Version 0.1.0

.gitignore

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+/assets/
+/Gemfile.lock

.rubocop.yml

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+AllCops:
+  SuggestExtensions: false
+  TargetRubyVersion: 3.2
+
+Metrics/AbcSize:
+  Enabled: false
+
+Metrics/MethodLength:
+  Enabled: false
+
+Metrics/ClassLength:
+  Enabled: false
+
+Metrics/CyclomaticComplexity:
+  Enabled: false
+
+Metrics/PerceivedComplexity:
+  Enabled: false
+
+Layout/LineLength:
+  Enabled: false
+
+Style/Documentation:
+  Enabled: false
+
+Style/StringLiterals:
+  Enabled: true
+  EnforcedStyle: single_quotes
+
+Style/StringLiteralsInInterpolation:
+  Enabled: true
+  EnforcedStyle: double_quotes

.ruby-version

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+3.2.2

Dockerfile.debian10

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+FROM sensu-ruby32-runtime-3.2.2-debian10:0.1.2
+ARG ASSET_GEM=sensu-plugins-chrony
+ARG GIT_REF=9247833830bf37d03456146588590333a447416a
+ARG GIT_REPO=https://github.com/opsone/sensu-plugins-chrony.git
+
+WORKDIR /assets/build/
+RUN apt-get update && apt-get install -y git
+RUN printf "source 'https://rubygems.org'\n\ngem '%s', git: '%s' , ref: '%s'\n" ${ASSET_GEM} ${GIT_REPO} ${GIT_REF} | tee Gemfile
+RUN bundle install --path=lib/ --binstubs=bin/ --standalone
+RUN tar -czf /assets/${ASSET_GEM}.tar.gz -C /assets/build/ .

Dockerfile.debian11

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+FROM sensu-ruby32-runtime-3.2.2-debian11:0.1.2
+ARG ASSET_GEM=sensu-plugins-chrony
+ARG GIT_REF=9247833830bf37d03456146588590333a447416a
+ARG GIT_REPO=https://github.com/opsone/sensu-plugins-chrony.git
+
+WORKDIR /assets/build/
+RUN apt-get update && apt-get install -y git
+RUN printf "source 'https://rubygems.org'\n\ngem '%s', git: '%s' , ref: '%s'\n" ${ASSET_GEM} ${GIT_REPO} ${GIT_REF} | tee Gemfile
+RUN bundle install --path=lib/ --binstubs=bin/ --standalone
+RUN tar -czf /assets/${ASSET_GEM}.tar.gz -C /assets/build/ .

Gemfile

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+# frozen_string_literal: true
+
+source 'https://rubygems.org'
+
+# Specify your gem's dependencies in sensu-plugins-postgres.gemspec
+gemspec
+
+gem 'rake', '~> 13.0'
+gem 'rubocop', '~> 1.21'

Rakefile

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+# frozen_string_literal: true
+
+require 'bundler/gem_tasks'
+require 'rubocop/rake_task'
+
+RuboCop::RakeTask.new
+
+task default: :rubocop
+
+task :build_assets do
+  version = Sensu::Plugins::Chrony::VERSION
+
+  %w[debian11 debian10].each do |platform|
+    `docker build -t ruby-plugin-#{platform} -f Dockerfile.#{platform} .`
+    `docker run -v "$PWD/assets:/tmp/assets" ruby-plugin-#{platform} cp /assets/sensu-plugins-chrony.tar.gz /tmp/assets/sensu-plugins-chrony_#{version}_#{platform}_linux_amd64.tar.gz`
+    `docker rm $(docker ps -a -q --filter ancestor=ruby-plugin-#{platform})`
+    `docker rmi ruby-plugin-#{platform}`
+  end
+
+  `cd assets && shasum -a 512 ./*.tar.gz > sensu-plugins-chrony_#{version}_sha512-checksums.txt`
+end

bin/check-chrony.rb

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+#!/usr/bin/env ruby
+# frozen_string_literal: true
+
+require 'sensu-plugin/check/cli'
+
+class CheckChrony < Sensu::Plugin::Check::CLI
+  option :chronyc_cmd,
+         description: 'Path to chronyc executable (default: /usr/bin/chronyc)',
+         short: '-c <PATH>',
+         long: '--chronyc-cmd <PATH>',
+         default: '/usr/bin/chronyc'
+
+  option :warn_offset,
+         description: 'Warn if OFFSET exceeds current offset (ms)',
+         long: '--warn-offset <OFFSET>',
+         proc: proc(&:to_f),
+         default: 50
+
+  option :crit_offset,
+         description: 'Critical if OFFSET exceeds current offset (ms)',
+         long: '--crit-offset <OFFSET>',
+         proc: proc(&:to_f),
+         default: 100
+
+  option :warn_stratum,
+         description: 'Warn if STRATUM exceeds current stratum',
+         long: '--warn-stratum <STRATUM>',
+         proc: proc(&:to_i),
+         default: 10
+
+  option :crit_stratum,
+         description: 'Critical if STRATUM exceeds current stratum',
+         long: '--crit-stratum <STRATUM>',
+         proc: proc(&:to_i),
+         default: 16
+
+  def run
+    stratum = nil
+    offset = nil
+    status = nil
+
+    `#{config[:chronyc_cmd]} tracking`.each_line do |line|
+      case line.downcase
+      when /^stratum\s*:\s*(\d+)$/
+        stratum = Regexp.last_match(1).to_i
+      when /^last offset\s*:\s*([\-\+]?[.\d]+)\s*seconds$/
+        # convert from seconds to milliseconds
+        offset = Regexp.last_match(1).to_f * 1000
+      when /^leap status\s*:\s*(.*?)$/
+        status = Regexp.last_match(1)
+      end
+    end
+
+    if stratum
+      msg = "NTP stratum is #{stratum}"
+
+      if stratum >= config[:crit_stratum]
+        msg += ", expected < #{config[:crit_stratum]}"
+        critical msg
+      elsif stratum >= config[:warn_stratum]
+        msg += ", expected < #{config[:warn_stratum]}"
+        warning msg
+      else
+        ok msg
+      end
+    else
+      unknown 'Failed to look up NTP stratum'
+    end
+
+    if offset
+      msg = "NTP offset is #{offset.round(4)}ms"
+
+      if offset >= config[:crit_offset] || offset <= -config[:crit_offset]
+        msg += ", expected > -#{config[:crit_offset]} and < #{config[:crit_offset]}"
+        critical msg
+      elsif offset >= config[:warn_offset] || offset < -config[:warn_offset]
+        msg += ", expected > -#{config[:warn_offset]} and < #{config[:warn_offset]}"
+        warning msg
+      else
+        ok msg
+      end
+    else
+      unknown 'Failed to look up NTP offset'
+    end
+
+    if status
+      msg = "NTP status is '#{status}'"
+
+      if status != 'normal'
+        msg += ', expected \'Normal\''
+        critical msg
+      else
+        ok msg
+      end
+    else
+      unknown 'Failed to look up NTP status'
+    end
+  end
+
+  private
+
+  def send_client_socket(data)
+    sock = UDPSocket.new
+    sock.send("#{data}\n", 0, '127.0.0.1', 3030)
+  end
+
+  def send_ok(check_name, msg)
+    event = {
+      'name' => check_name,
+      'status' => 0,
+      'output' => "#{self.class.name} OK: #{msg}"
+    }
+    send_client_socket(event.to_json)
+  end
+
+  def send_warning(check_name, msg)
+    event = {
+      'name' => check_name,
+      'status' => 1,
+      'output' => "#{self.class.name} WARNING: #{msg}"
+    }
+    send_client_socket(event.to_json)
+  end
+
+  def send_critical(check_name, msg)
+    event = {
+      'name' => check_name,
+      'status' => 2,
+      'output' => "#{self.class.name} CRITICAL: #{msg}"
+    }
+    send_client_socket(event.to_json)
+  end
+
+  def send_unknown(check_name, msg)
+    event = {
+      'name' => check_name,
+      'status' => 3,
+      'output' => "#{self.class.name} UNKNOWN: #{msg}"
+    }
+    send_client_socket(event.to_json)
+  end
+end

lib/sensu/plugins/chrony.rb

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+# frozen_string_literal: true
+
+require_relative 'chrony/version'
+
+module Sensu
+  module Plugins
+    module Chrony
+      class Error < StandardError; end
+    end
+  end
+end

lib/sensu/plugins/chrony/version.rb

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+# frozen_string_literal: true
+
+module Sensu
+  module Plugins
+    module Chrony
+      VERSION = '0.1.0'
+    end
+  end
+end

sensu-plugins-chrony.gemspec

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+# frozen_string_literal: true
+
+require_relative 'lib/sensu/plugins/chrony'
+
+Gem::Specification.new do |spec|
+  spec.name = 'sensu-plugins-chrony'
+  spec.version = Sensu::Plugins::Chrony::VERSION
+  spec.authors = ['Kevyn Lebouille']
+  spec.email = ['[email protected]']
+
+  spec.summary = 'This plugin provides facilities for monitoring Chrony NTP'
+  spec.homepage = 'https://github.com/opsone/sensu-plugins-chrony'
+  spec.required_ruby_version = '>= 3.2.0'
+
+  spec.metadata['allowed_push_host'] = "TODO: Set to your gem server 'https://example.com'"
+
+  spec.metadata['homepage_uri'] = spec.homepage
+  spec.metadata['source_code_uri'] = 'https://github.com/opsone/sensu-plugins-chrony'
+  spec.metadata['changelog_uri'] = 'https://github.com/opsone/sensu-plugins-chrony/CHANGELOG.md'
+
+  # Specify which files should be added to the gem when it is released.
+  # The `git ls-files -z` loads the files in the RubyGem that have been added into git.
+  spec.files = Dir.chdir(__dir__) do
+    `git ls-files -z`.split("\x0").reject do |f|
+      (File.expand_path(f) == __FILE__) || f.start_with?(*%w[test/ spec/ features/ .git .circleci appveyor])
+    end
+  end
+  spec.bindir = 'bin'
+  spec.executables = spec.files.grep(%r{\Abin/}) { |f| File.basename(f) }
+  spec.require_paths = ['lib']
+
+  # Uncomment to register a new dependency of your gem
+  spec.add_dependency 'sensu-plugin', '~> 4.0'
+
+  # For more information and examples about making a new gem, check out our
+  # guide at: https://bundler.io/guides/creating_gem.html
+end