# ...
<Plugin exec>
Exec "myuser:mygroup" "myprog"
- Exec "otheruser" "/path/to/another/binary"
+ Exec "otheruser" "/path/to/another/binary" "arg0" "arg1"
+ NotificationExec "user" "/usr/lib/collectd/exec/handle_notification"
+ NagiosExec "nagios:nagios" "/usr/lib/nagios/plugins/check_something"
</Plugin>
=head1 DESCRIPTION
-The C<exec plugin> forks of an executable and reads back values that it writes
-to C<STDOUT>. The executable is forked in a fashion similar to L<init>: It is
-forked once and not again until it exits. If it exited, it will be forked again
-after at most I<Interval> seconds. It is perfectly legal for the executable to
-run for a long time and continuously write values to C<STDOUT>.
+The C<exec plugin> forks of an executable either to receive values, to dispatch
+notifications to the outside world or to be able to use Nagios plugins. The
+syntax of the configuration is explained in L<collectd.conf(5)> but summarized
+in the above synopsis.
If you want/need better performance or more functionality you should take a
long look at the C<perl plugin>, L<collectd-perl(5)>.
-=head1 DATA FORMAT
+=head1 EXECUTABLE TYPES
+
+There are currently three types of executables that can be executed by the
+C<exec plugin>:
+
+=over 4
+
+=item C<Exec>
+
+These programs are forked and values that it writes to C<STDOUT> are read back.
+The executable is forked in a fashion similar to L<init>: It is forked once and
+not again until it exits. If it exited, it will be forked again after at most
+I<Interval> seconds. It is perfectly legal for the executable to run for a long
+time and continuously write values to C<STDOUT>.
+
+See L<EXEC DATA FORMAT> below for a description of the output format expected
+from these programs.
+
+B<Warning:> If the executable only writes one value and then exits I will be
+executed every I<Interval> seconds. If I<Interval> is short (the default is 10
+seconds) this may result in serious system load.
+
+=item C<NotificationExec>
+
+The program is forked once for each notification that is handled by the daemon.
+The notification is passed to the program on C<STDIN> in a fashion similar to
+HTTP-headers. In contrast to programs specified with C<Exec> the execution of
+this program is not serialized, so that several instances of this program may
+run at once if multiple notifications are received.
+
+See L<NOTIFICATION DATA FORMAT> below for a description of the data passed to
+these programs.
+
+=item C<NagiosExec>
+
+The executable is treated as a Nagios plugin. That means that the first line
+printed to C<STDOUT> by this program is used as the text of a notification and
+the severity of the notification depends on the exit status of the executable
+only.
+
+For information on how to write Nagios plugins please refer to the Nagios
+documentation. If a plugin works with Nagios but not with collectd please
+complain on the collectd mailing list instead.
+
+=back
+
+=head1 EXEC DATA FORMAT
The forked executable is expected to print values to C<STDOUT>. The expected
format is as follows:
=over 4
-=item
+=item Comments
Each line beginning with a C<#> (hash mark) is ignored.
-=item
+=item B<PUTVAL> I<Identifier> [I<OptionList>] I<Valuelist>
-Other lines must consist of an I<Identifier>, an optional I<Option-List> and a
-I<Value-List>, separated by a spaces. A description of these two parts follows:
+Submits one or more values (identified by I<Identifier>, see below) to the
+daemon which will dispatch it to all it's write-plugins.
An I<Identifier> is of the form
C<I<host>B</>I<plugin>B<->I<instance>B</>I<type>B<->I<instance>> with both
as the tuple (plugin, plugin instance, type instance) uniquely identifies the
plugin within collectd. I<type> identifies the type and number of values
(i.E<nbsp>e. data-set) passed to collectd. A large list of predefined
-data-sets is available in the B<types.db> file.
+data-sets is available in the B<types.db> file. See L<types.db(5)> for a
+description of the format of this file.
The I<OptionList> is an optional list of I<Options>, where each option if a
key-value-pair. A list of currently understood options can be found below, all
leeloo/cpu-0/cpu-idle N:2299366
alice/interface/if_octets-eth0 interval=10 1180647081:421465:479194
+Since this action was the only one supported with older versions of the C<exec
+plugin> all lines were treated as if they were prefixed with B<PUTVAL>. This is
+still the case to maintain backwards compatibility but deprecated.
+
+=item B<PUTNOTIF> [I<OptionList>] B<message=>I<Message>
+
+Submits a notification to the daemon which will then dispatch it to all plugins
+which have registered for receiving notifications.
+
+The B<PUTNOTIF> if followed by a list of options which further describe the
+notification. The B<message> option is special in that it will consume the rest
+of the line as its value. The B<message>, B<severity>, and B<time> options are
+mandatory.
+
+Valid options are:
+
+=over 4
+
+=item B<message=>I<Message> (B<REQUIRED>)
+
+Sets the message of the notification. This is the message that will be made
+accessible to the user, so it should contain some useful information. This
+option must be the last option because the rest of the line will be its value,
+even if there are spaces and equal-signs following it! This option is
+mandatory.
+
+=item B<severity=failure>|B<warning>|B<okay> (B<REQUIRED>)
+
+Sets the severity of the notification. This option is mandatory.
+
+=item B<time=>I<Time> (B<REQUIRED>)
+
+Sets the time of the notification. The time is given as "epoch", i.E<nbsp>e. as
+seconds since January 1st, 1970, 00:00:00. This option is mandatory.
+
+=item B<host=>I<Hostname>
+
+=item B<plugin=>I<Plugin>
+
+=item B<plugin_instance=>I<Plugin-Instance>
+
+=item B<type=>I<Type>
+
+=item B<type_instance=>I<Type-Instance>
+
+These "associative" options establish a relation between this notification and
+collected performance data. This connection is purely informal, i.E<nbsp>e. the
+daemon itself doesn't do anything with this information. However, websites or
+GUIs may use this information to place notifications near the affected graph or
+table. All the options are optional, but B<plugin_instance> without B<plugin>
+or B<type_instance> without B<type> doesn't make much sense and should be
+avoided.
+
+Please note that this is the same format as used in the B<unixsock plugin>, see
+L<collectd-unixsock(5)>.
+
=back
When collectd exits it sends a B<SIGTERM> to all still running
child-processes upon which they have to quit.
-=head1 CAVEATS
+=head1 NOTIFICATION DATA FORMAT
+
+The notification executables receive values rather than providing them. In
+fact, after the program is started C<STDOUT> is connected to C</dev/null>.
+
+The data is passed to the executables over C<STDIN> in a format very similar to
+HTTP-headers: There is one line per field. Every line consists of a field name,
+ended by a colon, and the associated value until end-of-line. The input is
+ended by two newlines immediately following another.
+
+The following is an example notification passed to a program:
+
+ Severity: FAILURE
+ Time: 1200928930
+ Host: myhost.mydomain.org
+ Message: This is a test notification to demonstrate the format
+ <newline>
+
+The following header files are currently used. Please note, however, that you
+should ignore unknown header files to be as forward-compatible as possible.
=over 4
-=item
+=item B<Severity>
+
+Severity of the notification. May either be B<FAILURE>, B<WARNING>, or B<OKAY>.
+
+=item B<Time>
+
+The time in epoch, i.E<nbsp>e. as seconds since 1970-01-01 00:00:00 UTC.
+
+=item B<Host>
+
+Name of the host concerned.
-If the executable only writes one value and then exits I will be executed every
-I<Interval> seconds. If I<Interval> is short (the default is 10 seconds) this
-may result in serious system load.
+=item B<Message>
+
+Message of the notification. This message should be made accessible to the
+user somehow.
+
+=back
+
+=head1 CAVEATS
+
+=over 4
=item
The user, the binary is executed as, may not have root privileges, i.E<nbsp>e.
-must have an UID that is non-zero.
+must have an UID that is non-zero. This is for your own good.
=back
projects / collectd.git / blobdiff