Module: Rubino::Metrics::Renderer

Defined in:
lib/rubino/metrics.rb

Overview

Serializes metrics to Prometheus text exposition format:

# HELP name help text
# TYPE name counter|histogram
name{label="value",...} value

Label values are escaped for ‘“`, ``, and newline.

Class Method Summary collapse

Class Method Details

.call(metrics) ⇒ Object 



142
143
144
 
# File 'lib/rubino/metrics.rb', line 142

def self.call(metrics)
  metrics.flat_map { |m| render_metric(m) }.join("\n") + "\n"
end

.escape(value) ⇒ Object 



170
171
172
 
# File 'lib/rubino/metrics.rb', line 170

def self.escape(value)
  value.to_s.gsub("\\", "\\\\").gsub('"', '\\"').gsub("\n", '\n')
end

.format_labels(labels) ⇒ Object 



163
164
165
166
167
168
 
# File 'lib/rubino/metrics.rb', line 163

def self.format_labels(labels)
  return "" if labels.empty?

  pairs = labels.map { |k, v| %(#{k}="#{escape(v)}") }.join(",")
  "{#{pairs}}"
end

.render_metric(metric) ⇒ Object 



146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
 
# File 'lib/rubino/metrics.rb', line 146

def self.render_metric(metric)
  lines = ["# HELP #{metric.name} #{metric.help}", "# TYPE #{metric.name} #{metric.type}"]
  case metric.type
  when :counter
    metric.each { |labels, value| lines << "#{metric.name}#{format_labels(labels)} #{value}" }
  when :histogram
    metric.each do |labels, data|
      data[:counts].each do |bucket, count|
        lines << "#{metric.name}_bucket#{format_labels(labels.merge(le: bucket.to_s))} #{count}"
      end
      lines << "#{metric.name}_sum#{format_labels(labels)} #{data[:sum]}"
      lines << "#{metric.name}_count#{format_labels(labels)} #{data[:count]}"
    end
  end
  lines
end