Since AWS Lambda gained popularity in 2014, the use of code implemented as functions has become increasingly popular. In some cases, there is even the option to build a whole application using a FaaS approach; in other cases, the approach is used to solve specific requirements.

Code deployed in the form of functions is executed when an event occurs. Once the event happens, the code is executed, and the function is then shut down. For that reason, functions are stateless by nature, since there is no state or context to share with other applications.

A FaaS is ephemeral, meaning that when a function needs to be executed, the cloud provider will automatically provision an environment using the metadata associated with the function. This will scale depending on the processing needs, and, once the processing has finished, the execution environment will be destroyed, as shown in the following diagram:

Implementing code using a FaaS approach will provide you with the following benefits:

• You won't have to worry about host configuration
• Transparent scale-up on demand
• Automatic spin up/down
• You will only pay for what you use