Syntax      = { Production } .
Production  = production_name "=" [ Expression ] "." .
Expression  = Term { "|" Term } .
Term        = Factor { Factor } .
Factor      = production_name | token [ "…" token ] | Group | Option | Repetition .
Group       = "(" Expression ")" .
Option      = "[" Expression "]" .
Repetition  = "{" Expression "}" .
</pre>

<p>
Productions are expressions constructed from terms and the following

  // the affinity expressions specified by this field, but it may choose
  // a node that violates one or more of the expressions. The node that is
  // most preferred is the one with the greatest sum of weights, i.e.
  // for each node that meets all of the scheduling requirements (resource
  // request, requiredDuringScheduling affinity expressions, etc.),

- Improved handling of jsonpath expressions for `kubectl wait --for`. It is now possible to use simple filter expressions which match on a field's content. ([#118748](https://github.com/kubernetes/kubernetes/pull/118748), [@andreaskaris](https://github.com/andreaskaris))

- Added authorization check support to the CEL expressions of ValidatingAdmissionPolicy via a `authorizer`

- The "value" part in the `wait --for=jsonpath='{expression}'[=value]` is now
  optional. If the value is not provided i.e., the command looks like `wait --for=jsonpath='{expression}'`
  then the wait condition is interpreted as matched when the expression returns

- To enhance usability and developer experience, CRD validation rules now support direct use of (CEL) reserved keywords as field names in object validation expressions for existing expressions in storage, will fully support runtime in next release for compatibility concern. ([#126188](https://github.com/kubernetes/kubernetes/pull/126188), [@cici37](https://github.com/cici37)) [SIG API Machinery and Testing]

- When configuring a JWT authenticator:
  
  If `username.expression` used 'claims.email', then 'claims.email_verified' must have been used in `username.expression` or `extra[*].valueExpression` or `claimValidationRules[*].expression`. An example claim validation rule expression that matches the validation automatically applied when `username.claim` is set to 'email' is 'claims.?email_verified.orValue(true)'.

- Fixed an error processing watch events when running skewed apiservers ([#73482](https://github.com/kubernetes/kubernetes/pull/73482), [@liggitt](https://github.com/liggitt))
- jsonpath expressions containing `[start:end:step]` slice are now evaluated correctly ([#73149](https://github.com/kubernetes/kubernetes/pull/73149), [@liggitt](https://github.com/liggitt))

## Changelog since v1.26.8

## Changes by Kind

### API Change

- Fixed a bug where CEL expressions in CRD validation rules would incorrectly compute a high estimated cost for functions that return strings, lists or maps.

- CEL CRD validation expressions may now reference existing object state using the identifier `oldSelf`. ([#108073](https://github.com/kubernetes/kubernetes/pull/108073), [@benluddy](https://github.com/benluddy))