Safe Deployments

This chapter explains two core features of AWS Lambda: versions and aliases. You will also learn how to use aliases to protect against unexpected deployment problems.

Although AWS Lambda technically works like a virtualised container management system, the life-cycle for Lambda functions is quite different from that of the usual container-based applications. This might be counter-intuitive to people who are used to managed container services. Luckily, AWS SAM hides most of the underlying complexity from developers. In this chapter, you will peek under the hood just enough so you can avoid subtle mistakes. Knowing how Lambda routes requests and provisions runtime environments is also critical for getting the most out of cloud functions.

In the previous chapter, you deployed a new version of the example stack to add logging. New code was available and it responded to user requests almost immediately after deployment. This can give the wrong impression that Lambda works ...