This is a Lua plugin for the Nginx web server that automatically collects and submits several important Nginx metrics to [Graphite](https://graphiteapp.org/) suitable for visualisation with e.g. [Grafana](http://grafana.org/).
In constrast to commercial and proprietary solutions such as [Luameter](https://luameter.com/) or [NGINX Plus](https://www.nginx.com/products/) with it's [ngx_http_status_module](http://nginx.org/en/docs/http/ngx_http_status_module.html), this plugin is open source software while featuring more and additional metrics compared to those available via the open source [ngx_http_stub_status_module](http://nginx.org/en/docs/http/ngx_http_stub_status_module.html). (Yea, [other web servers](https://redmine.lighttpd.net/projects/1/wiki/Docs_ModStatus) deliver more information by default...)
This plugin takes inspiration from other Nginx metric libraries like [nginx-lua-prometheus](https://github.com/knyar/nginx-lua-prometheus) but differs fundamentally in the metrics submission handling by. In certain intervals it automatically pushes metrics to the configured Graphite (i.e. Carbon) host using pure Lua code instead of exposing them via a separate web page for polling.
The metrics collection happens on every request for which the user configures a suitable `log_by_lua` direcitve and towards server-wide global counters (finer granularity might be added later). The counters are realized using a single shared dictionary across all Nginx worker threads which has constant memory usage (128 KiB currently, may be reduced further).
Collected metrics in this prototype implementation:
Intermittent network errors while communicating with Graphite might leed to permanent loss of metric information. The communication happens in clear text and thus needs a secure separate network or other means.
