3 collectd-exec - Documentation of collectd's C<exec plugin>
11 Exec "myuser:mygroup" "myprog"
12 Exec "otheruser" "/path/to/another/binary"
13 NotificationExec "user" "/usr/lib/collectd/exec/handle_notification"
14 NagiosExec "nagios:nagios" "/usr/lib/nagios/plugins/check_something"
19 The C<exec plugin> forks of an executable either to receive values, to dispatch
20 notifications to the outside world or to be able to use Nagios plugins.
22 If you want/need better performance or more functionality you should take a
23 long look at the C<perl plugin>, L<collectd-perl(5)>.
25 =head1 EXECUTABLE TYPES
27 There are currently three types of executables that can be executed by the
34 These programs are forked and values that it writes to C<STDOUT> are read back.
35 The executable is forked in a fashion similar to L<init>: It is forked once and
36 not again until it exits. If it exited, it will be forked again after at most
37 I<Interval> seconds. It is perfectly legal for the executable to run for a long
38 time and continuously write values to C<STDOUT>.
40 See L<EXEC DATA FORMAT> below for a description of the output format expected
43 B<Warning:> If the executable only writes one value and then exits I will be
44 executed every I<Interval> seconds. If I<Interval> is short (the default is 10
45 seconds) this may result in serious system load.
47 =item C<NotificationExec>
49 The program is forked once for each notification that is handled by the daemon.
50 The notification is passed to the program on C<STDIN> in a fashion similar to
51 HTTP-headers. In contrast to programs specified with C<Exec> the execution of
52 this program is not serialized, so that several instances of this program may
53 run at once if multiple notifications are received.
55 See L<NOTIFICATION DATA FORMAT> below for a description of the data passed to
60 The executable is treated as a Nagios plugin. That means that the first line
61 printed to C<STDOUT> by this program is used as the text of a notification and
62 the severity of the notification depends on the exit status of the executable
65 For information on how to write Nagios plugins please refer to the Nagios
66 documentation. If a plugin works with Nagios but not with collectd please
67 complain on the collectd mailing list instead.
71 =head1 EXEC DATA FORMAT
73 The forked executable is expected to print values to C<STDOUT>. The expected
80 Each line beginning with a C<#> (hash mark) is ignored.
84 Other lines must consist of an I<Identifier>, an optional I<Option-List> and a
85 I<Value-List>, separated by a spaces. A description of these two parts follows:
87 An I<Identifier> is of the form
88 C<I<host>B</>I<plugin>B<->I<instance>B</>I<type>B<->I<instance>> with both
89 I<instance>-parts being optional. If they're omitted the hyphen must be
92 The I<OptionList> is an optional list of I<Options>, where each option if a
93 key-value-pair. A list of currently understood options can be found below, all
94 other options will be ignored.
96 I<Valuelist> is a colon-separated list of the time and the values, each either
97 an integer if the data-source is a counter, of a double if the data-source if
98 of type "gauge". You can submit an undefined gauge-value by using B<U>. When
99 submitting B<U> to a counter the behavior is undefined. The time is given as
100 epoch (i.E<nbsp>e. standard UNIX time).
102 You can mix options and values, but the order is important: Options only
103 effect following values, so specifying an option as last field is allowed, but
104 useless. Also, an option applies to B<all> following values, so you don't need
105 to re-set an option over and over again.
107 The currently defined B<Options> are:
111 =item B<interval=>I<seconds>
113 Gives the interval in which the data identified by I<Identifier> is being
118 Please note that this is the same format as used in the B<unixsock plugin>, see
119 L<collectd-unixsock(5)>. There's also a bit more information on identifiers in
120 case you're confused.
122 Since examples usually let one understand a lot better, here are some:
124 leeloo/cpu-0/cpu-idle N:2299366
125 alice/interface/if_octets-eth0 interval=10 1180647081:421465:479194
129 When collectd exits it sends a B<SIGTERM> to all still running
130 child-processes upon which they have to quit.
132 =head1 NOTIFICATION DATA FORMAT
134 The notification executables receive values rather than providing them. In
135 fact, after the program is started C<STDOUT> is connected to C</dev/null>.
137 The data is passed to the executables over C<STDIN> in a format very similar to
138 HTTP-headers: There is one line per field. Every line consists of a field name,
139 ended by a colon, and the associated value until end-of-line. The input is
140 ended by two newlines immediately following another.
142 The following is an example notification passed to a program:
146 Host: myhost.mydomain.org
147 Message: This is a test notification to demonstrate the format
150 The following header files are currently used. Please note, however, that you
151 should ignore unknown header files to be as forward-compatible as possible.
157 Severity of the notification. May either be B<FAILURE>, B<WARNING>, or B<OKAY>.
161 The time in epoch, i.E<nbsp>e. as seconds since 1970-01-01 00:00:00 UTC.
165 Name of the host concerned.
169 Message of the notification. This message should be made accessible to the
180 The user, the binary is executed as, may not have root privileges, i.E<nbsp>e.
181 must have an UID that is non-zero. This is for your own good.
190 L<collectd-unixsock(5)>,
191 L<fork(2)>, L<exec(3)>
195 Florian Forster E<lt>octo@verplant.orgE<gt>