Send CloudWatch metics to Mackerel host metrics using Amazon Lambda.

cloudwatch2mackerel_host_metrics.py

# -*- coding: utf-8 -*-

import boto3, os, json, calendar
from base64 import b64decode
from datetime import datetime, timedelta
from urllib2 import Request, urlopen

os.environ['TZ'] = 'Asia/Tokyo'
mackerel_url = "https://mackerel.io/api/v0/tsdb"
encrypted_mackerel_api_key = "<ENCRYPTED_API_KEY>"
kms = boto3.client('kms')
api_key = kms.decrypt(CiphertextBlob=b64decode(encrypted_mackerel_api_key))['Plaintext']

def get_metric_value(namespace, metric_name, dimensions, stats, unit):

    dm = []
    for dimension in dimensions:
        dm.append({'Name': dimension["name"], 'Value': dimension["value"]})
    print dm
    end = datetime.utcnow()
    start = end + timedelta(minutes=-30)
    client = boto3.client('cloudwatch')
    response = client.get_metric_statistics(
        Namespace=namespace,
        MetricName=metric_name,
        Dimensions=dm,
        StartTime=start.strftime("%Y-%m-%dT%H:%M:%SZ"),
        EndTime=end.strftime("%Y-%m-%dT%H:%M:%SZ"),
        Period=60,
        Statistics=[
            stats,
        ],
        Unit=unit
    )
    if str(response["ResponseMetadata"]["HTTPStatusCode"]) != "200":
        return False
    if len(response["Datapoints"]) == 0:
        return False
    return sorted(response["Datapoints"], key=lambda x:x['Timestamp'], reverse=True)[0]

def build_params(host_id, metric_name, time, value):
  return json.dumps(
    [{
      "hostId": host_id,
      "name": metric_name,
      "time": time,
      "value": value
    }]
  )

def post_mackerel(url, api_key, params, retry=5, wait=5):
    retry_count = 0
    response = None
    while True:
        try:
            req = Request(url, params)
            req.add_header("X-Api-Key", api_key)
            req.add_header("Content-Type", "application/json")
            response = urlopen(req)
        except Exception, e:
            print e
        finally:
            if response is not None:
                if response.getcode() == 200:
                    return True
            retry_count += 1
            if retry_count >= retry:
                return False
            time.sleep(wait)

# main
def lambda_handler(event, context):

    for input in event:
        mackerel = input['mackerel']
        cloudwatch = input['cloudwatch']
        url = mackerel_url

        metric = get_metric_value(
            cloudwatch["namespace"],
            cloudwatch["metric_name"],
            cloudwatch["dimensions"],
            cloudwatch["stats"],
            cloudwatch["unit"]
        )
        if metric is False:
            continue
        params = build_params(
            mackerel["host_id"],
            mackerel["metric_name"],
            calendar.timegm(metric["Timestamp"].timetuple()),
            metric[cloudwatch["stats"]]
        )
        result = post_mackerel(url, api_key, params)
        if result is False:
            continue