Merge pull request #10 from eheydrick/check_conns

Add new plugin for checking postgres connections

Author: eheydrick

CHANGELOG.md

@@ -4,6 +4,8 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 This CHANGELOG follows the format listed at [Keep A Changelog](http://keepachangelog.com/)
 
 ## [Unreleased]
+### Added
+- Add new plugin `check-postgres-connections` that checks the number of connections to a DB
 
 ## [0.0.7] - 2015-12-10
 ### Changed

README.md

@@ -1,6 +1,6 @@
 ## Sensu-Plugins-postgres
 
-[ ![Build Status](https://travis-ci.org/sensu-plugins/sensu-plugins-postgres.svg?branch=master)](https://travis-ci.org/sensu-plugins/sensu-plugins-postgres)
+[![Build Status](https://travis-ci.org/sensu-plugins/sensu-plugins-postgres.svg?branch=master)](https://travis-ci.org/sensu-plugins/sensu-plugins-postgres)
 [![Gem Version](https://badge.fury.io/rb/sensu-plugins-postgres.svg)](http://badge.fury.io/rb/sensu-plugins-postgres)
 [![Code Climate](https://codeclimate.com/github/sensu-plugins/sensu-plugins-postgres/badges/gpa.svg)](https://codeclimate.com/github/sensu-plugins/sensu-plugins-postgres)
 [![Test Coverage](https://codeclimate.com/github/sensu-plugins/sensu-plugins-postgres/badges/coverage.svg)](https://codeclimate.com/github/sensu-plugins/sensu-plugins-postgres)
@@ -10,6 +10,7 @@
 
 ## Files
  * bin/check-postgres-alive.rb
+ * bin/check-postgres-connections.rb
  * bin/metric-postgres-dbsize.rb
  * bin/metric-postgres-statsbgwriter.rb
  * bin/metric-postgres-statstable.rb

bin/check-postgres-connections.rb

@@ -0,0 +1,119 @@
+#!/usr/bin/env ruby
+#
+# check-postgres-connections
+#
+# DESCRIPTION:
+#   This plugin checks the number of connections to a postgresql database and
+#   alerts when the number or percent crosses a threshold. Defaults to checking
+#   number of connections unless the --percentage flag is used in which case the
+#   percentage of max connections is checked.
+#
+# OUTPUT:
+#   plain-text
+#
+# PLATFORMS:
+#   Linux
+#
+# DEPENDENCIES:
+#   gem: pg
+#   gem: sensu-plugin
+#
+# USAGE:
+#   # warn when connections hit 250, critical when 400
+#   check-postgres-connections.rb -u db_user -p db_pass -h db_host -d db -w 250 -c 400
+#   # warn when connections hit 80%, critical when 95%
+#   check-postgres-connections.rb -u db_user -p db_pass -h db_host -d db -w 80 -c 95 --percentage
+#
+# NOTES:
+#
+# LICENSE:
+#   Copyright 2016, Eric Heydrick <eheydrick@gmail.com>
+#   Released under the same terms as Sensu (the MIT license); see LICENSE
+#   for details.
+#
+
+require 'sensu-plugin/check/cli'
+require 'pg'
+
+class CheckPostgresConnections < Sensu::Plugin::Check::CLI
+  option :user,
+         description: 'Postgres User',
+         short: '-u USER',
+         long: '--user USER'
+
+  option :password,
+         description: 'Postgres Password',
+         short: '-p PASS',
+         long: '--password PASS'
+
+  option :hostname,
+         description: 'Hostname to login to',
+         short: '-h HOST',
+         long: '--hostname HOST',
+         default: 'localhost'
+
+  option :port,
+         description: 'Database port',
+         short: '-P PORT',
+         long: '--port PORT',
+         default: 5432
+
+  option :db,
+         description: 'Database name',
+         short: '-d DB',
+         long: '--db DB',
+         default: 'postgres'
+
+  option :warning,
+         description: 'Warning threshold number or % of connections. (default: 200 connections)',
+         short: '-w WARNING',
+         long: '--warning CRITICAL',
+         default: 200,
+         proc: proc(&:to_i)
+
+  option :critical,
+         description: 'Critical threshold number or % of connections. (default: 250 connections)',
+         short: '-c CRITICAL',
+         long: '--critical CRITICAL',
+         default: 250,
+         proc: proc(&:to_i)
+
+  option :use_percentage,
+         description: 'Use percentage of max connections used instead of the absolute number of connections',
+         short: '-a',
+         long: '--percentage',
+         boolean: true,
+         default: false
+
+  def run
+    begin
+      con = PG::Connection.new(config[:hostname], config[:port], nil, nil, config[:db], config[:user], config[:password])
+      max_conns = con.exec('SHOW max_connections').getvalue(0, 0).to_i
+      current_conns = con.exec('SELECT count(*) from pg_stat_activity').getvalue(0, 0).to_i
+    rescue PG::Error => e
+      unknown "Unable to query PostgreSQL: #{e.message}"
+    end
+
+    percent = (current_conns.to_f / max_conns.to_f * 100).to_i
+
+    if config[:use_percentage]
+      message = "PostgreSQL connections at #{percent}%, #{current_conns} out of #{max_conns} connections"
+      if percent >= config[:warning]
+        warning message
+      elsif percent >= config[:critical]
+        critical message
+      else
+        ok "PostgreSQL connections under threshold: #{percent}%, #{current_conns} out of #{max_conns} connections"
+      end
+    else
+      message = "PostgreSQL connections at #{current_conns} out of #{max_conns} connections"
+      if current_conns >= config[:warning]
+        warning message
+      elsif current_conns >= config[:critical]
+        critical message
+      else
+        ok "PostgreSQL connections under threshold: #{current_conns} out of #{max_conns} connections"
+      end
+    end
+  end
+end