Update prometheus-client. Use my fork with the :most_recent aggregation.

Author: stefansundin

Gemfile

@@ -11,7 +11,7 @@ gem "addressable"
 gem "rack-ssl-enforcer"
 gem "clogger"
 gem "encrypted_strings"
-gem "prometheus-client", require: "prometheus/middleware/exporter"
+gem "prometheus-client", require: "prometheus/middleware/exporter", git: "https://github.com/stefansundin/prometheus-client.git", branch: "add-most_recent-aggregation"
 
 group :production do
  gem "airbrake", require: false

Gemfile.lock

@@ -1,3 +1,10 @@
+GIT
+ remote: https://github.com/stefansundin/prometheus-client.git
+ revision: 5256cdfb78d5bfec1b8fbb78dcc1a2eee6c8989f
+ branch: add-most_recent-aggregation
+ specs:
+ prometheus-client (1.0.0)
+
 GEM
  remote: https://rubygems.org/
  specs:
@@ -30,8 +37,6 @@ GEM
  nio4r (2.5.2)
  powder (0.4.0)
  thor (>= 0.11.5)
- prometheus-client (0.9.0)
- quantile (~> 0.2.1)
  pry (0.12.2)
  coderay (~> 1.1.0)
  method_source (~> 0.9.0)
@@ -41,7 +46,6 @@ GEM
  public_suffix (4.0.1)
  puma (4.3.1)
  nio4r (~> 2.0)
- quantile (0.2.1)
  rack (2.0.8)
  rack-protection (2.0.7)
  rack
@@ -78,7 +82,7 @@ DEPENDENCIES
  github-release-party
  newrelic_rpm
  powder
- prometheus-client
+ prometheus-client!
  pry-remote
  puma
  rack

app/github.rb

@@ -164,7 +164,7 @@ def self.graphql(query, variables, token=nil)
  }.to_json, headers)
  response = HTTPResponse.new(raw_response, uri.to_s)
  if response.json && response.json["data"] && response.json["data"]["rateLimit"] && response.json["data"]["rateLimit"]["remaining"]
- $metrics[:ratelimit_remaining].set({}, response.json["data"]["rateLimit"]["remaining"])
+ $metrics[:ratelimit_remaining].set(response.json["data"]["rateLimit"]["remaining"])
  end
  return response
  end

config/initializers/40-prometheus.rb

@@ -1,7 +1,21 @@
-# The app is currently run with multiple processes, which means that the /metrics endpoint is not consistent.. That's fine for now, at least with this one metric.
+# frozen_string_literal: true
+
+# Use DirectFileStore if we run multiple processes
+store_settings = {}
+if ENV["WEB_CONCURRENCY"]
+ require "prometheus/client/data_stores/direct_file_store"
+ app_path = File.expand_path("../../..", __FILE__)
+ Prometheus::Client.config.data_store = Prometheus::Client::DataStores::DirectFileStore.new(dir: "#{app_path}/tmp/prometheus/")
+ store_settings[:aggregation] = :most_recent
+
+ # Clean up old metric files
+ Dir["#{app_path}/tmp/prometheus/*.bin"].each do |file_path|
+ File.unlink(file_path)
+ end
+end
 
 prometheus = Prometheus::Client.registry
 
 $metrics = {
- ratelimit_remaining: prometheus.gauge(:ratelimit_remaining, "Remaining GitHub ratelimit."),
+ ratelimit_remaining: prometheus.gauge(:ratelimit_remaining, store_settings: store_settings, docstring: "Remaining GitHub ratelimit."),
 }

config/puma.rb

@@ -23,3 +23,12 @@
 if ENV["LOG_ENABLED"]
  stdout_redirect("#{app_path}/log/puma-stdout.log", "#{app_path}/log/puma-stderr.log", true)
 end
+
+if ENV["WEB_CONCURRENCY"]
+ on_worker_shutdown do |index|
+ # Delete stale metric files on worker shutdown
+ Dir["#{app_path}/tmp/prometheus/*___#{Process.pid}.bin"].each do |file_path|
+ File.unlink(file_path)
+ end
+ end
+end