DynamoDB table WCU/RCU reservation calculator

dyanmodb_reservation_calc.py

import boto3
from datetime import datetime
from dateutil.relativedelta import relativedelta
import numpy as np

def get_table_metrics(cloudwatch_client, table_name, start_time, end_time):
    response = cloudwatch_client.get_metric_data(
        MetricDataQueries=[
            {
                'Id': 'dynamoDBWCU',
                'MetricStat': {
                    'Metric': {
                        'Namespace': 'AWS/DynamoDB',
                        'MetricName': 'ConsumedWriteCapacityUnits',
                        'Dimensions': [
                            {'Name': 'TableName', 'Value': table_name}
                        ]
                    },
                    'Period': 3600,
                    'Stat': 'Sum'
                }
            },
            {
                'Id': 'dynamoDBRCU',
                'MetricStat': {
                    'Metric': {
                        'Namespace': 'AWS/DynamoDB',
                        'MetricName': 'ConsumedReadCapacityUnits',
                        'Dimensions': [
                            {'Name': 'TableName', 'Value': table_name}
                        ]
                    },
                    'Period': 3600,
                    'Stat': 'Sum'
                }
            }
        ],
        StartTime=start_time,
        EndTime=end_time
    )
    rcu_data = next(filter(lambda r: r['Id'] == 'dynamoDBRCU', response['MetricDataResults']))
    wcu_data = next(filter(lambda r: r['Id'] == 'dynamoDBWCU', response['MetricDataResults']))
    return (rcu_data['Values'], wcu_data['Values'])

# NOTE: you must have at least one month (preferably more) of data for this to be useful
# modify this for your needs
table_name = 'SOME_TABLE'
end_time = datetime.now()
start_time = end_time - relativedelta(years=1)
cloudwatch = boto3.client('cloudwatch')

rcu_data, wcu_data = get_table_metrics(cloudwatch, table_name, start_time, end_time)
print('WCU reservations')
print('With partial usage: {}, no partial usage: {}'.format(*np.percentile(wcu_data, [32, 46])))
print('RCU reservations')
print('With partial usage: {}, no partial usage: {}'.format(*np.percentile(rcu_data, [32, 46])))