Do I need an API gateway?

If you’re using Istio, do you still need an API gateway? In the past, Istio was primarily concerned with routing traffic for services. It got traffic into the cluster and figured out where to route it to. API gateways have typically focused more on application-level functionality such as authentication, authorization, input validation, and logging.

For example, earlier in this chapter, we identified schema input validation as a process that needs to be repeated for each call and shouldn’t need to be done manually. This is important to protect against attacks that can leverage unexpected input, and it also makes for a better developer experience, providing feedback to developers sooner in the integration process. This is a common function for API gateways but is not available in Istio.

Another example of a function that is not built into Istio but is common for API gateways is logging authentication and authorization decisions and information...