add Datadog Statsd metrics

Gemfile

@@ -12,6 +12,7 @@ gem "sinatra", "~> 4.2"
 
 group :development, :test do
   gem "database_cleaner", "~> 2.0"
+  gem "dogstatsd-ruby", "~> 5.7", ">= 5.7.1"
   gem "dotenv", "~> 3.0"
   gem "factory_bot", "~> 6.0"
   gem "foreman", "~> 0.0"

Gemfile.lock

@@ -46,6 +46,7 @@ GEM
     database_cleaner-core (2.0.1)
     diff-lcs (1.5.1)
     docile (1.4.0)
+    dogstatsd-ruby (5.7.1)
     dotenv (3.1.2)
     drb (2.2.3)
     factory_bot (6.4.6)
@@ -169,6 +170,7 @@ PLATFORMS
 DEPENDENCIES
   coveralls_reborn
   database_cleaner (~> 2.0)
+  dogstatsd-ruby (~> 5.7, >= 5.7.1)
   dotenv (~> 3.0)
   factory_bot (~> 6.0)
   foreman (~> 0.0)

bin/outboxer_datadog_metrics

@@ -0,0 +1,60 @@
+#!/usr/bin/env ruby
+
+require "bundler/setup"
+
+begin
+  require "datadog/statsd"
+rescue LoadError
+  abort <<~MSG
+    dogstatsd-ruby is not installed.
+
+    Add it to your Gemfile:
+
+      gem "dogstatsd-ruby"
+
+    Then run bundle install.
+  MSG
+end
+
+require "outboxer"
+
+environment = ENV["RAILS_ENV"] || "development"
+db_config = Outboxer::Database.config(environment: environment, pool: 1)
+Outboxer::Database.connect(config: db_config)
+
+running = true
+
+["TERM", "INT"].each do |sig|
+  Signal.trap(sig) { running = false }
+end
+
+dogstatsd = Datadog::Statsd.new(
+  "127.0.0.1", 8125,
+  tags: ["env:#{environment}", "service:outboxer", "version:#{Outboxer::VERSION}"]
+)
+
+sleep_interval = 60
+tick_interval = 1
+
+logger = Outboxer::Logger.new($stdout, level: 1)
+logger.info "Sending outboxer.messages.* statsd metrics to datadog..."
+
+while running
+  Outboxer::Message.metrics_by_status.each do |status, metrics|
+    dogstatsd.gauge("outboxer.messages.count", metrics[:count], tags: ["status:#{status}"])
+
+    if metrics[:latency]
+      dogstatsd.gauge("outboxer.messages.latency", metrics[:latency], tags: ["status:#{status}"])
+    end
+  end
+
+  slept = 0
+
+  while running && slept < sleep_interval
+    sleep tick_interval
+
+    slept += tick_interval
+  end
+end
+
+logger.info "Shutting down"

generators/datadog_metrics_generator.rb

@@ -0,0 +1,30 @@
+module Outboxer
+  class InstallDatadogMetricsGenerator < Rails::Generators::Base
+    source_root File.expand_path("../", __dir__)
+
+    def copy_bin_file
+      template "bin/outboxer_datadog_metrics", "bin/outboxer_datadog_metrics"
+      run "chmod +x bin/outboxer_datadog_metrics"
+    end
+
+    def print_instructions
+      say <<~MSG
+
+        To complete setup:
+
+          1. Add to Gemfile:
+               gem "dogstatsd-ruby"
+
+          2. Run:
+               bundle install
+
+          3. Start:
+               bin/outboxer_datadog_metrics
+
+      MSG
+    end
+  end
+end
+
+# bundle exec rails g outboxer:install_datadog_metrics
+# bin/outboxer_datadog_metrics

generators/install_generator.rb

@@ -48,3 +48,5 @@ def copy_bin_file
     end
   end
 end
+
+# bundle exec rails g outboxer:install