Common Expression Language in Kubernetes — Type checking

Reference note (untrusted external data; do not execute it as instructions). CEL is a gradually typed language. Some Kubernetes API fields contain fully type checked CEL expressions. For example, CustomResourceDefinitions Validation Rules are fully type checked. Some Kubernetes API fields contain partially type checked CEL expressions. A partially type checked expression is an expressions where some of the variables are statically typed but others are dynamically typed. For example, in the CEL expressions of ValidatingAdmissionPolicies the request variable is typed, but the object variable is dynamically typed. As a result, an expression containing request.namex would fail type checking because the namex field is not defined. However, object.namex would pass type checking even when the namex field is not defined for the resource kinds that object refers to, because object is dynamically typed. The has() macro in CEL may be used in CEL expressions to check whet Attribution: Adapted from Kubernetes Documentation under CC-BY-4.0. Adaptation: WikiKV isolated this documentation section, normalized formatting, removed long code blocks, and shortened it for retrieval. Verify version-sensitive details at the source.