feat: Implement Model Rewrite and Traffic Splitting Logic

apix/v1alpha2/inferencemodelrewrite_types.go

@@ -57,20 +57,25 @@ type InferenceModelRewriteSpec struct {
 	// If multiple InferenceModelRewrite resources target the same
 	// InferencePool, the controller will merge them based on precedence.
 	//
-	// **Timestamp Wins:** If two rules from different rewrites all matches,
-	// the rule from the *oldest*
-	// InferenceModelRewrite resource (determined by
-	// metadata.creationTimestamp) will be used.
+	// Across all rules specified on applicable rewrites, precedence MUST be
+	// given to the match having an "Exact" model match over a generic match
+	// (a rule with an empty `matches` array).
+	//
+	// If ties still exist across multiple InferenceModelRewrite resources (e.g.
+	// two rewrites both have an exact match for the same model), matching
+	// precedence MUST be determined by the oldest resource based on
+	// creation timestamp.
+	//
+	// If ties still exist within a single InferenceModelRewrite resource, the
+	// FIRST matching rule (in list order) is used.
 	// +required
 	Rules []InferenceModelRewriteRule `json:"rules"`
 }
 
 // InferenceModelRewriteRule defines the match criteria and corresponding action.
-//
-// A specific model name can only be matched by one rule across all
-// rules attached to the same InferencePool. If multiple rules attempt
-// to match the same model name, the oldest rule (by creationTimestamp)
-// will be the only one considered valid.
+// For details on how precedence is determined across multiple rules and
+// InferenceModelRewrite resources, see the "Precedence and Conflict Resolution"
+// section in InferenceModelRewriteSpec.
 type InferenceModelRewriteRule struct {
 	// Matches defines the criteria for matching a request.
 	// If multiple match criteria are specified, a request matches if
@@ -87,7 +92,7 @@ type InferenceModelRewriteRule struct {
 	// +optional
 	// +kubebuilder:validation:MinItems=1
 	//
-	Targets []TargetModel `json:"split,omitempty"`
+	Targets []TargetModel `json:"targets,omitempty"`
 }
 
 // TargetModel defines a weighted model destination for traffic distribution.

config/charts/inferencepool/templates/rbac.yaml

@@ -46,7 +46,7 @@ metadata:
     {{- include "gateway-api-inference-extension.labels" . | nindent 4 }}
 rules:
 - apiGroups: ["inference.networking.x-k8s.io"]
-  resources: ["inferenceobjectives"]
+  resources: ["inferenceobjectives", "inferencemodelrewrites"]
   verbs: ["get", "watch", "list"]
 - apiGroups: ["{{ (split "/" .Values.inferencePool.apiVersion)._0 }}"]
   resources: ["inferencepools"]

config/crd/bases/inference.networking.x-k8s.io_inferencemodelrewrites.yaml

@@ -74,11 +74,9 @@ spec:
                 items:
                   description: |-
                     InferenceModelRewriteRule defines the match criteria and corresponding action.
-
-                    A specific model name can only be matched by one rule across all
-                    rules attached to the same InferencePool. If multiple rules attempt
-                    to match the same model name, the oldest rule (by creationTimestamp)
-                    will be the only one considered valid.
+                    For details on how precedence is determined across multiple rules and
+                    InferenceModelRewrite resources, see the "Precedence and Conflict Resolution"
+                    section in InferenceModelRewriteSpec.
                   properties:
                     matches:
                       items:
@@ -110,7 +108,7 @@ spec:
                         - model
                         type: object
                       type: array
-                    split:
+                    targets:
                       items:
                         description: TargetModel defines a weighted model destination
                           for traffic distribution.

docs/proposals/1816-inferenceomodelrewrite/README.md

@@ -64,20 +64,25 @@ type InferenceModelRewriteSpec struct {
 	// If multiple InferenceModelRewrite resources target the same
 	// InferencePool, the controller will merge them based on precedence.
 	//
-	// **Timestamp Wins:** If two rules from different rewrite all matches,
-	// the rule from the *oldest*
-	// InferenceModelRewrite resource (determined by
-	// metadata.creationTimestamp) will be used.
+	// Across all rules specified on applicable rewrites, precedence MUST be
+	// given to the match having an "Exact" model match over a generic match
+	// (a rule with an empty `matches` array).
+	//
+	// If ties still exist across multiple InferenceModelRewrite resources (e.g.
+	// two rewrites both have an exact match for the same model), matching
+	// precedence MUST be determined by the oldest resource based on
+	// creation timestamp.
+	//
+	// If ties still exist within a single InferenceModelRewrite resource, the
+	// FIRST matching rule (in list order) is used.
 	// +required
 	Rules []InferenceModelRewriteRule `json:"rules"`
 }
 
 // InferenceModelRewriteRule defines the match criteria and corresponding action.
-//
-// A specific model name can only be matched by one rule across all
-// rewrites attached to the same InferencePool. If multiple rules attempt
-// to match the same model name, the oldest rule (by creationTimestamp)
-// will be the only one considered valid.
+// For details on how precedence is determined across multiple rules and
+// InferenceModelRewrite resources, see the "Precedence and Conflict Resolution"
+// section in InferenceModelRewriteSpec.
 type InferenceModelRewriteRule struct {
 	// Matches defines the criteria for matching a request.
 	// If multiple match criteria are specified, a request matches if

pkg/epp/controller/inferencemodelrewrite_reconciler.go

@@ -0,0 +1,92 @@
+/*
+Copyright 2025 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package controller
+
+import (
+	"context"
+	"fmt"
+
+	"k8s.io/apimachinery/pkg/api/errors"
+	ctrl "sigs.k8s.io/controller-runtime"
+	"sigs.k8s.io/controller-runtime/pkg/client"
+	"sigs.k8s.io/controller-runtime/pkg/event"
+	"sigs.k8s.io/controller-runtime/pkg/log"
+	"sigs.k8s.io/controller-runtime/pkg/predicate"
+
+	"sigs.k8s.io/gateway-api-inference-extension/apix/v1alpha2"
+	"sigs.k8s.io/gateway-api-inference-extension/pkg/common"
+	"sigs.k8s.io/gateway-api-inference-extension/pkg/epp/datastore"
+	logutil "sigs.k8s.io/gateway-api-inference-extension/pkg/epp/util/logging"
+)
+
+type InferenceModelRewriteReconciler struct {
+	client.Reader
+	Datastore datastore.Datastore
+	PoolGKNN  common.GKNN
+}
+
+func (c *InferenceModelRewriteReconciler) Reconcile(ctx context.Context, req ctrl.Request) (ctrl.Result, error) {
+	logger := log.FromContext(ctx).V(logutil.DEFAULT)
+	ctx = ctrl.LoggerInto(ctx, logger)
+
+	logger.Info("Reconciling InferenceModelRewrite")
+
+	infModelRewrite := &v1alpha2.InferenceModelRewrite{}
+	notFound := false
+	if err := c.Get(ctx, req.NamespacedName, infModelRewrite); err != nil {
+		if !errors.IsNotFound(err) {
+			return ctrl.Result{}, fmt.Errorf("unable to get InferenceModelRewrite - %w", err)
+		}
+		notFound = true
+	}
+
+	isDeleted := !infModelRewrite.DeletionTimestamp.IsZero()
+	isPooRefUnmatch := infModelRewrite.Spec.PoolRef == nil ||
+		infModelRewrite.Spec.PoolRef.Name != v1alpha2.ObjectName(c.PoolGKNN.Name) ||
+		infModelRewrite.Spec.PoolRef.Group != v1alpha2.Group(c.PoolGKNN.Group)
+
+	if notFound || isDeleted || isPooRefUnmatch {
+		// InferenceModelRewrite object got deleted or changed the referenced pool.
+		c.Datastore.ModelRewriteDelete(req.NamespacedName)
+		return ctrl.Result{}, nil
+	}
+
+	// Add or update if the InferenceModelRewrite instance has a creation timestamp older than the existing entry of the model.
+	logger = logger.WithValues("poolRef", infModelRewrite.Spec.PoolRef)
+	c.Datastore.ModelRewriteSet(infModelRewrite)
+	logger.Info("Added/Updated InferenceModelRewrite")
+
+	return ctrl.Result{}, nil
+}
+
+func (c *InferenceModelRewriteReconciler) SetupWithManager(ctx context.Context, mgr ctrl.Manager) error {
+	return ctrl.NewControllerManagedBy(mgr).
+		For(&v1alpha2.InferenceModelRewrite{}).
+		WithEventFilter(predicate.Funcs{
+			CreateFunc: func(e event.CreateEvent) bool { return c.eventPredicate(e.Object.(*v1alpha2.InferenceModelRewrite)) },
+			UpdateFunc: func(e event.UpdateEvent) bool {
+				return c.eventPredicate(e.ObjectOld.(*v1alpha2.InferenceModelRewrite)) || c.eventPredicate(e.ObjectNew.(*v1alpha2.InferenceModelRewrite))
+			},
+			DeleteFunc:  func(e event.DeleteEvent) bool { return c.eventPredicate(e.Object.(*v1alpha2.InferenceModelRewrite)) },
+			GenericFunc: func(e event.GenericEvent) bool { return c.eventPredicate(e.Object.(*v1alpha2.InferenceModelRewrite)) },
+		}).
+		Complete(c)
+}
+
+func (c *InferenceModelRewriteReconciler) eventPredicate(infModelRewrite *v1alpha2.InferenceModelRewrite) bool {
+	return infModelRewrite.Spec.PoolRef != nil && string(infModelRewrite.Spec.PoolRef.Name) == c.PoolGKNN.Name && string(infModelRewrite.Spec.PoolRef.Group) == c.PoolGKNN.Group
+}