Module everywhere 

CEL everywhere (DW-059).

One CEL surface across four use-sites, following the APISIX expr/Kong expressions-router precedent of a single expression language rather than a bespoke DSL per feature.

Use-sites

1. Expression matchers in routes – a CEL expression that evaluates to a bool; if true, the route matches.
2. Header/transform logic – a CEL expression that evaluates to a string; the result is used as the header value.
3. Rate-limit key derivation – a CEL expression that evaluates to a string; the result is used as the rate-limit key (e.g. request.headers["x-api-key"]).
4. Policy conditions – a CEL expression that evaluates to a bool; if true, the policy applies.

Request context

All four use-sites share the same request context: a request variable with path, method, headers, query, host fields. This is the standard CEL request variable that the gateway populates per-request.

Feature gate

The cel cargo feature must be enabled (this module builds on the DW-058 CEL engine).

Structs

HeaderTransform

A CEL-based header transform expression.

PolicyCondition

A CEL-based policy condition.

RateLimitKey

A CEL-based rate-limit key derivation expression.

RequestContext

The standard request context for CEL evaluation.

RouteCondition

A CEL-based route match condition.

Enums

CelUseSite

The kind of CEL use-site.

Functions

compile_for

Compile a CEL expression for a specific use-site.

evaluate_for

Evaluate a CEL program for a specific use-site, checking the result type.