availability.py

#!/usr/bin/env python3

"""
requires python 3.7
"""

import argparse
import re
import sys
import datetime

import boto3

UUID_REGEX = "^[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}$"
cloudwatch = boto3.client('cloudwatch')


def uuid_type(s):
    if not re.compile(UUID_REGEX).match(s):
        raise argparse.ArgumentTypeError(f"Does not match r\"{UUID_REGEX}\"")
    return s


if __name__ == '__main__':
    name = sys.argv[0].split('/')[-1]

    end_date = datetime.datetime.utcnow()
    start_date = end_date - datetime.timedelta(days=7)

    cli = argparse.ArgumentParser(
        description=f"`{name}` determines the availability of your service based on a route53 health check."
    )
    cli.add_argument(
        "-s",
        "--start-date",
        dest="start_date",
        help="The Start Date - format YYYY-MM-DD",
        default=start_date,
        type=datetime.datetime.fromisoformat
    )
    cli.add_argument(
        "-e",
        "--end-date",
        dest="end_date",
        help="The End Date format YYYY-MM-DD (Inclusive)",
        default=end_date,
        type=datetime.datetime.fromisoformat
    )
    cli.add_argument(
        "health_check_id",
        type=uuid_type,
        help="The UUID of your application's health check"
    )
    options = cli.parse_args(sys.argv[1:])
    period = int((options.end_date - options.start_date).total_seconds())

    print(f"start date:\t{options.start_date.isoformat()}")
    print(f"end date:\t{options.end_date.isoformat()}")
    print(f"period:\t\t{period}s")

    data = cloudwatch.get_metric_data(
        MetricDataQueries=[
            {
                'Id': "sum",
                'MetricStat': {
                    'Metric': {
                        'Namespace': 'AWS/Route53',
                        'MetricName': 'HealthCheckPercentageHealthy',
                        'Dimensions': [
                            {
                                'Name': 'HealthCheckId',
                                'Value': options.health_check_id
                            },
                        ]
                    },
                    'Period': period,
                    'Stat': 'Sum',
                },
                'ReturnData': True
            },
            {
                'Id': "sample_count",
                'MetricStat': {
                    'Metric': {
                        'Namespace': 'AWS/Route53',
                        'MetricName': 'HealthCheckPercentageHealthy',
                        'Dimensions': [
                            {
                                'Name': 'HealthCheckId',
                                'Value': options.health_check_id
                            },
                        ]
                    },
                    'Period': period,
                    'Stat': 'SampleCount',
                },
                'ReturnData': True
            },
        ],
        StartTime=options.start_date,
        EndTime=options.end_date
    )['MetricDataResults']
    metric_sum = next(ele for ele in data if ele['Id'] == 'sum')['Values'][0]
    metric_sample_count = next(ele for ele in data if ele['Id'] == 'sample_count')['Values'][0]
    print(f"availability:\t{metric_sum / metric_sample_count}")