Class: GitLab::Exporter::PrometheusMetrics

Inherits:
Object
  • Object
show all
Defined in:
lib/gitlab_exporter/prometheus.rb

Overview

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.

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(include_timestamp: true) ⇒ PrometheusMetrics

Returns a new instance of PrometheusMetrics.



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# 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

Class Method Details

.clear_descriptions ⇒ Object 



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# File 'lib/gitlab_exporter/prometheus.rb', line 28

def clear_descriptions
  @metric_descriptions = {}
end

.describe(name, description) ⇒ Object 



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# File 'lib/gitlab_exporter/prometheus.rb', line 19

def describe(name, description)
  @metric_descriptions ||= {}
  @metric_descriptions[name] = description
end

.description(name) ⇒ Object 



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# File 'lib/gitlab_exporter/prometheus.rb', line 24

def description(name)
  @metric_descriptions && @metric_descriptions[name]
end

Instance Method Details

#add(name, value, quantile = false, **labels) ⇒ Object 



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# 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 ⇒ Object 



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# 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