Lambda 関数を利用して、オンデマンドキャパシティ予約を実行してみた

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Effect": "Allow",
            "Principal": {
                "Service": "lambda.amazonaws.com"
            },
            "Action": "sts:AssumeRole"
        }
    ]
}

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Effect": "Allow",
            "Action": "logs:CreateLogGroup",
            "Resource": "arn:aws:logs:<region>:<account-id>:*"
        },
        {
            "Effect": "Allow",
            "Action": [
                "logs:CreateLogStream",
                "logs:PutLogEvents"
            ],
            "Resource": [
                "arn:aws:logs:<region>:<account-id>:log-group:/aws/lambda/<lambda-function-name>:*"
            ]
        },
        {
            "Effect": "Allow",
            "Action": [
                "ec2:CreateCapacityReservation",
                "ec2:DescribeCapacityReservations",
                "ec2:DescribeInstances",
                "ec2:DescribeInstanceTypes"
            ],
            "Resource": "*"
        },
        {
            "Effect": "Allow",
            "Action": "SNS:Publish",
            "Resource": "arn:aws:sns:<region>:<account-id>:<SNS-Topic-NAME>"
        }
    ]
}

import boto3
import datetime
import os

ec2_client = boto3.client('ec2', region_name='ap-northeast-1')
sns_client = boto3.client('sns')

def lambda_handler(event, context):
    instance_type = os.environ.get('INSTANCE_TYPE')
    instance_platform = os.environ.get('INSTANCE_PLATFORM')
    availability_zone = os.environ.get('AVAILABILITY_ZONE')
    instance_count = int(os.environ.get('INSTANCE_COUNT', 1))
    end_hour = int(os.environ.get('END_HOUR', 17))
    end_minute = int(os.environ.get('END_MINUTE', 0))
    sns_topic_arn = os.environ.get('SNS_TOPIC_ARN')

    if instance_type is None:
        raise ValueError("INSTANCE_TYPE environment variable is not set.")
    if instance_platform is None:
        raise ValueError("INSTANCE_PLATFORM environment variable is not set.")
    if availability_zone is None:
        raise ValueError("AVAILABILITY_ZONE environment variable is not set.")
    if sns_topic_arn is None:
        raise ValueError("SNS_TOPIC_ARN environment variable is not set.")

    now = datetime.datetime.utcnow()
    japan_time = now + datetime.timedelta(hours=9)
    end_time = japan_time.replace(hour=end_hour, minute=end_minute, second=0, microsecond=0)
    if end_time < japan_time:
        end_time += datetime.timedelta(days=1)
    end_time_utc = end_time - datetime.timedelta(hours=9)

    try:
        describe_instance_types = ec2_client.describe_instance_types(InstanceTypes=[instance_type])
        ebs_optimized_supported = describe_instance_types['InstanceTypes'][0]['EbsInfo']['EbsOptimizedSupport'] != 'unsupported'
    except KeyError:
        ebs_optimized_supported = False

    create_capacity_reservation_params = {
        "InstanceType": instance_type,
        "InstancePlatform": instance_platform,
        "AvailabilityZone": availability_zone,
        "Tenancy": 'default',
        "InstanceCount": instance_count,
        "EndDate": end_time_utc,
        "EndDateType": 'limited',
        "InstanceMatchCriteria": 'open'
    }

    if ebs_optimized_supported:
        create_capacity_reservation_params["EbsOptimized"] = True

    try:
        response = ec2_client.create_capacity_reservation(**create_capacity_reservation_params)
        return {
            'statusCode': 200,
            'body': f'Capacity reservation created for {instance_count} instances until {end_time_utc} (UTC)'
        }
    except ec2_client.exceptions.ClientError as e:
        error_message = f'Failed to create capacity reservation: {str(e)}'
        sns_client.publish(
            TopicArn=sns_topic_arn,
            Subject='EC2 Capacity Reservation Failure',
            Message=error_message
        )
        return {
            'statusCode': 500,
            'body': error_message
        }