Track runner spec updates with an actionable revision (#4638)

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>
2026-10-19 04:18:23 +02:00 · 2026-09-11 12:44:03 +00:00
parent 5581cd0c54
commit 6f89d057c0
14 changed files with 1010 additions and 40 deletions
@@ -1,9 +1,112 @@
 package actionsgithubcom

 import (
+	"fmt"
 	"testing"
+
+	"github.com/actions/actions-runner-controller/apis/actions.github.com/v1alpha1"
+	corev1 "k8s.io/api/core/v1"
+	"k8s.io/apimachinery/pkg/api/resource"
 )

+// benchmarkEphemeralRunnerSet builds a runner set roughly the size of a real
+// ARC deployment: a runner container, a dind sidecar, an init container,
+// resource limits, volumes and a dozen environment variables.
+func benchmarkEphemeralRunnerSet() *v1alpha1.EphemeralRunnerSet {
+	env := make([]corev1.EnvVar, 0, 12)
+	for i := range 12 {
+		env = append(env, corev1.EnvVar{Name: fmt.Sprintf("VAR_%d", i), Value: fmt.Sprintf("value-%d", i)})
+	}
+	q := resource.MustParse
+
+	return &v1alpha1.EphemeralRunnerSet{
+		Spec: v1alpha1.EphemeralRunnerSetSpec{
+			Replicas: 10,
+			PatchID:  7,
+			EphemeralRunnerSpec: v1alpha1.EphemeralRunnerSpec{
+				GitHubConfigURL:    "https://github.com/octo-org",
+				GitHubConfigSecret: "gh-config",
+				RunnerScaleSetID:   42,
+				PodTemplateSpec: corev1.PodTemplateSpec{
+					Spec: corev1.PodSpec{
+						ServiceAccountName: "runner-sa",
+						RestartPolicy:      corev1.RestartPolicyNever,
+						NodeSelector:       map[string]string{"kubernetes.io/os": "linux", "node.kubernetes.io/pool": "runners"},
+						Tolerations: []corev1.Toleration{{
+							Key: "dedicated", Operator: corev1.TolerationOpEqual,
+							Value: "runners", Effect: corev1.TaintEffectNoSchedule,
+						}},
+						Volumes: []corev1.Volume{
+							{Name: "work", VolumeSource: corev1.VolumeSource{EmptyDir: &corev1.EmptyDirVolumeSource{}}},
+							{Name: "dind-sock", VolumeSource: corev1.VolumeSource{EmptyDir: &corev1.EmptyDirVolumeSource{}}},
+						},
+						InitContainers: []corev1.Container{{
+							Name: "init-dind", Image: "docker:dind",
+							Command:      []string{"cp"},
+							Args:         []string{"-r", "/usr/local/bin/.", "/dind"},
+							VolumeMounts: []corev1.VolumeMount{{Name: "dind-sock", MountPath: "/dind"}},
+						}},
+						Containers: []corev1.Container{
+							{
+								Name:    "runner",
+								Image:   "ghcr.io/actions/actions-runner:2.337.0",
+								Command: []string{"/home/runner/run.sh"},
+								Env:     env,
+								VolumeMounts: []corev1.VolumeMount{
+									{Name: "work", MountPath: "/home/runner/_work"},
+									{Name: "dind-sock", MountPath: "/var/run"},
+								},
+								Resources: corev1.ResourceRequirements{
+									Requests: corev1.ResourceList{corev1.ResourceCPU: q("500m"), corev1.ResourceMemory: q("1Gi")},
+									Limits:   corev1.ResourceList{corev1.ResourceCPU: q("2"), corev1.ResourceMemory: q("4Gi")},
+								},
+							},
+							{
+								Name: "dind", Image: "docker:dind", Env: env[:6],
+								VolumeMounts: []corev1.VolumeMount{{Name: "dind-sock", MountPath: "/var/run"}},
+							},
+						},
+					},
+				},
+			},
+		},
+	}
+}
+
+// BenchmarkEphemeralRunnerSetActionableSpecChanged measures the drift check that
+// runs on every AutoscalingRunnerSet reconcile. Reconciles are driven by
+// EphemeralRunnerSet status churn via Owns(), so this executes constantly and
+// its allocation count feeds directly into controller GC pressure.
+//
+// For reference on the machine this was written on: Semantic.DeepEqual is around
+// 65us/241 allocs, versus 332us/405 allocs for cmp.Equal. If this regresses by an
+// order of magnitude, something switched the comparison back to a reflection
+// heavy implementation.
+func BenchmarkEphemeralRunnerSetActionableSpecChanged(b *testing.B) {
+	b.Run("no drift", func(b *testing.B) {
+		current, desired := benchmarkEphemeralRunnerSet(), benchmarkEphemeralRunnerSet()
+		b.ReportAllocs()
+		b.ResetTimer()
+		for range b.N {
+			if ephemeralRunnerSetActionableSpecChanged(current, desired) {
+				b.Fatal("expected no drift")
+			}
+		}
+	})
+
+	b.Run("drift", func(b *testing.B) {
+		current, desired := benchmarkEphemeralRunnerSet(), benchmarkEphemeralRunnerSet()
+		desired.Spec.EphemeralRunnerSpec.PodTemplateSpec.Spec.Containers[0].Image = "ghcr.io/actions/actions-runner:2.338.0"
+		b.ReportAllocs()
+		b.ResetTimer()
+		for range b.N {
+			if !ephemeralRunnerSetActionableSpecChanged(current, desired) {
+				b.Fatal("expected drift")
+			}
+		}
+	})
+}
+
 // BenchmarkListenerPodSpecRequiresRecreation measures the listener pod drift
 // check, which also runs on every AutoscalingListener reconcile.
 func BenchmarkListenerPodSpecRequiresRecreation(b *testing.B) {