test: Scale up and down the model server during an end to end test (llm-d#354)

* Added a helper to scale up/down deployments

Signed-off-by: Shmuel Kallner <kallner@il.ibm.com>

* Added a test in which the model server is scaled up and down

Signed-off-by: Shmuel Kallner <kallner@il.ibm.com>

* Fixed typo

Signed-off-by: Shmuel Kallner <kallner@il.ibm.com>

* Fixed lint issue

Signed-off-by: Shmuel Kallner <kallner@il.ibm.com>

* Restored code commented out for debugging

Signed-off-by: Shmuel Kallner <kallner@il.ibm.com>

* Updates due to review comments

Signed-off-by: Shmuel Kallner <kallner@il.ibm.com>

* Added comments for clarification

Signed-off-by: Shmuel Kallner <kallner@il.ibm.com>

* Changes due to refactoring done in prior PRs

Signed-off-by: Shmuel Kallner <kallner@il.ibm.com>

---------

Signed-off-by: Shmuel Kallner <kallner@il.ibm.com>

Author: shmuelk

test/e2e/e2e_test.go

@@ -129,6 +129,60 @@ var _ = ginkgo.Describe("Run end to end tests", ginkgo.Ordered, func() {
 			testutils.DeleteObjects(testConfig, modelServers)
 		})
 	})
+
+	ginkgo.When("Scaling up and down the model servers", func() {
+		ginkgo.It("should distribute inference requests across all model servers", func() {
+			modelServers := createModelServers(false, false, 1, 0, 0)
+
+			epp := createEndPointPicker(scaleConfig)
+
+			prefillPods, decodePods := getModelServerPods(podSelector, prefillSelector, decodeSelector)
+			gomega.Expect(prefillPods).Should(gomega.BeEmpty())
+			gomega.Expect(decodePods).Should(gomega.HaveLen(1))
+
+			var nsHdr, podHdr string
+			for range 5 {
+				nsHdr, podHdr = runCompletion(simplePrompt, modelName)
+				gomega.Expect(nsHdr).Should(gomega.Equal(nsName))
+				gomega.Expect(podHdr).Should(gomega.Equal(decodePods[0]))
+			}
+
+			scaleDeployment(modelServers, 1)
+
+			scaledUpPrefillPods, scaledUpDecodePods := getModelServerPods(podSelector, prefillSelector, decodeSelector)
+			gomega.Expect(scaledUpPrefillPods).Should(gomega.BeEmpty())
+			gomega.Expect(scaledUpDecodePods).Should(gomega.HaveLen(2))
+
+			var scaledNsHdr, scaledPodHdr string
+			// Run inference multiple times until one is scheduled on the new pod
+			for range 30 {
+				scaledNsHdr, scaledPodHdr = runCompletion(extraPrompt, modelName)
+				gomega.Expect(scaledNsHdr).Should(gomega.Equal(nsName))
+				gomega.Expect(scaledPodHdr).Should(gomega.BeElementOf(scaledUpDecodePods))
+				if scaledPodHdr != podHdr {
+					break
+				}
+			}
+			gomega.Expect(scaledPodHdr).ShouldNot(gomega.Equal(podHdr))
+
+			scaleDeployment(modelServers, -1)
+
+			scaledDownPrefillPods, scaledDownDecodePods := getModelServerPods(podSelector, prefillSelector, decodeSelector)
+			gomega.Expect(scaledDownPrefillPods).Should(gomega.BeEmpty())
+			gomega.Expect(scaledDownDecodePods).Should(gomega.HaveLen(1))
+			gomega.Expect(scaledDownDecodePods[0]).Should(gomega.BeElementOf(scaledUpDecodePods))
+
+			// Run multiple times and insure that they are scheduled on the remaining pod
+			for range 5 {
+				nsHdr, podHdr = runCompletion(simplePrompt, modelName)
+				gomega.Expect(nsHdr).Should(gomega.Equal(nsName))
+				gomega.Expect(podHdr).Should(gomega.Equal(scaledDownDecodePods[0]))
+			}
+
+			testutils.DeleteObjects(testConfig, epp)
+			testutils.DeleteObjects(testConfig, modelServers)
+		})
+	})
 })
 
 // createModelServers creates the model server resources used for testing from the given filePaths.
@@ -341,3 +395,15 @@ schedulingProfiles:
   - pluginRef: precise-prefix-cache-scorer
     weight: 10
 `
+
+// EPP configuration for running scale model server test
+const scaleConfig = `apiVersion: inference.networking.x-k8s.io/v1alpha1
+kind: EndpointPickerConfig
+plugins:
+- type: max-score-picker
+- type: single-profile-handler
+schedulingProfiles:
+- name: default
+  plugins:
+  - pluginRef: max-score-picker
+`

test/e2e/utils_test.go

@@ -11,11 +11,44 @@ import (
 	"github.com/onsi/gomega/gexec"
 	appsv1 "k8s.io/api/apps/v1"
 	corev1 "k8s.io/api/core/v1"
+	v1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	apilabels "k8s.io/apimachinery/pkg/labels"
 	"k8s.io/apimachinery/pkg/types"
+	"k8s.io/client-go/kubernetes"
 	"sigs.k8s.io/controller-runtime/pkg/client"
+	"sigs.k8s.io/controller-runtime/pkg/client/config"
 )
 
+const (
+	deploymentKind = "deployment"
+)
+
+func scaleDeployment(objects []string, increment int) {
+	k8sCfg := config.GetConfigOrDie()
+	client, err := kubernetes.NewForConfig(k8sCfg)
+	gomega.Expect(err).NotTo(gomega.HaveOccurred())
+	direction := "up"
+	absIncrement := increment
+	if increment < 0 {
+		direction = "down"
+		absIncrement = -increment
+	}
+
+	for _, kindAndName := range objects {
+		split := strings.Split(kindAndName, "/")
+		if strings.ToLower(split[0]) == deploymentKind {
+			ginkgo.By(fmt.Sprintf("Scaling the deployment %s %s by %d", split[1], direction, absIncrement))
+			scale, err := client.AppsV1().Deployments(nsName).GetScale(testConfig.Context, split[1], v1.GetOptions{})
+			gomega.Expect(err).NotTo(gomega.HaveOccurred())
+
+			scale.Spec.Replicas += int32(increment)
+			_, err = client.AppsV1().Deployments(nsName).UpdateScale(testConfig.Context, split[1], scale, v1.UpdateOptions{})
+			gomega.Expect(err).NotTo(gomega.HaveOccurred())
+		}
+	}
+	podsInDeploymentsReady(objects)
+}
+
 // getModelServerPods Returns the list of Prefill and Decode vLLM pods separately
 func getModelServerPods(podLabels, prefillLabels, decodeLabels map[string]string) ([]string, []string) {
 	pods := getPods(podLabels)
@@ -73,11 +106,12 @@ func podsInDeploymentsReady(objects []string) {
 	var deployment appsv1.Deployment
 	helper := func(deploymentName string) bool {
 		err := testConfig.K8sClient.Get(testConfig.Context, types.NamespacedName{Namespace: nsName, Name: deploymentName}, &deployment)
-		return err == nil && deployment.Status.Replicas == deployment.Status.ReadyReplicas
+		return err == nil && *deployment.Spec.Replicas == deployment.Status.Replicas &&
+			deployment.Status.Replicas == deployment.Status.ReadyReplicas
 	}
 	for _, kindAndName := range objects {
 		split := strings.Split(kindAndName, "/")
-		if strings.ToLower(split[0]) == "deployment" {
+		if strings.ToLower(split[0]) == deploymentKind {
 			ginkgo.By(fmt.Sprintf("Waiting for pods of %s to be ready", split[1]))
 			gomega.Eventually(helper, readyTimeout, interval).WithArguments(split[1]).Should(gomega.BeTrue())
 		}