extension

Overview ¶

Package extension provides the public surface for writing Kuadrant policy extensions.

An extension is a lightweight controller process which connects (via the grpc sub‑package) to the Kuadrant extension service over a unix domain socket. Through this connection an extension can:

1. Resolve CEL expressions against an in‑memory view of policies and gateway topology (see the cel/ext package for available functions like findGateways and findAuthPolicies).
2. Register mutators that enrich policy documents with computed data.
3. Subscribe to evaluation or object change events and trigger reconciliation.
4. Reconcile and persist Kubernetes objects related to a custom policy kind.

Typical Usage

b, log := controller.NewBuilder("my-policy")
b.WithScheme(scheme).
  For(&myv1.MyPolicy{}).
  Watches(&corev1.Secret{}).
  WithReconciler(func(ctx context.Context, req reconcile.Request, kctx types.KuadrantCtx) (reconcile.Result, error) {
      // 1. Fetch the policy instance using kctx.Client() (available via context)
      // 2. Resolve CEL expressions:
      //    v, err := kctx.Resolve(ctx, policy, "self.findGateways()", false)
      // 3. Create/update owned objects:
      //    obj, err := kctx.ReconcileObject(ctx, existing, desired, mutateFn)
      // 4. Return standard controller-runtime reconcile.Result
      return reconcile.Result{}, err
  })
ctrl, _ := b.Build()
_ = ctrl.Start(ctx)

Sub‑packages

controller - Builder + runtime controller that wires watches, reconcile
             invocation, finalizers, gRPC subscription and event caching.
types      - Interfaces (Policy, KuadrantCtx, ReconcileFn) and helpers
             shared between implementations and the controller.
utils      - Context helper accessors for logger, client and scheme.
grpc       - Protobuf generated types and small adapters (do not edit).

See also the cel/ext package which defines CEL functions and type registry exposed to policy CEL expressions evaluated through KuadrantCtx.Resolve.