Module: Emrb

Defined in:
lib/emrb.rb,
lib/emrb/server.rb,
lib/emrb/version.rb,
lib/emrb/instruments/state.rb,
lib/emrb/instruments/exporters.rb,
lib/emrb/instruments/instruments.rb

Overview

Emrb provides a facility for instrumenting applications with prometheus metrics. All instruments can be used the same way as in prometheus-client, and are registered within the same registry. Both Prometheus::Middleware::Collector and Prometheus::Middleware::Exporter can be accessed using Emrb::Collector and Emrb::Exporter.

Defined Under Namespace

Modules: Instruments

Constant Summary collapse

VERSION = 
"0.1.5"
Exporter =

Rack middleware that provides a sample implementation of a Prometheus HTTP exposition endpoint.

By default it will export the state of the global registry and expose it under ‘/metrics`. Use the `:registry` and `:path` options to change the defaults. Original source: github.com/prometheus/client_ruby/blob/main/lib/prometheus/middleware/exporter.rb

Prometheus::Middleware::Exporter
Collector =

Rack middleware that provides a sample implementation of a HTTP tracer.

By default metrics are registered on the global registry. Set the ‘:registry` option to use a custom registry.

By default metrics all have the prefix “http_server”. Set ‘:metrics_prefix` to something else if you like.

The request counter metric is broken down by code, method and path. The request duration metric is broken down by method and path. Original source: github.com/prometheus/client_ruby/blob/main/lib/prometheus/middleware/collector.rb

Prometheus::Middleware::Collector

Class Method Summary collapse

Class Method Details

.expose_metrics(port, address = "0.0.0.0") ⇒ Object

expose_metrics starts a simple sinatra server on a given port and address that exposes a single /metrics endpoint for scrapers to access. It is a courtesy utility for applications not exposing an HTTP server by default.

To use this method, the application calling it must bundle both sinatra and puma gems.

port - Port to expose the server address - Address to expose the server. Defaults to ‘0.0.0.0`.

Returns nothing.



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# File 'lib/emrb/server.rb', line 34

def self.expose_metrics(port, address = "0.0.0.0")
  return if @metrics_app

  metrics_app = Class.new(Sinatra::Base) do
    set :bind, address
    set :port, port
    use Emrb::Exporter
    use Rack::Deflater
  end

  @metrics_app = metrics_app.new
  puma_server = Puma::Server.new(metrics_app)
  puma_server.add_tcp_listener(address, port)
  @puma_server = puma_server
  @metrics_thr = Thread.new { puma_server.run }
end

.stop_exposing_metrics ⇒ Object

Stops the metrics server previously started by #expose_metrics.

Returns nothing.



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# File 'lib/emrb/server.rb', line 54

def self.stop_exposing_metrics
  return unless @metrics_app

  @puma_server.stop(true)
  @metrics_thr.join
end