monitoring: add textfile reporter to write Graphite-style metrics into file

.rubocop.yml

@@ -37,6 +37,9 @@ Metrics/PerceivedComplexity:
 Naming/UncommunicativeMethodParamName:
   Enabled: false
 
+Naming/MemoizedInstanceVariableName:
+  Enabled: false
+
 Style/ConditionalAssignment:
   Enabled: false
 
@@ -61,5 +64,8 @@ Style/InverseMethods:
 Style/NegatedIf:
   Enabled: false
 
+Style/RescueModifier:
+  Enabled: false
+
 Style/SymbolArray:
   Enabled: false

CHANGELOG.md

@@ -11,6 +11,7 @@ IMPROVEMENTS:
 - Add Ruby 2.5 support
 - Add experimental [OpenTracing](http://opentracing.io/) support with [CNCF Jaeger](https://github.com/jaegertracing/jaeger)
 - Support host offlining by deleting the associated DNS records
+- Add textfile reporter to write Graphite-style metrics (also compatible with [Prometheus](https://prometheus.io/)) into a file
 
 ## 1.6.1 (October 31, 2017)
 

README.md

@@ -135,7 +135,7 @@ The [Debian 6 init.d script](init.d/debian-6-dyndnsd) assumes that dyndnsd.rb is
 
 ### Monitoring
 
-For monitoring dyndnsd.rb uses the [metriks](https://github.com/eric/metriks) framework and exposes several metrics like the number of unauthenticated requests, requests that did (not) update a hostname, etc. By default the most important metrics are shown in the [proctitle](https://github.com/eric/metriks#proc-title-reporter) but you can also configure a [Graphite](https://graphiteapp.org/) backend for central monitoring.
+For monitoring dyndnsd.rb uses the [metriks](https://github.com/eric/metriks) framework and exposes several metrics like the number of unauthenticated requests, requests that did (not) update a hostname, etc. By default the most important metrics are shown in the [proctitle](https://github.com/eric/metriks#proc-title-reporter) but you can also configure a [Graphite](https://graphiteapp.org/) backend for central monitoring or the [textfile_reporter](https://github.com/prometheus/node_exporter/#textfile-collector) which outputs Graphite-style metrics that are also compatible with Prometheus to a file.
 
 ```yaml
 host: "0.0.0.0"
@@ -147,6 +147,10 @@ graphite:
   host: localhost # defaults for host and port of a carbon server
   port: 2003
   prefix: "my.graphite.metrics.naming.structure.dyndnsd"
+# OR configure the textfile reporter instead of Graphite/proctitle
+textfile:
+  file: /path/to/file.prom
+  prefix: "my.graphite.metrics.naming.structure.dyndnsd"
 # configure the updater, here we use command_with_bind_zone, params are updater-specific
 updater:
   name: "command_with_bind_zone"

lib/dyndnsd.rb

@@ -18,6 +18,7 @@ require 'dyndnsd/responder/dyndns_style'
 require 'dyndnsd/responder/rest_style'
 require 'dyndnsd/database'
 require 'dyndnsd/helper'
+require 'dyndnsd/textfile_reporter'
 require 'dyndnsd/version'
 
 module Dyndnsd
@@ -235,6 +236,12 @@ module Dyndnsd
         options[:prefix] = config['graphite']['prefix'] if config['graphite']['prefix']
         reporter = Metriks::Reporter::Graphite.new(host, port, options)
         reporter.start
+      elsif config['textfile']
+        file = config['textfile']['file'] || '/tmp/dyndnsd-metrics.prom'
+        options = {}
+        options[:prefix] = config['textfile']['prefix'] if config['textfile']['prefix']
+        reporter = Dyndnsd::TextfileReporter.new(file, options)
+        reporter.start
       else
         reporter = Metriks::Reporter::ProcTitle.new
         reporter.add 'good', 'sec' do

lib/dyndnsd/textfile_reporter.rb

@@ -0,0 +1,110 @@
+
+# Adapted from https://github.com/eric/metriks-graphite/blob/master/lib/metriks/reporter/graphite.rb
+
+require 'metriks'
+
+module Dyndnsd
+  class TextfileReporter
+    attr_reader :file
+
+    def initialize(file, options = {})
+      @file = file
+
+      @prefix = options[:prefix]
+
+      @registry  = options[:registry] || Metriks::Registry.default
+      @interval  = options[:interval] || 60
+      @on_error  = options[:on_error] || proc { |ex| }
+    end
+
+    def start
+      @thread ||= Thread.new do
+        loop do
+          sleep @interval
+
+          Thread.new do
+            begin
+              write
+            rescue StandardError => e
+              @on_error[e] rescue nil
+            end
+          end
+        end
+      end
+    end
+
+    def stop
+      @thread&.kill
+      @thread = nil
+    end
+
+    def restart
+      stop
+      start
+    end
+
+    def write
+      File.open(@file, 'w') do |f|
+        @registry.each do |name, metric|
+          case metric
+          when Metriks::Meter
+            write_metric f, name, metric, [
+              :count, :one_minute_rate, :five_minute_rate,
+              :fifteen_minute_rate, :mean_rate
+            ]
+          when Metriks::Counter
+            write_metric f, name, metric, [
+              :count
+            ]
+          when Metriks::UtilizationTimer
+            write_metric f, name, metric, [
+              :count, :one_minute_rate, :five_minute_rate,
+              :fifteen_minute_rate, :mean_rate,
+              :min, :max, :mean, :stddev,
+              :one_minute_utilization, :five_minute_utilization,
+              :fifteen_minute_utilization, :mean_utilization
+            ], [
+              :median, :get_95th_percentile
+            ]
+          when Metriks::Timer
+            write_metric f, name, metric, [
+              :count, :one_minute_rate, :five_minute_rate,
+              :fifteen_minute_rate, :mean_rate,
+              :min, :max, :mean, :stddev
+            ], [
+              :median, :get_95th_percentile
+            ]
+          when Metriks::Histogram
+            write_metric f, name, metric, [
+              :count, :min, :max, :mean, :stddev
+            ], [
+              :median, :get_95th_percentile
+            ]
+          end
+        end
+      end
+    end
+
+    def write_metric(file, base_name, metric, keys, snapshot_keys = [])
+      time = Time.now.to_i
+
+      base_name = base_name.to_s.gsub(/ +/, '_')
+      base_name = "#{@prefix}.#{base_name}" if @prefix
+
+      keys.flatten.each do |key|
+        name = key.to_s.gsub(/^get_/, '')
+        value = metric.send(key)
+        file.write("#{base_name}.#{name} #{value} #{time}\n")
+      end
+
+      unless snapshot_keys.empty?
+        snapshot = metric.snapshot
+        snapshot_keys.flatten.each do |key|
+          name = key.to_s.gsub(/^get_/, '')
+          value = snapshot.send(key)
+          file.write("#{base_name}.#{name} #{value} #{time}\n")
+        end
+      end
+    end
+  end
+end