Class: MonitorType

Inherits:
Object
  • Object
show all
Defined in:
lib/monitor_type.rb

Overview

Base class for Monitors

Given that this is a DSL, it extracts named parameters from a hash in order to provide more precise reporting of errors, without spewing syntax errors at a user

Direct Known Subclasses

MonitorTypeThreshold

Instance Method Summary collapse

Constructor Details

#initialize(params) ⇒ MonitorType

Check that all required parameters have been passed in Make sure that any errors encountered are reported in a way that fixing the error is made easier



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# File 'lib/monitor_type.rb', line 28

def initialize(params)
  if params[:name].nil?
    string = '*** Monitor parameter missing, name' \
             '*** :name => <name of monitor>'
    fail MonitorTypeMustHaveNameError, string
  end
  @params = params
  @block = params[:block] unless params[:block].nil?
  @name = params[:name]
  @email = params[:email]
  @url = params[:url] unless params[:url].nil?

  if !@email.nil?
    # Sender email address from ENV allows for a single sender across all alerts
    # Checking params before ENV allows a particular entry to be different
    if params[:email_sender].nil?
      if ENV['EMAIL_SENDER'].nil?
        string = '*** Alert parameter missing, email_sender' \
                  '*** An email recipient has been specified for monitor, ' \
                  "#{@name}, but no email sender has been specified" \
                  '*** :email_sender => <email of sender>' \
                  '*** or, a catch all environment variable' \
                  '*** EMAIL_SENDER=<email of sender>'

        fail MonitorTypeMustHaveSenderEmailAddressForEmailAlertError, string
      else
        @sender_email = ENV['EMAIL_SENDER']
      end
    else
      @sender_email = params[:admin_email]
    end
  end

  cron_string = params[:cron] || '0 1 * * *'
  @cron = CronParser.new(cron_string)
  @next = Time.now - 1

  log "Loaded Monitor, #{@name}."
end

Instance Method Details

#alert(string) ⇒ Object

Called when a monitor has been tripped

Parameters:

  • string (String) —

    A description of the trip that occurred



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# File 'lib/monitor_type.rb', line 104

def alert(string)
  body = "#{@name} tripped.\n#{string}"
  puts '*** '
  if !@email.nil?
    AlertEmail.new(@sender_email, @email, body).send
    puts "Emailed, #{@email}"
  else
    puts body
  end
end

#extract_params ⇒ Object

Overload this method if any parameters should be checked in context



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# File 'lib/monitor_type.rb', line 69

def extract_params
end

#process ⇒ Object

Check if the monitor has tripped



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# File 'lib/monitor_type.rb', line 81

def process
  fail 'Method needs to be overridden'
end

#run ⇒ Object

An extention of the main run loop. Each monitor is responsible for knowing when it should run, so this function is called pretty much continuosuly.



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# File 'lib/monitor_type.rb', line 88

def run
  return unless Time.now > @next

  @next = @cron.next(Time.now)
  log "Monitor, #{@name}, next run time, #{@next}"
  extract_params
  setup
  process
  teardown
rescue MonitorTypeExceptionHandled => e
  alert(e.message)
end

#setup ⇒ Object

Overload this method if any parameters should be checked in context



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# File 'lib/monitor_type.rb', line 73

def setup
end

#teardown ⇒ Object

Overload this method if any parameters should be checked in context



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# File 'lib/monitor_type.rb', line 77

def teardown
end