A Kubernetes preview environment is an isolated environment that allows developers to test their code at any time without worrying about how others may be affected. While implementations and use cases may vary, simulating a production environment as closely as possible is the main goal. Imagine you're part of a team developing a complex API, and you've been tasked with adding a new endpoint that relies on features within the codebase currently being optimized by one of your team members. Although your team has a development environment with seeded databases and dev versions of dependencies, you run into issues when team members want to test their optimizations at the same time as you.

Testing Kubernetes Ingress resources can be tricky, and can lead to frustration when bugs pop up in production that weren't caught during testing. This can happen for a variety of reasons, but with Ingress specifically, it often has to do with a misalignment between the data used in testing and the traffic generated in production. Tools like Postman can be a great way of generating traffic, but they have the drawback of being manually created. Not only is this unlikely to create all the needed variations for a single endpoint (different headers, different request bodies, etc.), it would be almost impossible to create all the needed variations, for all possible endpoints.