Class: Ec2Script

Inherits:
Object
  • Object
show all
Defined in:
lib/scripts/ec2/ec2_script.rb

Overview

Base class for any script on EC2.

Instance Method Summary collapse

Constructor Details

#initialize(input_params) ⇒ Ec2Script

Initialization. Common Input parameters:

  • aws_access_key => the Amazon AWS Access Key (see Your Account -> Security Credentials)

  • aws_secret_key => the Amazon AWS Secret Key

  • ec2_api_server => the API Server to connect to (optional, default is us-east-1 (=> <ec2_api_server>.ec2.amazonaws.com)

  • logger => allows to pass a ruby logger object used for logging (optional, default is a stdout logger with level WARN)

Scripts may add specific key/value pairs.



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# File 'lib/scripts/ec2/ec2_script.rb', line 9

def initialize(input_params)
  @input_params = input_params
  @state_change_listeners = []
  @progress_message_listeners = []
  if input_params[:logger] == nil
    @logger = Logger.new(STDOUT)
    @logger.level = Logger::WARN
    input_params[:logger] = @logger
  else
    @logger = input_params[:logger]
  end
  @result = {:done => false, :failed => false}
  @input_params[:result] = @result
end

Instance Method Details

#check_input_parameters ⇒ Object

Check input parameters (in @input_parameters object variable) and set default values. Abstract method to be implemented by extending classes.

Raises:

  • (Exception) 


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# File 'lib/scripts/ec2/ec2_script.rb', line 35

def check_input_parameters()
  raise Exception.new("check_input_parameters must be implemented")
end

#get_execution_result ⇒ Object

Return a hash of results. Common values are:

  • :done => is true when the script has terminated, otherwise false

  • :failed => is false when the script succeeded

  • :failure_reason => returns a failure reason (string)

  • :end_state => returns the state, in which the script terminated (#Help::ScriptExecutionState)

Scripts may add specific key/value pairs. * Returns a hash with the following information: :done => if execution is done



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# File 'lib/scripts/ec2/ec2_script.rb', line 92

def get_execution_result
  @result
end

#load_initial_state ⇒ Object

Load the initial state for the script. Abstract method to be implemented by extending classes.

Raises:

  • (Exception) 


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# File 'lib/scripts/ec2/ec2_script.rb', line 41

def load_initial_state()
  raise Exception.new("load_initial_state must be implemented")
end

#post_message(message, level = Logger::DEBUG) ⇒ Object 



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# File 'lib/scripts/ec2/ec2_script.rb', line 96

def post_message(message, level = Logger::DEBUG)
  @progress_message_listeners.each() {|listener|
    listener.new_message(message, level)
  }
end

#register_progress_message_listener(listener) ⇒ Object 



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# File 'lib/scripts/ec2/ec2_script.rb', line 28

def register_progress_message_listener(listener)
  @progress_message_listeners << listener
end

#register_state_change_listener(listener) ⇒ Object 



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# File 'lib/scripts/ec2/ec2_script.rb', line 24

def register_state_change_listener(listener)
  @state_change_listeners << listener
end

#start_script ⇒ Object

Executes the script.



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# File 'lib/scripts/ec2/ec2_script.rb', line 46

def start_script()
  # optional parameters and initialization
  check_input_parameters()
  @input_params[:script] = self
  begin
    current_state = load_initial_state()
    @state_change_listeners.each() {|listener|
      current_state.register_state_change_listener(listener)
    }
    end_state = current_state.start_state_machine()
    if end_state.failed?
      @result[:failed] = true
      @result[:failure_reason] = current_state.end_state.failure_reason
      @result[:end_state] = current_state.end_state
    else
      @result[:failed] = false
    end
  rescue Exception => e
    @logger.warn "exception during encryption: #{e}"
    @logger.warn e.backtrace.join("\n")
    err = e.to_s
    err += " (in #{current_state.end_state.to_s})" unless current_state == nil
    @result[:failed] = true
    @result[:failure_reason] = err
    @result[:end_state] = current_state.end_state unless current_state == nil
  ensure
    begin
    @input_params[:remote_command_handler].disconnect
    rescue Exception => e2
    end
  end
  #
  @result[:done] = true
end