Mackerel-Incoming-Webhook_Lambda.py

import boto3, os, json, time
from base64 import b64decode
from urllib2 import Request, urlopen

encrypted_mackerel_api_key = "ENCRYPTED_MACKEREL_API_KEY"
org_id = "ORGANIZATION_ID"

lambda_client = boto3.client('lambda', region_name='ap-northeast-1')
kms_client = boto3.client('kms')
api_key = kms_client.decrypt(CiphertextBlob=b64decode(encrypted_mackerel_api_key))['Plaintext']
os.environ['TZ'] = 'Asia/Tokyo'
mackerel_url = "https://mackerel.io/api/v0/hosts/"

def validation_event(event):
    if len(event) == 0:
        print 'There is no Evnet source.'
        return False
    if not event.has_key("body"):
        print "There is no body."
        return False

    # Check OrgID
    body = event["body"]
    if body["orgId"] != org_id:
        print "Invalid orgId."
        return False

    # Check host information
    if not body.has_key("host"):
        print "There is no host infomation."
        return False

    # Check alert information
    if not body.has_key("alert"):
        print "There is no alert infomation."
        return False
    alert = body["alert"]
    if alert["status"] == "ok" or alert["status"] == "unknown":
        print "This alert status is ok or unknown."
        return False
    if alert["metricLabel"] != "custom.ec2.status_check_failed.total":
        print "This alert is not status_check_failed.total."
        return False

    return True

def get_host_id(event):
    return event["body"]["host"]["id"]

def request_mackerel(url, method, api_key, params="{}", retry=5, wait=5):
    retry_count = 0
    response = None
    while True:
        try:
            if method == "GET":
                req = Request(url)
            else:
                req = Request(url, params)
            req.add_header("X-Api-Key", api_key)
            req.add_header("Content-Type", "application/json")
            req.get_method = lambda: method
            response = urlopen(req)
        except Exception, e:
            print e
        finally:
            if response is not None:
                if response.getcode() == 200:
                    return response.read()
            if e.getcode() == 404:
                return False
            retry_count += 1
            if retry_count >= retry:
                raise Exception('500: Internal Server Error')
            time.sleep(wait)

def lambda_handler(event, context):

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

    host_id = get_host_id(event)
    if host_id is False:
        print event
        raise Exception('400: Bad Request')

    url = mackerel_url + host_id
    result = request_mackerel(url, "GET", api_key)
    if result is False:
        raise Exception('400: Bad Request')
    root = json.loads(result)
    instance_id = root[u'host'][u'meta'][u'cloud'][u'metadata'][u'instance-id']
    print instance_id

    input = {
        "instance_id": instance_id,
        "command": "stop"
    }
    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:
        raise Exception('500: Internal Server Error')
    return