From 7504d509affa64934220a25307cc14d27cbda7c4 Mon Sep 17 00:00:00 2001
From: Etienne Perot <eperot@google.com>
Date: Wed, 6 May 2026 16:31:22 -0700
Subject: [PATCH] Add explicit resource limits for Kata containers in
 Kubernetes tests.

Kata containers require explicit resource limits to function correctly,
otherwise they get the default size which is too small to fit most workloads.

PiperOrigin-RevId: 911613991
---
 test/kubernetes/testcluster/objects.go     |  7 ++++
 test/kubernetes/testcluster/testcluster.go | 40 ++++++++++++++++++++++
 2 files changed, 47 insertions(+)

diff --git a/test/kubernetes/testcluster/objects.go b/test/kubernetes/testcluster/objects.go
index 384a5d5fed..bef7569fda 100644
--- a/test/kubernetes/testcluster/objects.go
+++ b/test/kubernetes/testcluster/objects.go
@@ -408,6 +408,13 @@ func (t RuntimeType) KataShimName() (string, error) {
 	}
 }
 
+// RequiresExplicitResourceLimits returns true if the runtime requires
+// explicit resource limits on pods in order to function correctly.
+func (t RuntimeType) RequiresExplicitResourceLimits() bool {
+	// Kata containers requires VMs which require explicit sizing.
+	return t.IsKata()
+}
+
 // ApplyNodepool modifies the nodepool to configure it to use the runtime.
 func (t RuntimeType) ApplyNodepool(nodepool *cspb.NodePool) {
 	if nodepool.GetConfig().GetLabels() == nil {
diff --git a/test/kubernetes/testcluster/testcluster.go b/test/kubernetes/testcluster/testcluster.go
index 6c31690aef..3927380934 100644
--- a/test/kubernetes/testcluster/testcluster.go
+++ b/test/kubernetes/testcluster/testcluster.go
@@ -712,6 +712,46 @@ func (t *TestCluster) applyCommonPodConfigurations(ctx context.Context, np *Node
 	}
 	// Apply the runtime we've chosen, whether by override or autodetection.
 	applyRuntime.ApplyPodSpec(podSpec)
+	if applyRuntime.RequiresExplicitResourceLimits() {
+		const (
+			overheadMargin = 0.2
+			leftoverRatio  = 1.0 - overheadMargin
+		)
+		cores := int(float64(np.spec.NumCores) * leftoverRatio)
+		if cores < 1 {
+			cores = 1
+		}
+		memMiB := int(float64(np.spec.MemoryGiB) * 1024 * leftoverRatio)
+		resCPU := resource.MustParse(fmt.Sprintf("%d", cores))
+		resMem := resource.MustParse(fmt.Sprintf("%dMi", memMiB))
+		for _, containers := range [][]v13.Container{
+			podSpec.InitContainers,
+			podSpec.Containers,
+		} {
+			for i := range containers {
+				if containers[i].Resources.Limits == nil {
+					containers[i].Resources.Limits = make(v13.ResourceList)
+				}
+				if containers[i].Resources.Requests == nil {
+					containers[i].Resources.Requests = make(v13.ResourceList)
+				}
+				for _, res := range []struct {
+					key v13.ResourceName
+					val resource.Quantity
+				}{
+					{v13.ResourceCPU, resCPU},
+					{v13.ResourceMemory, resMem},
+				} {
+					if _, ok := containers[i].Resources.Requests[res.key]; !ok {
+						containers[i].Resources.Requests[res.key] = res.val
+					}
+					if _, ok := containers[i].Resources.Limits[res.key]; !ok {
+						containers[i].Resources.Limits[res.key] = res.val
+					}
+				}
+			}
+		}
+	}
 
 	// If the nodepool has accelerators, copy the number of them as a node
 	// selector option.