monit-slack.rb

#!/usr/bin/ruby

require 'net/https'
require 'json'

slack_webhook_url=""
slack_enabled=true

def log(message)
  open('/var/log/monit.log', 'a') { |f|
    f.puts message
  }
end

if slack_enabled
  begin
    uri = URI.parse(slack_webhook_url)
    Net::HTTP.start(uri.host, uri.port, {use_ssl: true}) { |http|
      request = Net::HTTP::Post.new(uri.request_uri, {'Content-Type' => 'application/json'})
      request.body = {
        :text => "[#{ENV['MONIT_HOST']}] #{ENV['MONIT_SERVICE']} - #{ENV['MONIT_DESCRIPTION']}"
      }.to_json
      response = http.request(request)
      log("Response from Slack [#{response.code}] [#{response.body}]")
    }
  rescue Exception => e
    log("Exception while calling Slack [#{e.message}]")
  end
end