Reducing operational costs is one of the major advantages of a serverless solution. However, costs in a cloud computing environment need to be closely monitored in order to avoid surprises.

AWS provides a billing console for monitoring and estimating costs. It also provides billing alarms when AWS costs go over a certain threshold. These are very useful tools for keeping the cost within the allocated budget.

Costs for AWS Lambda are based on usage and charged according to the number of requests and the duration [lambda_pricing]. At the time of writing AWS provides a generous free tier of 1 million free requests and 400,000 GB-seconds of compute time per month. This makes a test suite based on a serverless architecture particularly attractive as it can be used with very little operational costs. However, increasing the memory and the timeout settings of the lambda function also increases the costs so these need to be factored in.