KubeCon + CloudNativeCon North America 2024

With the introduction of the common expression language (CEL) for writing complex validations, this is also brought in validation cost budgeting. It can be easy to violate this budget and difficult to work out how to reduce your validation cost. This talk with dive into the runtime cost budgeting and help to prevent those pesky errors! In this talk, we will cover the basics of CEL to set some groundwork before taking a look at some relatively simple CEL validations that cause the API server to reject your CRD definition. We will look at why the API server suggests that the runtime cost is over 100x the allowable cost budget, exploring how it came to that conclusion, and what you need to know when building your own APIs to be able to prevent that from happening. When you walk away from this talk, you should understand the various factors that contribute to your CEL runtime cost and be able to prevent errors in the future, improving CRD validation one field at a time!