Use the last number found.
+=item B<GaugePersist>
+
+Use the last number found. The number is not reset at the end of an interval.
+It is continously reported until another number is matched. This is intended
+for cases in which only state changes are reported, for example a thermometer
+that only reports the temperature when it changes.
+
=item B<CounterSet>
=item B<DeriveSet>
=item B<BlockDevice> I<name:dev>
-=item B<lockDeviceFormat> B<source>|B<dev>
-
-=item B<BlockDeviceFormatBasename> B<false>|B<true>
-
=item B<InterfaceDevice> I<name:dev>
=item B<IgnoreSelected> B<true>|B<false>
Ignore all I<hdb> devices on any domain, but other block devices (eg. I<hda>)
will be collected.
-If I<BlockDeviceFormat> is set to B<dev>, then the device names will be the ones
-in the I<target> node for the device in the XML definition of the domain. The
-default is B<dev>. This is the behavior before adding the option.
-
-If I<BlockDeviceFormat> is set to B<source>, then the device names will be the ones
-in the I<source> node for the device in the XML definition of the domain.
-
-Example:
-
-If the domain XML have the following device defined:
-
- <disk type='block' device='disk'>
- <driver name='qemu' type='raw' cache='none' io='native' discard='unmap'/>
- <source dev='/var/lib/libvirt/images/image1.qcow2'/>
- <target dev='sda' bus='scsi'/>
- <boot order='2'/>
- <address type='drive' controller='0' bus='0' target='0' unit='0'/>
- </disk>
-
-setting
+=item B<BlockDeviceFormat> B<target>|B<source>
- BlockDeviceFormat dev
+If I<BlockDeviceFormat> is set to B<target>, the default, then the device name
+seen by the guest will be used for reporting metrics.
+This corresponds to the C<E<lt>targetE<gt>> node in the XML definition of the
+domain.
-will name the device in the graph as sda
+If I<BlockDeviceFormat> is set to B<source>, then metrics will be reported
+using the path of the source, e.g. an image file.
+This corresponds to the C<E<lt>sourceE<gt>> node in the XML definition of the
+domain.
-setting
-
- BlockDeviceFormat source
+B<Example:>
-will name the device in the graph as var_lib_libvirt_images_image1.qcow2
+If the domain XML have the following device defined:
-These names will also be part of the RRD filename.
+ <disk type='block' device='disk'>
+ <driver name='qemu' type='raw' cache='none' io='native' discard='unmap'/>
+ <source dev='/var/lib/libvirt/images/image1.qcow2'/>
+ <target dev='sda' bus='scsi'/>
+ <boot order='2'/>
+ <address type='drive' controller='0' bus='0' target='0' unit='0'/>
+ </disk>
-I<BlockDeviceFormatBasename> - this option is honored if and only if
-option I<BlockDeviceFormat> is set to B<source>. If set to B<true> then
-only the last part of the path will be used for device name and naming the
-RRD file.
+Setting C<BlockDeviceFormat target> will cause the I<type instance> to be set
+to C<sda>.
+Setting C<BlockDeviceFormat source> will cause the I<type instance> to be set
+to C<var_lib_libvirt_images_image1.qcow2>.
-Example:
+=item B<BlockDeviceFormatBasename> B<false>|B<true>
-if the device path (source tag) is: /var/lib/libvirt/images/image1.qcow2
+The B<BlockDeviceFormatBasename> controls whether the full path or the
+L<basename(1)> of the source is being used as the I<type instance> when
+B<BlockDeviceFormat> is set to B<source>. Defaults to B<false>.
-setting:
- BlockDeviceFormatBasename true
+B<Example:>
-will set the device name to: image1.qcow2
+Assume the device path (source tag) is C</var/lib/libvirt/images/image1.qcow2>.
+Setting C<BlockDeviceFormatBasename false> will cause the I<type instance> to
+be set to C<var_lib_libvirt_images_image1.qcow2>.
+Setting C<BlockDeviceFormatBasename true> will cause the I<type instance> to be
+set to C<image1.qcow2>.
=item B<HostnameFormat> B<name|uuid|hostname|...>
=back
+=head2 Plugin C<write_prometheus>
+
+The I<write_prometheus plugin> implements a tiny webserver that can be scraped
+using I<Prometheus>.
+
+B<Options:>
+
+=over 4
+
+=item B<Port> I<Port>
+
+Port the embedded webserver should listen on. Defaults to B<9103>.
+
+=item B<StalenessDelta> I<Seconds>
+
+Time in seconds after which I<Prometheus> considers a metric "stale" if it
+hasn't seen any update for it. This value must match the setting in Prometheus.
+It defaults to B<300> seconds (5 minutes), same as Prometheus.
+
+B<Background:>
+
+I<Prometheus> has a global setting, C<StalenessDelta>, which controls after
+which time a metric without updates is considered "stale". This setting
+effectively puts an upper limit on the interval in which metrics are reported.
+
+When the I<write_prometheus plugin> encounters a metric with an interval
+exceeding this limit, it will inform you, the user, and provide the metric to
+I<Prometheus> B<without> a timestamp. That causes I<Prometheus> to consider the
+metric "fresh" each time it is scraped, with the time of the scrape being
+considered the time of the update. The result is that there appear more
+datapoints in I<Prometheus> than were actually created, but at least the metric
+doesn't disappear periodically.
+
+=back
+
=head2 Plugin C<write_http>
This output plugin submits values to an HTTP server using POST requests and
projects / collectd.git / blobdiff