along
# with this program; if not, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.

=head1 NAME

varnish_ - Munin plugin to monitor various aspects of varnish

=head1 APPLICABLE SYSTEMS

Varnish 2.0 or newer with varnishstat

=head1 CONFIGURATION

The plugin needs to be able to execute varnishstat.

The configuration section shows the defaults
  [varnish_*]
     env.varnishstat varnishstat
     env.name

env.varnishstat can be a full path to varnishstat if it's
not in the path already.

env.name is blank (undefined) by default and can be used to specify a -n
name argument to varnish if multiple instances are running on the same
server.

A few aspects are not linked by default. They are marked as
'DEBUG' => 'yes' (or any other value). They are:

data_structures, vcl_and_bans, lru, objects_per_objhead,
obj_sendfile_vs_write, losthdr, esi, hcb, shm, shm_writes, overflow,
session, session_herd

You can link them yourself with something like this:

  ln -s /usr/share/munin/plugins/varnish_ \
    /etc/munin/plugins/varnish_data_structures

=head1 INTERPRETATION

Each graph uses data from varnishstat.

=head1 MAGIC MARKERS

 #%# family=auto
 #%# capabilities=autoconf suggest

=head1 BUGS

The hit_rate graph requires munin r2040 or newer to display
correctly.

=head1 PATCHES-TO

Please send patches to Kristian Lyngstol <kristian@bohemians.org>
and/or varnish-misc@varnish-cache.org for significant changes. Munin SVN
is the authoritative repository for this plugin.

=head1 AUTHOR

Kristian Lyngstol <kristian@bohemians.org>

=head1 LICENSE

GPLv2

=cut


use strict;

use English qw( -no_match_vars );
eval { require XML::Parser; XML::Parser->import(); };
my $has_xml_parser = $EVAL_ERROR ? 0 : 1;

# Set to 1 to enable output when a variable is defined in a graph but
# omitted because it doesn't exist in varnishstat.
my $DEBUG = 0;

# Set to 1 to ignore 'DEBUG' and suggest all available aspects.
my $FULL_SUGGEST = 0;

# Varnishstat executable. Include full path if it's not in your path.
my $varnishstatexec = exists $ENV{'varnishstat'} ? $ENV{'varnishstat'} : "varnishstat";

# For multiple instances
my $varnishname = exists $ENV{'name'} ? $ENV{'name'} : undef;

my $self; # Haha, myself, what a clever pun.

# Parameters that can be defined on top level of a graph. Config will print
# them as "graph_$foo $value\n"
my @graph_parameters = ('title','total','order','scale','vlabel','args');

# Parameters that can be defined on a value-to-value basis and will be
# blindly passed to config. Printed as "$fieldname.$param $value\n".
#
# 'label' is hardcoded as it defaults to a varnishstat-description if not
# set.
my @field_parameters = ('graph', 'min', 'max', 'draw', 'cdef', 'warning',
			'colour', 'info', 'type');

# Varnishstat data is stored here. Example
# ('n_vbe' => { 'value' => '124', 'description'=>...,'flag'=>... }, SMA =>
# { s0 => { 'value' => '...', 'flag'=> '...' },'Transient' => ...})
# Both dynamic and static counters are kept here.
#
# Notes:
#  - The 'flag' field for a counter is in RRD-dialect, not varnishstat
my %data;

# Data structure that defines all possible graphs (aspects) and how they
# are to be plotted. Every top-level entry is a graph/aspect. Each
# top-level graph MUST have title set and 'values'.
#
# The 'values' hash must have at least one value definition. The actual
# value used is either fetched from varnishstat based on the value-name, or
# if 'rpn' is defined: calculated. 'type' SHOULD be set.
#
# Graphs with 'DEBUG' set to anything is omitted from 'suggest'.
#
# 'rpn' on values allows easy access to graphs consisting of multiple
# values from varnishstat. (Reverse polish notation). The RPN
# implementation only accepts +-*/ and varnishstat-values.
#
# With the exception of 'label', which is filled with the
# varnishstat-description if left undefined, any value left undefined will
# be left up to Munin to define/ignore/yell about.
#
# For dynamic counters, the values listed need to specify a counter and
# family. This will plot the specified counter for each identity within
# that family. Example: family of SMA, counter c_fail. This will create a
# c_fail-counter for each of the SMA-identities (e.g: Transient, s0, etc).
# For dynamic graphs, the value-name is only used to identify the data
# point, and does not relate to any varnishstat data as that is set by
# family/counter.
#
# Note that dynamic counters fetch the type from the XML and things like
# min/max are currently not supported (and silently ignored).
#
# See munin documentation or rrdgraph/rrdtool for more information.
my %ASPECTS = (
	'request_rate' => {
		'title' => 'Request rates',
		'order' => 'cache_hit cache_hitpass cache_miss '
			 . 'backend_conn backend_unhealthy '
			 . 'client_req client_conn' ,
		'values' => {
			# Version 3 only
			'client_conn' => {
				'type' => 'DERIVE',
				'min' => '0',
				'colour' => '444444',
				'graph' => 'ON'
			},
			'client_req' => {
				'type' => 'DERIVE',
				'colour' => '111111',
				'min' => '0'
			},
			'cache_hit' => {
				'type' => 'DERIVE',
				'draw' => 'AREA',
				'colour' => '00FF00',
				'min' => '0'
			},
			'cache_hitpass' => {
				'info' => 'Hitpass are cached passes: An '
					. 'entry in the cache instructing '
					. 'Varnish to pass. Typically '
					. 'achieved after a pass in '
					. 'vcl_fetch.',
				'type' => 'DERIVE',
				'draw' => 'STACK',
				'colour' => 'FFFF00',
				'min' => '0'
			},
			'cache_miss' => {
				'type' => 'DERIVE',
				'colour' => 'FF0000',
				'draw' => 'STACK',
				'min' => '0'
			},
			'backend_conn' => {
				'type' => 'DERIVE',
				'colour' => '995599',
				'min' => '0'
			},
			'backend_unhealthy' => {
				'type' => 'DERIVE',
				'min' => '0',
				'colour' => 'FF55FF'
			},
			's_pipe' => {
				'type' => 'DERIVE',
				'min' => '0',
				'colour' => '1d2bdf'
			},
			's_pass' => {
				'type' => 'DERIVE',
				'min' => '0',
				'colour' => '785d0d'
			},
			# Version 4 only
			'sess_conn' => {
				'type' => 'DERIVE',
				'min' => '0',
				'colour' => '444444',
				'graph' => 'ON'
			}
		}
	},
	'hit_rate' => {
		'title' => 'Hit rates',
		'order' => 'client_req cache_hit cache_miss '
			 . 'cache_hitpass' ,
		'vlabel' => '%',
		'args' => '-u 100 --rigid',
		'scale' => 'no',
		'values' => {
			'client_req' => {
				'type' => 'DERIVE',
				'min' => '0',
				'graph' => 'off'
			},
			'cache_hit' => {
				'type' => 'DERIVE',
				'min' => '0',
				'draw' => 'AREA',
				'cdef' => 'cache_hit,client_req,/,100,*'
			},
			'cache_miss' => {
				'type' => 'DERIVE',
				'draw' => 'STACK',
				'min' => '0',
				'cdef' => 'cache_miss,client_req,/,100,*'
			},
			'cache_hitpass' => {
				'type' => 'DERIVE',
				'draw' => 'STACK',
				'min' => '0',
				'cdef' => 'cache_hitpass,client_req,/,100,*'
			},
		}
	},
	'backend_traffic' => {
		'title' => 'Backend traffic',
		'values' => {
			'backend_conn' => {
				'type' => 'DERIVE',
				'min' => '0'
			},
			'backend_unhealthy' => {
				'type' => 'DERIVE',
				'min' => '0',
				'warning' => ':1'
			},
			'backend_busy' => {
				'type' => 'DERIVE',
				'min' => '0'
			},
			'backend_fail' => {
				'type' => 'DERIVE',
				'min' => '0'
			},
			'backend_reuse' => {
				'type' => 'DERIVE',
				'min' => 0
			},
			'backend_recycle' => {
				'type' => 'DERIVE',
				'min' => 0
			},
			'backend_unused' => {
				'type' => 'DERIVE',
				'min' => '0'
			},
			'backend_req' => {
				'type' => 'DERIVE',
				'min' => '0'
			}
		}
	},
	'objects' => {
		'title' => 'Number of objects',
		'values' => {
			'n_object' => {
				'type' => 'GAUGE',
				'label' => 'Number of objects'
			},
			# Version 3 only
			'n_objcore' => {
				'type' => 'GAUGE',
				'label' => 'Number of object cores'
			},
			# Version 4 only
			'n_objectcore' => {
				'type' => 'GAUGE',
				'label' => 'Number of object cores'
			},
			'n_objecthead' => {
				'type' => 'GAUGE',
				'label' => 'Number of object heads',
				'info' => 'Each object head can have one '
					. 'or more object attached, '
					. 'typically based on the Vary: header'
			}
		}
	},
	'transfer_rates' => {
		'title' => 'Client response transfer rates',
		'order' => 's_bodybytes s_hdrbytes',
		'args' => '-l 0',
		'vlabel' => 'bit/s',
		'values' => {
			# These are the entries needed for Version 3
			's_hdrbytes' => {
				'type' => 'DERIVE',
				'label' => 'Header traffic',
				'draw' => 'STACK',
				'min' => '0',
				'info' => 'HTTP Header traffic. TCP/IP '
					. 'overhead is not included.',
				'cdef' => 's_hdrbytes,8,*'
			},
			's_bodybytes' => {
				'type' => 'DERIVE',
				'draw' => 'AREA',
				'label' => 'Body traffic',
				'min' => '0',
				'cdef' => 's_bodybytes,8,*'
			},
			# These are the entries needed for Version 4
			's_resp_hdrbytes' => {
				'type' => 'DERIVE',
				'label' => 'Header traffic',
				'draw' => 'STACK',
				'min' => '0',
				'info' => 'HTTP Header traffic. TCP/IP '
					. 'overhead is not included.',
				'cdef' => 's_resp_hdrbytes,8,*'
			},
			's_resp_bodybytes' => {
				'type' => 'DERIVE',
				'draw' => 'AREA',
				'label' => 'Body traffic',
				'min' => '0',
				'cdef' => 's_resp_bodybytes,8,*'
			}
		}
	},
	'threads' => {
		'title' => 'Thread status',
		'values' => {
			# These are the entries needed for Version 3
			'n_wrk' => {
				'type' => 'GAUGE',
				'min' => '0',
				'warning' => '1:'
			},
			'n_wrk_create' => {
				'type' => 'DERIVE',
				'min' => '0'
			},
			'n_wrk_failed' => {
				'type' => 'DERIVE',
				'min' => '0',
				'warning' => ':0'
			},
			'n_wrk_max' => {
				'type' => 'DERIVE',
				'min' => '0'
			},
			'n_wrk_overflow' => {
				'type' => 'DERIVE',
				'min' => '0'
			},
			'n_wrk_drop' => {
				'type' => 'DERIVE',
				'min' => '0',
				'warning' => ':0'
			},
			# These are the entries needed for Version 4
			'threads' => {
				'type' => 'GAUGE',
				'min' => '0',
				'warning' => '1:'
			},
			'threads_created' => {
				'type' => 'DERIVE',
				'min' => '0'
			},
			'threads_failed' => {
				'type' => 'DERIVE',
				'min' => '0',
				'warning' => ':0'
			},
			'threads_limited' => {
				'type' => 'DERIVE',
				'min' => '0'
			},
			'threads_destroyed' => {
				'type' => 'DERIVE',
				'min' => '0'
			},
		}
	},
	'memory_usage' => {
		'title' => 'Memory usage',
		'args' => '--base 1024',
		'vlabel' => 'bytes',
		'values' => {
			'sm_balloc' => {
				'type' => 'GAUGE',
			},
			'sma_nbytes' => {
				'type' => 'GAUGE',
			},
			'sms_nbytes' => {
				'type' => 'GAUGE',
			},
			'SMA_1' => {
				'counter' => 'g_bytes',
				'family' => 'SMA',
			},
			'SMA_2' => {
				'counter' => 'g_space',
				'family' => 'SMA',
			},
			'SMF_1' => {
				'counter' => 'g_bytes',
				'family' => 'SMF',
			},
			'SMF_2' => {
				'counter' => 'g_space',
				'family' => 'SMF',
			}
		}
	},
	'uptime' => {
		'title' => 'Varnish uptime',
		'vlabel' => 'days',
		'scale' => 'no',
		'values' => {
			'uptime' => {
				'type' => 'GAUGE',
				'cdef' => 'uptime,86400,/'
			}
		}
	},
	'objects_per_objhead' => {
		'title' => 'Objects per objecthead',
		'DEBUG' => 'yes',
		'values' => {
			'obj_per_objhead' => {
				'type' => 'GAUGE',
				'label' => 'Objects per object heads',
				'rpn' => [ 'n_object','n_objecthead','/' ]
			}
		}
	},
	'losthdr' => {
		'title' => 'HTTP Header overflows',
		'DEBUG' => 'yes',
		'values' => {
			'losthdr' => {
				'type' => 'DERIVE',
				'min' => '0'
			}
		}
	},
	'obj_sendfile_vs_write' => {
		'title' => 'Objects delivered with sendfile() versus '
			 . 'write()',
		'DEBUG' => 'yes',
		'values' => {
			'n_objsendfile' => {
				'type' => 'DERIVE',
				'min' => '0',
			},
			'n_objwrite' => {
				'type' => 'DERIVE',
				'min' => '0'
			}
		}
	},
	'hcb' => {
		'title' => 'Critbit data',
		'DEBUG' => 'yes',
		'values' => {
			'hcb_nolock' => {
				'type' => 'DERIVE',
				'min' => '0'
			},
			'hcb_lock' => {
				'type' => 'DERIVE',
				'min' => '0'
			},
			'hcb_insert' => {
				'type' => 'DERIVE',
				'min' => '0'
			}
		}
	},
	'esi' => {
		'title' => 'ESI',
		'DEBUG' => 'yes',
		'values' => {
			'esi_parse' => {
				'type' => 'DERIVE',
				'min' => '0'
			},
			'esi_errors' => {
				'type' => 'DERIVE',
				'min' => '0'
			}
		}
	},
	'objoverflow' => {
		'title' => 'Objects overflowing workspace',
		'DEBUG' => 'yes',
		'values' => {
			'n_objoverflow' => {
				'type' => 'DERIVE',
				'min' => '0'
			}
		}
	},
	'session' => {
		'title' => 'Sessions',
		'DEBUG' => 'yes',
		'values' => {
			'sess_closed' => {
				'type' => 'DERIVE',
				'min' => '0'
			},
			'sess_pipeline' => {
				'type' => 'DERIVE',
				'min' => '0'
			},
			'sess_readahead' => {
				'type' => 'DERIVE',
				'min' => '0'
			},
			'sess_linger' => {
				'type' => 'DERIVE',
				'min' => '0'
			}
		}
	},
	'session_herd' => {
		'title' => 'Session herd',
		'DEBUG' => 'yes',
		'values' => {
			'sess_herd' => {
				'type' => 'DERIVE',
				'min' => '0'
			}
		}
	},
	'shm_writes' => {
		'title' => 'SHM writes and records',
		'DEBUG' => 'yes',
		'values' => {
			'shm_records' => {
				'type' => 'DERIVE',
				'min' => '0'
			},
			'shm_writes' => {
				'type' => 'DERIVE',
				'min' => '0'
			}
		}
	},
	'shm' => {
		'title' => 'Shared memory activity',
		'DEBUG' => 'yes',
		'values' => {
			'shm_flushes' => {
				'type' => 'DERIVE',
				'min' => '0'
			},
			'shm_cont' => {
				'type' => 'DERIVE',
				'min' => '0'
			},
			'shm_cycles' => {
				'type' => 'DERIVE',
				'min' => '0'
			}
		}
	},
	'allocations' => {
		'title' => 'Memory allocation requests',
		'DEBUG' => 'yes',
		'values' => {
			'sm_nreq' => {
				'type' => 'DERIVE',
				'min' => '0'
			},
			'sma_nreq' => {
				'type' => 'DERIVE',
				'min' => '0'
			},
			'sms_nreq' => {
				'type' => 'DERIVE',
				'min' => '0'
			}
		}
	},
	'vcl_and_bans' => {
		'title' => 'VCL and bans',
		'DEBUG' => 'yes',
		'values' => {
			'n_backend' => {
				'type' => 'GAUGE'
			},
			'n_vcl' => {
				'type' => 'DERIVE',
				'min' => '0'
			},
			'n_vcl_avail' => {
				'type' => 'DERIVE',
				'min' => '0'
			},
			'n_vcl_discard' => {
				'type' => 'DERIVE',
				'min' => '0'
			},
			'n_ban' => {
				'type' => 'GAUGE'
			},
			'n_ban_add' => {
				'type' => 'DERIVE',
				'min' => '0'
			},
			'n_ban_retire' => {
				'type' => 'DERIVE',
				'min' => '0'
			},
			'n_ban_obj_test' => {
				'type' => 'DERIVE',
				'min' => '0'
			},
			'n_ban_re_test' => {
				'type' => 'DERIVE',
				'min' => '0'
			},
			'n_ban_dups' => {
				'type' => 'DERIVE',
				'min' => '0'
			}
		}
	},
	'expunge' => {
		'title' => 'Object expunging',
		'values' => {
			'n_expired' => {
				'type' => 'DERIVE',
				'min' => '0'
			},
			'n_lru_nuked' => {
				'type' => 'DERIVE',
				'min' => '0'
			}
		}
	},
	'lru' => {
		'title' => 'LRU activity',
		'DEBUG' => 'yes',
		'values' => {
			'n_lru_saved' => {
				'type' => 'DERIVE',
				'min' => '0'
			},
			'n_lru_moved' => {
				'type' => 'DERIVE',
				'min' => '0'
			}
		}
	},
	'bad' => {
		'title' => 'Misbehavior',
		'values' => {
			'SMA_1' => {
				'counter' => 'c_fail',
				'family' => 'SMA',
			},
			'SMF_1' => {
				'counter' => 'c_fail',
				'family' => 'SMF',
			},
			'client_drop' => {
				'type' => 'DERIVE'
			},
			'backend_unhealthy' => {
				'type' => 'DERIVE'
			},
			'fetch_failed' => {
				'type' => 'DERIVE'
			},
			'backend_busy' => {
				'type' => 'DERIVE'
			},
			'n_wrk_failed' => {
				'type' => 'DERIVE'
			},
			'n_wrk_max' => {
				'type' => 'DERIVE'
			},
			'n_wrk_drop' => {
				'type' => 'DERIVE'
			},
			'n_wrk_lqueue' => {
				'type' => 'GAUGE'
			},
			'losthdr' => {
				'type' => 'DERIVE'
			},
			'n_objoverflow' => {
				'type' => 'DERIVE'
			},
			'esi_errors' => {
				'type' => 'DERIVE'
			},
			'esi_warnings' => {
				'type' => 'DERIVE'
			},
			'client_drop_late' => {
				'type' => 'DERIVE'
			},
			'accept_fail' => {
				'type' => 'DERIVE'
			},
			# Version 4 additions
			'threads_failed' => {
				'type' => 'DERIVE'
			},
			'sess_drop' => {
				'type' => 'DERIVE'
			},
			'sess_fail' => {
				'type' => 'DERIVE'
			},
			'threads_limited' => {
				'type' => 'DERIVE'
			}
		}
	},
	'data_structures' => {
		'DEBUG' => 'YES',
		'title' => 'Data structure sizes',
		'values' => {
			'n_srcaddr' => {
				'type' => 'GAUGE'
			},
			'n_srcaddr_act' => {
				'type' => 'GAUGE'
			},
			'n_sess_mem' => {
				'type' => 'GAUGE'
			},
			'n_sess' => {
				'type' => 'GAUGE'
			},
			'n_smf' => {
				'type' => 'GAUGE'
			},
			'n_smf_frag' => {
				'type' => 'GAUGE'
			},
			'n_smf_large' => {
				'type' => 'GAUGE'
			},
			'n_vbe_conn' => {
				'type' => 'GAUGE'
			},
			'n_bereq' => {
				'type' => 'GAUGE'
			}
		}
	}
);

################################
# Various helper functions     #
################################

# Translate $_[0] from varnish' internal types (flags) to munin/rrd
# variants (e.g: from 'i' to GAUGE). Returns the result.
sub translate_type
{
	my $d = $_[0];
	if ($d eq "i") {
		$d = "GAUGE";
	} elsif ($d eq "a") {
		$d = "DERIVE";
	}
	return $d;
}

# Print the value of a two-dimensional hash if it exist.
# Returns false if non-existent.
#
# Output is formatted for plugins if arg4 is blank, otherwise arg4 is used
# as the title/name of the field (ie: arg4=graph_title).
sub print_if_exist
{
	my %values = %{$_[0]};
	my $value = $_[1];
	my $field = $_[2];
	my $title = "$value.$field";
	if (defined($_[3])) {
		$title = $_[3];
	}
	if (defined($values{$value}{$field})) {
		print "$title $values{$value}{$field}\n";
	} else {
		return 0;
	}
}

# Create a output-friendly name
sub normalize_name
{
	my $name = $_[0];
	$name =~ s/[^a-zA-Z0-9]/_/g;
	return $name;
}

# Braindead RPN: +,-,/,* will pop two items from @stack, and perform
# the relevant operation on the items. If the item in the array isn't one
# of the 4 basic math operations, a value from varnishstat is pushed on to
# the stack. IE: 'client_req','client_conn','/' will leave the value of
# "client_req/client_conn" on the stack.
#
# If only one item is left on the stack, it is printed. Otherwise, an error
# message is printed.
sub rpn
{
	my @stack;
	my $left;
	my $right;
	foreach my $item (@{$_[0]}) {
		if ($item eq "+") {
			$right = pop(@stack);
			$left = pop(@stack);
			push(@stack,$left+$right);
		} elsif ($item eq "-") {
			$right = pop(@stack);
			$left = pop(@stack);
			push(@stack,$left-$right);
		} elsif ($item eq "/") {
			$right = pop(@stack);
			$left = pop(@stack);
			push(@stack,$left/$right);
		} elsif ($item eq "*") {
			$right = pop(@stack);
			$left = pop(@stack);
			push(@stack,$left*$right);
		} else {
			push(@stack,int($data{$item}{'value'}));
		}
	}
	if (@stack > 1)
	{
		print STDERR "RPN error: Stack has more than one item left.\n";
		print STDERR "@stack\n";
		exit 255;
	}
	print "@stack";
	print "\n";
}

# Bail-function.
sub usage
{
	if (@_) {
		print STDERR "@_" . "\n\n";
	}
	print STDERR "Known arguments: suggest, config, autoconf.\n";
	print STDERR "Run with suggest to get a list of known aspects.\n";
	exit 1;
}

################################
# XML Parsing                  #
################################
# The following code is for parsing varnishstat -x. While %data should be
# stable, the following bits can easily be replaced with anything (json, an
# other xml-parser, magic, etc)
#
# The basic concept is simple enough. Only worry about stuff inside
# <state>. Updating %state on each new data field, and commit it to %data
# when </state> is seen.
#
# We do use translate_type() on the 'flag' field.


# Internal state for the XML parsing
my %state = (
	'stat' => 0,     # inside <stat> or not
	'field' => 'none', # <name>, <value>, <stat>, etc.
	'values' => ()
);

# Reset the state of XML, mainly used for end-elements.
sub xml_reset_state() {
	$state{'stat'} = '0';
	$state{'field'} = 'none';
	$state{'values'} = ();
}

# Callback for data entry. Cleans leading whitespace and updates state.
sub xml_characters {
	my $d = $_[1];
	if ($state{'stat'} == 0) {
		return;
	}
	$d =~ s/^\s*$//g;
	if ($d eq "") {
		return;
	}
	$state{'values'}{$state{'field'}} = $d;
}

# Store the current state in %data. Issued at </stat>
# Note that 'flag' is translated to RRD-equivalents here.
sub xml_commit_state
{
	my $type;
	my $name;
	if ($state{'values'}{'name'} =~ /\./) {
		# since Varnish 5.2 the 'name' field includes a 'type' prefix ("type.name")
		($type, $name) = split(/\./, $state{'values'}{'name'}, 2);
	} else {
		$name = $state{'values'}{'name'};
		$type = $state{'values'}{'type'};
	}
	my $ident = $state{'values'}{'ident'};

	foreach my $key (keys %{$state{'values'}}) {
		my $data = $state{'values'}{$key};
		if ($key eq 'flag') {
			$data = translate_type($data);
		}
		if (defined($ident) and $ident ne "") {
			$data{$type}{$ident}{$name}{$key} = $data;
		} else {
			$data{$name}{$key} = $data
		}
	}
}

# Callback for end tag. E.g: </stat>
sub xml_end_elem {
	my $element = $_[1];
	if ($element ne "stat") {
		return;
	}

	xml_commit_state();
	xml_reset_state();
}

# Callback for opening tag. E.g: <stat>
sub xml_start_elem {
	$state{'field'} = $_[1];
	if ($state{'field'} eq "stat") {
		$state{'stat'} = 1;
	}
}

################################
# Internal API                 #
################################


# Populate %data, includes both values and descriptions and more.
# Currently driven by XML, but that could change.
sub populate_stats
{
	my $arg = "-x";
	my $parser = new XML::Parser(Handlers => {Start => \&xml_start_elem,
						End => \&xml_end_elem,
						Char => \&xml_characters} );

	if ($varnishname) {
		$arg .= " -n $varnishname";
	}
	open (XMLDATA, "$varnishstatexec $arg|") or die "meh";
	$parser->parse(*XMLDATA, ProtocolEncoding => 'ISO-8859-1');
	close(XMLDATA);
}

# Prints the fields in the list in $_[2] (e.g: 'value'/'description') for
# each identity of the varnish counter/family combination as defined by
# the $_[0]-counter on the aspect definition. Err, that's jibberish, so
# an example:
#
# e.g: dynamic_print('SMA_1','',('value'))
# e.g: dynamic_print('SMA_2','.label',('ident','description'))
# SMA_1 is the counter-value. If it is a dynamic counter, it has a counter
# and family-member (e.g: counter: c_req, family: SMA) and print_dynamic
# will print c_req for each SMA-identity.
#
# Note that the variables to print is a list. This is to allow printing a
# single item with multiple fields. Typically for identity+description so
# you can distinguish between different data points.
#
# Returns true if it was a dynamic counter.
sub print_dynamic
{
	my $name = $_[0];
	shift;
	my $suffix = $_[0];
	shift;
	my @field = @_;
	if (!defined($ASPECTS{$self}{'values'}{$name}{'counter'})) {
		return 0;
	}
	if (!defined($ASPECTS{$self}{'values'}{$name}{'family'})) {
		return 0;
	}
	my $counter = $ASPECTS{$self}{'values'}{$name}{'counter'};
	my $type = $ASPECTS{$self}{'values'}{$name}{'family'};

	foreach my $key (keys %{$data{$type}}) {
		my $pname = normalize_name($type . "_" . $key . "_" . $counter);
		print $pname . $suffix . " ";
		my $i = 0;
		foreach my $f (@field) {
			if ($i != 0) {
				print " ";
			}
			$i += 1;
			print $data{$type}{$key}{$counter}{$f};
		}
		print "\n";
	}
	return 1;
}

# Read and verify the aspect ($self).
sub set_aspect
{
	$self = $0;
	$self =~ s/^.*\/varnish_//;
	if (!defined($ASPECTS{$self}) && @ARGV == 0) {
		usage "No such aspect";
	}
}

# Print 'yes' if it's reasonable to use this plugin, or 'no' with a
# human-readable error message. Always exit true, even if the response
# is 'no'.
sub autoconf
{
	if (!$has_xml_parser) {
		print "no (missing perl module XML::Parser)\n";
	} elsif (`sh -c 'command -v "$varnishstatexec"'` =~ m{^/}) {
		print "yes\n";
	} else {
		print "no ($varnishstatexec could not be found)\n";
	}
	exit 0;
}

# Suggest relevant aspects/values of $self.
# 'DEBUG'-graphs are excluded.
sub suggest
{
	foreach my $key (keys %ASPECTS) {
		if (defined($ASPECTS{$key}{'DEBUG'}) && $FULL_SUGGEST != 1) {
			next;
		}
		print "$key\n";
	}
}

# Walk through the relevant aspect and print all top-level configuration
# values and value-definitions.
sub get_config
{
	my $graph = $_[0];

	# Need to double-check since set_aspect only checks this if there
	# is no argument (suggest/autoconf doesn't require a valid aspect)
	if (!defined($ASPECTS{$graph})) {
		usage "No such aspect";
	}
	my %values = %{$ASPECTS{$graph}{'values'}};

	print "graph_category loadbalancer\n";
	foreach my $field (@graph_parameters) {
		print_if_exist(\%ASPECTS,$graph,$field,"graph_$field");
	}

	foreach my $value (keys %values) {
		# Just print the description/type if it's a dynamic
		# counter. It'll be silent if it isn't.
		if(print_dynamic($value,'.label',('description','type','ident'))) {
			print_dynamic($value,'.type',('flag'));
			next;
		}

		# Need either RPN definition or a varnishstat value.
		if (!defined($data{$value}{'value'}) &&
		    !defined($values{$value}{'rpn'})) {
			if ($DEBUG) {
				print "ERROR: $value not part of varnishstat.\n"
			}
			next;
		}

		if (!print_if_exist(\%values,$value,'label')) {
			print "$value.label $data{$value}{'description'}\n";
		}
		foreach my $field (@field_parameters) {
			print_if_exist(\%values,$value,$field);
		}
	}
}

# Handle arguments (config, autoconf, suggest)
# Populate stats for config is necessary, but we want to avoid it for
# autoconf as it would generate a nasty error.
sub check_args
{
	if (@ARGV && $ARGV[0] eq '') {
		shift @ARGV;
	}
	if (@ARGV == 1) {
		if ($ARGV[0] eq "config") {
			populate_stats;
			get_config($self);
			exit 0;
		} elsif ($ARGV[0] eq "autoconf") {
			autoconf($self);
			exit 0;
		} elsif ($ARGV[0] eq "suggest") {
			suggest;
			exit 0;
		}
		usage "Unknown argument";
	}
}

################################
# Execution starts here        #
################################

set_aspect();
check_args();
populate_stats();

# We only get here if we're supposed to.
# Walks through the relevant values and either prints the varnishstat, or
# if the 'rpn' variable is set, calls rpn() to execute ... the rpn.
#
# NOTE: Due to differences in varnish-versions, this checks if the value
# actually exist before using it.
foreach my $value (keys %{$ASPECTS{$self}{'values'}}) {
	if (defined($ASPECTS{$self}{'values'}{$value}{'rpn'})) {
		print "$value.value ";
		rpn($ASPECTS{$self}{'values'}{$value}{'rpn'});
	} else {
		if (print_dynamic($value,'.value',('value'))) {
			next;
		}

		if (!defined($data{$value}{'value'})) {
			if ($DEBUG) {
				print STDERR "Error: $value not part of "
					   . "varnishstat.\n";
			}
			next;
		}
		print "$value.value ";
		print "$data{$value}{'value'}\n";
	}
}