特定の Amazon EC2 インスタンスに関する情報の取得

次の例では、指定した Amazon EC2 インスタンスの状態を一覧表示します。

# Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
# SPDX - License - Identifier: Apache - 2.0

require 'aws-sdk-ec2'

# Lists the state of an Amazon Elastic Compute Cloud (Amazon EC2) instance.
#
# Prerequisites:
#
# - An Amazon EC2 instance.
#
# @param ec2_client [Aws::EC2::Client] An initialized EC2 client.
# @param instance_id [String] The ID of the instance.
# @example
#   list_instance_state(
#     Aws::EC2::Resource.new(region: 'us-east-1'),
#     'i-123abc'
#   )
def list_instance_state(ec2_client, instance_id)
  response = ec2_client.describe_instances(
    instance_ids: [instance_id]
  )
  if response.count.zero?
    puts 'No matching instance found.'
  else
    instance = response.reservations[0].instances[0]
    puts "The instance with ID '#{instance_id}' is '#{instance.state.name}'."
  end
rescue StandardError => e
  puts "Error getting information about instance: #{e.message}"
end

# Full example call:
def run_me
  instance_id = ''
  region = ''
  # Print usage information and then stop.
  if ARGV[0] == '--help' || ARGV[0] == '-h'
    puts 'Usage:   ruby ec2-ruby-example-list-state-instance-i-123abc.rb ' \
      'INSTANCE_ID REGION'
    puts 'Example: ruby ec2-ruby-example-list-state-instance-i-123abc.rb ' \
      'i-123abc us-east-1'
    exit 1
  # If no values are specified at the command prompt, use these default values.
  elsif ARGV.count.zero?
    instance_id = 'i-123abc'
    region = 'us-east-1'
  # Otherwise, use the values as specified at the command prompt.
  else
    instance_id = ARGV[0]
    region = ARGV[1]
  end

  ec2_client = Aws::EC2::Client.new(region: region)
  list_instance_state(ec2_client, instance_id)
end

run_me if $PROGRAM_NAME == __FILE__