class GitLab::Exporter::PrometheusMetrics

Prometheus metrics container

Provides a simple API to `add` metrics and then turn them `to_s` which will just dump all the metrics in prometheus format

The add method also can take any arbitrary amount of labels in a `key: value` format.

Public Class Methods

clear_descriptions() click to toggle source
# File lib/gitlab_exporter/prometheus.rb, line 28
def clear_descriptions
  @metric_descriptions = {}
end
describe(name, description) click to toggle source
# File lib/gitlab_exporter/prometheus.rb, line 19
def describe(name, description)
  @metric_descriptions ||= {}
  @metric_descriptions[name] = description
end
description(name) click to toggle source
# File lib/gitlab_exporter/prometheus.rb, line 24
def description(name)
  @metric_descriptions && @metric_descriptions[name]
end
new(include_timestamp: true) click to toggle source
# File lib/gitlab_exporter/prometheus.rb, line 12
def initialize(include_timestamp: true)
  @metrics = Hash.new { |h, k| h[k] = [] }
  @quantiles = Hash.new { |h, k| h[k] = [] }
  @include_timestamp = include_timestamp
end

Public Instance Methods

add(name, value, quantile = false, **labels) click to toggle source
# File lib/gitlab_exporter/prometheus.rb, line 33
def add(name, value, quantile = false, **labels)
  fail "value '#{value}' must be a number" unless value.is_a?(Numeric)

  if quantile
    @quantiles[{ name: name, labels: labels }] << value
  else
    @metrics[name] << { value: value, labels: labels, timestamp: (Time.now.to_f * 1000).to_i }
  end

  self
end
to_s() click to toggle source
# File lib/gitlab_exporter/prometheus.rb, line 45
def to_s
  add_quantiles_to_metrics

  buffer = ""
  @metrics.each do |name, measurements|
    buffer << "# HELP #{name} #{self.class.description(name)}\n" if self.class.description(name)

    measurements.each do |measurement|
      buffer << name.to_s
      labels = (measurement[:labels] || {}).map { |label, value| "#{label}=\"#{value}\"" }.join(",")
      buffer << "{#{labels}}" unless labels.empty?
      buffer << " #{measurement[:value]}"
      buffer << " #{measurement[:timestamp]}" if @include_timestamp
      buffer << "\n"
    end
  end
  buffer
end

Private Instance Methods

add_quantiles_to_metrics() click to toggle source
# File lib/gitlab_exporter/prometheus.rb, line 66
def add_quantiles_to_metrics
  @quantiles.each do |data, measurements|
    estimator = Quantile::Estimator.new

    measurements.each do |value|
      estimator.observe(value)
    end

    estimator.invariants.each do |invariant|
      data[:labels][:quantile] = "#{(invariant.quantile * 100).to_i}th"

      add(data[:name], estimator.query(invariant.quantile), **data[:labels])
    end
  end
end