NAME

       "Net::Prometheus" - export monitoring metrics for prometheus

SYNOPSIS

          use Net::Prometheus;

          my $client = Net::Prometheus->new;

          my $counter = $client->new_counter(
             name => "requests",
             help => "Number of received requests",
          );

          sub handle_request
          {
             $counter->inc;
             ...
          }

          use Plack::Builder;

          builder {
             mount "/metrics" => $client->psgi_app;
             ...
          }

DESCRIPTION

       This module provides the ability for a program to collect monitoring metrics and export them to the
       prometheus.io monitoring server.

       As "prometheus" will expect to collect the metrics by making an HTTP request, facilities are provided to
       yield a PSGI application that the containing program can embed in its own structure to provide the
       results, or the application can generate a plain-text result directly and serve them by its own means.

CONSTRUCTOR

   new
          $prometheus = Net::Prometheus->new;

       Returns a new "Net::Prometheus" instance.

       Takes the following named arguments:

       disable_process_collector => BOOL
           If present and true, this instance will not load the default process collector from
           Net::Prometheus::ProcessCollector. If absent or false, such a collector will be loaded by default.
           This is usually what you want.

METHODS

   register
          $collector = $prometheus->register( $collector )

       Registers a new collector to be collected from by the "render" method. The collector instance itself is
       returned, for convenience.

   unregister
          $prometheus->unregister( $collector )

       Removes a previously-registered collector.

   new_gauge
          $gauge = $prometheus->new_gauge( %args )

       Constructs a new Net::Prometheus::Gauge using the arguments given and registers it with the exporter. The
       newly-constructed gauge is returned.

   new_counter
          $counter = $prometheus->new_counter( %args )

       Constructs a new Net::Prometheus::Counter using the arguments given and registers it with the exporter.
       The newly-constructed counter is returned.

   new_summary
          $summary = $prometheus->new_summary( %args )

       Constructs a new Net::Prometheus::Summary using the arguments given and registers it with the exporter.
       The newly-constructed summary is returned.

   new_histogram
          $histogram = $prometheus->new_histogram( %args )

       Constructs a new Net::Prometheus::Histogram using the arguments given and registers it with the exporter.
       The newly-constructed histogram is returned.

   new_metricgroup
          $group = $prometheus->new_metricgroup( %args )

       Returns a new Metric Group instance as a convenience for registering multiple metrics using the same
       "namespace" and "subsystem" arguments. Takes the following named arguments:

       namespace => STR
       subsystem => STR
           String values to pass by default into new metrics the group will construct.

       Once constructed, the group acts as a proxy to the other "new_*" methods, passing in these values as
       overrides.

          $gauge = $group->new_gauge( ... )
          $counter = $group->new_counter( ... )
          $summary = $group->new_summary( ... )
          $histogram = $group->new_histogram( ... )

   collect
          @metricsamples = $prometheus->collect

       Returns a list of "MetricSamples" in Net::Prometheus::Types obtained from all of the currently-registered
       collectors.

   render
          $str = $prometheus->render

       Returns a string in the Prometheus text exposition format containing the current values of all the
       registered metrics.

   psgi_app
          $app = $prometheus->psgi_app

       Returns a new PSGI application as a "CODE" reference. This application will render the metrics in the
       Prometheus text exposition format, suitable for scraping by the Prometheus collector.

       This application will respond to any "GET" request, and reject requests for any other method.

COLLECTORS

       The toplevel "Net::Prometheus" object stores a list of "collector" instances, which are used to generate
       the values that will be made visible via the "render" method. A collector can be any object instance that
       has a method called "collect", which when invoked is passed no arguments and expected to return a list of
       "MetricSamples" in Net::Prometheus::Types structures.

          @metricsamples = $collector->collect

       The Net::Prometheus::Metric class is already a valid collector (and hence, so too are the individual
       metric type subclasses). This interface allows the creation of new custom collector objects, that more
       directly collect information to be exported.

TODO

       •       Perl-specific variable collector - arena stats?

       •       Split Registry out from toplevel instance.

       •       Write some actual example programs.

AUTHOR

       Paul Evans <leonerd@leonerd.org.uk>