Create a monthly cost budget (no alerts needed, value can be arbitrary).
Configure and e-mail or domain in SES to match the address to be sent from.
Put account number in production.json and project.json.
Create dynamo db table, billing_history, String PK month, Number SK timestamp
Create ViewBudget Policy: budget, read, view budget, all resources.
Create BillingHistoryReadWrite, DynamoDB: "dynamodb:BatchGetItem", "dynamodb:BatchWriteItem", "dynamodb:PutItem", "dynamodb:GetItem", "dynamodb:Query", "dynamodb:UpdateItem" Add ARN. arn:aws:dynamodb:eu-west-1:xxx:table/billing_history
Create SendEmail, SES: "ses:SendEmail", "ses:SendTemplatedEmail", "ses:SendRawEmail"
Find role created (billing-alerts_lambda_function) add above policies
Create CloudWatch trigger.
CloudFormation stack available at: https://billing-alerts-lambda.s3-eu-west-1.amazonaws.com/billing-alerts.yml