Module: GovukPrometheusExporter

Defined in:
lib/govuk_app_config/govuk_prometheus_exporter.rb

Defined Under Namespace

Classes: RailsMiddleware, SinatraMiddleware

Class Method Summary collapse

Class Method Details

.configure(collectors: [], default_aggregation: PrometheusExporter::Metric::Histogram) ⇒ Object 



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# File 'lib/govuk_app_config/govuk_prometheus_exporter.rb', line 56

def self.configure(collectors: [], default_aggregation: PrometheusExporter::Metric::Histogram)
  return unless should_configure

  # PrometheusExporter::Metric::Histogram.DEFAULT_BUCKETS tops out at 10 but
  # we have a few controller actions which are slower than this, so we add a
  # few extra buckets for slower requests
  PrometheusExporter::Metric::Histogram.default_buckets = [0.005, 0.01, 0.025, 0.05, 0.1, 0.25, 0.5, 1, 2.5, 5, 10, 15, 25, 50].freeze
  PrometheusExporter::Metric::Base.default_aggregation = default_aggregation

  if defined?(Sidekiq)
    Sidekiq.configure_server do |config|
      require "sidekiq/api"
      require "prometheus_exporter/instrumentation"
      config.server_middleware do |chain|
        chain.add PrometheusExporter::Instrumentation::Sidekiq
      end
      config.death_handlers << PrometheusExporter::Instrumentation::Sidekiq.death_handler
      config.on :startup do
        PrometheusExporter::Instrumentation::Process.start(type: "sidekiq")
        PrometheusExporter::Instrumentation::SidekiqProcess.start
        PrometheusExporter::Instrumentation::SidekiqQueue.start
        PrometheusExporter::Instrumentation::SidekiqStats.start
      end
    end
  end

  begin
    server = PrometheusExporter::Server::WebServer.new bind: "0.0.0.0", port: 9394

    collectors.each { |collector| server.collector.register_collector(collector.new) }

    server.start

    if defined?(Rails)
      Rails.application.middleware.unshift RailsMiddleware, instrument: :prepend
    end

    if defined?(Sinatra)
      Sinatra.use SinatraMiddleware
    end
  rescue Errno::EADDRINUSE
    warn "Could not start Prometheus metrics server as address already in use."
  end
end

.should_configure ⇒ Object 



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# File 'lib/govuk_app_config/govuk_prometheus_exporter.rb', line 44

def self.should_configure
  # Allow us to force the Prometheus Exporter for persistent Rake tasks...
  if ENV["GOVUK_PROMETHEUS_EXPORTER"] == "force"
    true
  elsif File.basename($PROGRAM_NAME) == "rake" ||
      defined?(Rails) && (Rails.const_defined?("Console") || Rails.env == "test")
    false
  else
    ENV["GOVUK_PROMETHEUS_EXPORTER"] == "true"
  end
end