Mackerel-Webhook-Restart-Instanc_Lambda.py

import boto3, botocore, json

ec2_client = boto3.client('ec2', region_name='ap-northeast-1')
lambda_client = boto3.client('lambda', region_name='ap-northeast-1')

def validation_event(event):
    if len(event) == 0:
        print 'There is no Event source.'
        return False
    if not event.has_key("command"):
        print "There is no command."
        return False
    if not event.has_key("instance_id"):
        print "There is no instance_id."
        return False
    return True

def lambda_handler(event, context):

    if validation_event(event) is False:
        raise Exception('400: Bad Request')

    if event[u'command'] == "stop":

        ec2_client.stop_instances(
            DryRun=False,
            InstanceIds=[
                event[u'instance_id'],
            ]
        )
        print "Waiting for stopping instance: %s." % event[u'instance_id']
        ec2_client.get_waiter('instance_stopped').wait(
            DryRun=False,
            InstanceIds=[
                event[u'instance_id'],
            ],
        )

        # Invoke start lambda function
        input = {
            "instance_id": event[u'instance_id'],
            "command": "start"
        }
        try:
            response = lambda_client.invoke(
                FunctionName='Mackerel-Webhook-Restart-Instance',
                InvocationType='Event',
                Payload=json.dumps(input)
            )
        except Exception, e:
            print e
            raise Exception('500: Internal Server Error')
        if response[u'StatusCode'] != 202:
            print response
            raise Exception('500: Internal Server Error')
        return
    elif event[u'command'] == "start":

        ec2_client.start_instances(
            DryRun=False,
            InstanceIds=[
                event[u'instance_id'],
            ]
        )
        print "Waiting for starting instance: %s." % event[u'instance_id']
        ec2_client.get_waiter('system_status_ok').wait(
            DryRun=False,
            InstanceIds=[
                event[u'instance_id'],
            ]
        )

        # Invoke check lambda function
        input = {
            "instance_id": event[u'instance_id'],
            "command": "check"
        }
        try:
            response = lambda_client.invoke(
                FunctionName='Mackerel-Webhook-Restart-Instance',
                InvocationType='Event',
                Payload=json.dumps(input)
            )
        except Exception, e:
            print e
            raise Exception('500: Internal Server Error')
        if response[u'StatusCode'] != 202:
            print response
            raise Exception('500: Internal Server Error')
        return
    elif event[u'command'] == "check":
        print "Check about starting instance: %s." % event[u'instance_id']
        waiter = ec2_client.get_waiter('instance_status_ok')

        # waiting for 4 minutes (= 15 sec * 16 count)
        waiter.config.delay = 15
        waiter.config.max_attempts = 16

        try:
            waiter.wait(
                DryRun=False,
                InstanceIds=[
                    event[u'instance_id'],
                ]
            )
        except botocore.exceptions.WaiterError as e:
            # Max attempts exceeded
            # Invoke stop(restart) lambda function
            input = {
                "instance_id": event[u'instance_id'],
                "command": "stop"
            }
            response = lambda_client.invoke(
                FunctionName='Mackerel-Webhook-Restart-Instance',
                InvocationType='Event',
                Payload=json.dumps(input)
            )
        except Exception, e:
            print e
            raise Exception('500: Internal Server Error')

        return
    else:
        raise Exception('400: Bad Request')