feature: Send collected data to graphite server (#6201)

* Initial support for graphite

* Enable graphite include

* fixed typos.

* Fixed port naming to graphite metric names

* Added documentation for Graphite

* added documentation for graphite

* fixed style

* replace / with _ in interface names for graphite

* sets default graphite port

* adds rrd-name tags to the metric, otherwise metrics get lost

* add suggested storage schema for graphite

* add whitespace

* Updated to show some output

* bad english

doc/Extensions/Graphite.md

@@ -0,0 +1,32 @@
+source: Extensions/Graphite.md
+# Enabling support for Graphite.
+
+This module sends all metrics to a remote graphite service. You need something like Grafana for graphing.
+
+### What you don't get
+ - Pretty graphs, this is why at present you need Grafana. You need to build your own graphs within Grafana.
+
+RRD will continue to function as normal so LibreNMS itself should continue to function as normal.
+
+### Configuration
+```php
+$config['graphite']['enable'] = true;
+$config['graphite']['host'] = 'your.graphite.server';
+$config['graphite']['port'] = 2003; // this defaults to 2003 and is usually not needed
+$config['graphite']['prefix'] = 'your.metric.prefix';
+```
+
+Your metric path can be prefixed if required, otherwise the metric path for Graphite will be in the form of
+`hostname.measurement.fieldname`, interfaces will be stored as `hostname.ports.ifName.fieldname`.
+
+The same data then stored within rrd will be sent to Graphite and recorded. You can then create graphs within Grafana
+to display the information you need.
+
+### Graphite Configuration
+As LibreNMS updates its metrics every 5 minutes, the following addition to your storage-schemas.conf is suggested.
+
+```
+[network]
+pattern = your\.metric\.prefix\..*
+retentions = 5m:30d,15m:90d,1h:1y
+```