nrt: filter: log correctly sidecar containers

add utilities to recognize sidecar containers,
and log them correctly.

Signed-off-by: Francesco Romani <[email protected]>

Author: ffromani

pkg/noderesourcetopology/filter.go

@@ -55,15 +55,16 @@ func singleNUMAContainerLevelHandler(lh logr.Logger, pod *v1.Pod, zones topology
 	// https://kubernetes.io/docs/concepts/workloads/pods/init-containers/#understanding-init-containers
 	// therefore, we don't need to accumulate their resources together
 	for _, initContainer := range pod.Spec.InitContainers {
-		// TODO: handle sidecar explicitely (new kind)
-		clh := lh.WithValues(logging.KeyContainer, initContainer.Name, logging.KeyContainerKind, logging.KindContainerInit)
+		cntKind := logging.GetInitContainerKind(&initContainer)
+		clh := lh.WithValues(logging.KeyContainer, initContainer.Name, logging.KeyContainerKind, cntKind)
 		clh.V(6).Info("desired resources", stringify.ResourceListToLoggable(initContainer.Resources.Requests)...)
 
 		_, match := resourcesAvailableInAnyNUMANodes(clh, nodes, initContainer.Resources.Requests, qos, nodeInfo)
 		if !match {
+			msg := "cannot align " + cntKind + " container"
 			// we can't align init container, so definitely we can't align a pod
-			clh.V(2).Info("cannot align container")
-			return framework.NewStatus(framework.Unschedulable, "cannot align init container")
+			clh.V(2).Info(msg)
+			return framework.NewStatus(framework.Unschedulable, msg)
 		}
 	}
 

pkg/noderesourcetopology/logging/logging.go

@@ -20,6 +20,7 @@ import (
 	"reflect"
 
 	corev1 "k8s.io/api/core/v1"
+	"sigs.k8s.io/scheduler-plugins/pkg/util"
 )
 
 // well-known structured log keys
@@ -44,8 +45,9 @@ const (
 )
 
 const (
-	KindContainerInit string = "init"
-	KindContainerApp  string = "app"
+	KindContainerInit    string = "init"
+	KindContainerSidecar string = "sidecar"
+	KindContainerApp     string = "app"
 )
 
 const (
@@ -62,3 +64,10 @@ func PodUID(pod *corev1.Pod) string {
 	}
 	return string(pod.GetUID())
 }
+
+func GetInitContainerKind(container *corev1.Container) string {
+	if util.IsSidecarInitContainer(container) {
+		return KindContainerSidecar
+	}
+	return KindContainerInit
+}

pkg/util/sidecar.go

@@ -0,0 +1,27 @@
+/*
+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 util
+
+import (
+	v1 "k8s.io/api/core/v1"
+)
+
+// IsSidecarInitContainer assumes the given container is a pod init container;
+// returns true if that container is a sidecar, false otherwise.
+func IsSidecarInitContainer(container *v1.Container) bool {
+	return container.RestartPolicy != nil && *container.RestartPolicy == v1.ContainerRestartPolicyAlways
+}

pkg/util/sidecar_test.go

@@ -0,0 +1,61 @@
+/*
+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 util
+
+import (
+	"testing"
+
+	v1 "k8s.io/api/core/v1"
+)
+
+func TestIsSidecarInitContainer(t *testing.T) {
+	always_ := v1.ContainerRestartPolicyAlways
+	testCases := []struct {
+		name     string
+		cnt      *v1.Container
+		expected bool
+	}{
+		{
+			name:     "zero value",
+			cnt:      &v1.Container{},
+			expected: false,
+		},
+		{
+			name: "explicit nil",
+			cnt: &v1.Container{
+				RestartPolicy: nil,
+			},
+			expected: false,
+		},
+		{
+			name: "true sidecar container",
+			cnt: &v1.Container{
+				Name:          "init-1",
+				RestartPolicy: &always_,
+			},
+			expected: true,
+		},
+	}
+	for _, testCase := range testCases {
+		t.Run(string(testCase.name), func(t *testing.T) {
+			got := IsSidecarInitContainer(testCase.cnt)
+			if got != testCase.expected {
+				t.Fatalf("expected %t to equal %t", got, testCase.expected)
+			}
+		})
+	}
+}