feat(k8s): add stability check for HPA (#4363)

Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>

clouddriver-kubernetes-v2/src/main/java/com/netflix/spinnaker/clouddriver/kubernetes/v2/op/handler/KubernetesHorizontalPodAutoscalerHandler.java

@@ -22,12 +22,16 @@
 import com.google.common.collect.ImmutableList;
 import com.netflix.spinnaker.clouddriver.kubernetes.description.SpinnakerKind;
 import com.netflix.spinnaker.clouddriver.kubernetes.v2.artifact.Replacer;
+import com.netflix.spinnaker.clouddriver.kubernetes.v2.caching.agent.KubernetesCacheDataConverter;
 import com.netflix.spinnaker.clouddriver.kubernetes.v2.caching.agent.KubernetesCoreCachingAgent;
 import com.netflix.spinnaker.clouddriver.kubernetes.v2.caching.agent.KubernetesV2CachingAgentFactory;
 import com.netflix.spinnaker.clouddriver.kubernetes.v2.description.manifest.KubernetesKind;
 import com.netflix.spinnaker.clouddriver.kubernetes.v2.description.manifest.KubernetesManifest;
 import com.netflix.spinnaker.clouddriver.kubernetes.v2.model.Manifest.Status;
+import io.kubernetes.client.openapi.models.V1HorizontalPodAutoscaler;
+import io.kubernetes.client.openapi.models.V1HorizontalPodAutoscalerStatus;
 import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
 import org.springframework.stereotype.Component;
 
 @Component
@@ -62,9 +66,43 @@ public SpinnakerKind spinnakerKind() {
 
   @Override
   public Status status(KubernetesManifest manifest) {
+    V1HorizontalPodAutoscaler hpa =
+        KubernetesCacheDataConverter.getResource(manifest, V1HorizontalPodAutoscaler.class);
+    return status(hpa);
+  }
+
+  private Status status(V1HorizontalPodAutoscaler hpa) {
+    V1HorizontalPodAutoscalerStatus status = hpa.getStatus();
+    if (status == null) {
+      return Status.noneReported();
+    }
+
+    int desiredReplicas = defaultToZero(status.getDesiredReplicas());
+    int existing = defaultToZero(status.getCurrentReplicas());
+    if (desiredReplicas > existing) {
+      return Status.defaultStatus()
+          .unstable(
+              String.format(
+                  "Waiting for HPA to complete a scale up, current: %d desired: %d",
+                  existing, desiredReplicas));
+    }
+
+    if (desiredReplicas < existing) {
+      return Status.defaultStatus()
+          .unstable(
+              String.format(
+                  "Waiting for HPA to complete a scale down, current: %d desired: %d",
+                  existing, desiredReplicas));
+    }
+    // desiredReplicas == existing, this is now stable
     return Status.defaultStatus();
   }
 
+  // Unboxes an Integer, returning 0 if the input is null
+  private static int defaultToZero(@Nullable Integer input) {
+    return input == null ? 0 : input;
+  }
+
   @Override
   protected KubernetesV2CachingAgentFactory cachingAgentFactory() {
     return KubernetesCoreCachingAgent::new;

clouddriver-kubernetes-v2/src/test/java/com/netflix/spinnaker/clouddriver/kubernetes/v2/op/handler/KubernetesHorizontalPodAutoscalerTest.java

@@ -0,0 +1,100 @@
+/*
+ * Copyright 2020 Snap Inc
+ *
+ * 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 com.netflix.spinnaker.clouddriver.kubernetes.v2.op.handler;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import com.netflix.spinnaker.clouddriver.kubernetes.v2.description.manifest.KubernetesManifest;
+import com.netflix.spinnaker.clouddriver.kubernetes.v2.model.Manifest.Status;
+import org.junit.jupiter.api.Test;
+import org.junit.platform.runner.JUnitPlatform;
+import org.junit.runner.RunWith;
+
+@RunWith(JUnitPlatform.class)
+final class KubernetesHorizontalPodAutoscalerHandlerTest {
+  private KubernetesHorizontalPodAutoscalerHandler handler =
+      new KubernetesHorizontalPodAutoscalerHandler();
+
+  @Test
+  void noStatus() {
+    KubernetesManifest hpa = ManifestFetcher.getManifest("horizontalpodautoscaler/base.yml");
+    Status status = handler.status(hpa);
+
+    assertThat(status.getStable().isState()).isFalse();
+    assertThat(status.getStable().getMessage()).isEqualTo("No status reported yet");
+    assertThat(status.getAvailable().isState()).isFalse();
+    assertThat(status.getPaused().isState()).isFalse();
+    assertThat(status.getFailed().isState()).isFalse();
+  }
+
+  @Test
+  void waitingForScaleup() {
+    KubernetesManifest hpa =
+        ManifestFetcher.getManifest(
+            "horizontalpodautoscaler/base.yml", "horizontalpodautoscaler/waiting-for-scaleup.yml");
+    Status status = handler.status(hpa);
+
+    assertThat(status.getStable().isState()).isFalse();
+    assertThat(status.getStable().getMessage())
+        .isEqualTo("Waiting for HPA to complete a scale up, current: 2 desired: 3");
+    assertThat(status.getAvailable().isState()).isTrue();
+    assertThat(status.getPaused().isState()).isFalse();
+    assertThat(status.getFailed().isState()).isFalse();
+  }
+
+  @Test
+  void waitingForScaledown() {
+    KubernetesManifest hpa =
+        ManifestFetcher.getManifest(
+            "horizontalpodautoscaler/base.yml",
+            "horizontalpodautoscaler/waiting-for-scaledown.yml");
+    Status status = handler.status(hpa);
+
+    assertThat(status.getStable().isState()).isFalse();
+    assertThat(status.getStable().getMessage())
+        .isEqualTo("Waiting for HPA to complete a scale down, current: 5 desired: 2");
+    assertThat(status.getAvailable().isState()).isTrue();
+    assertThat(status.getPaused().isState()).isFalse();
+    assertThat(status.getFailed().isState()).isFalse();
+  }
+
+  @Test
+  void noReplicas() {
+    KubernetesManifest hpa =
+        ManifestFetcher.getManifest(
+            "horizontalpodautoscaler/base.yml", "horizontalpodautoscaler/no-replicas.yml");
+    Status status = handler.status(hpa);
+
+    assertThat(status.getStable().isState()).isTrue();
+    assertThat(status.getAvailable().isState()).isTrue();
+    assertThat(status.getPaused().isState()).isFalse();
+    assertThat(status.getFailed().isState()).isFalse();
+  }
+
+  @Test
+  void stable() {
+    KubernetesManifest hpa =
+        ManifestFetcher.getManifest(
+            "horizontalpodautoscaler/base.yml", "horizontalpodautoscaler/stable.yml");
+    Status status = handler.status(hpa);
+
+    assertThat(status.getStable().isState()).isTrue();
+    assertThat(status.getAvailable().isState()).isTrue();
+    assertThat(status.getPaused().isState()).isFalse();
+    assertThat(status.getFailed().isState()).isFalse();
+  }
+}

clouddriver-kubernetes-v2/src/test/resources/com/netflix/spinnaker/clouddriver/kubernetes/v2/op/handler/horizontalpodautoscaler/base.yml

@@ -0,0 +1,20 @@
+apiVersion: autoscaling/v1
+kind: HorizontalPodAutoscaler
+metadata:
+  annotations: {}
+  creationTimestamp: '2020-02-10T21:45:07Z'
+  labels: {}
+  name: test-hpa
+  namespace: default
+  resourceVersion: '169474131'
+  selfLink: >-
+    /apis/autoscaling/v1/namespaces/default/horizontalpodautoscalers/test-hpa
+  uid: 00000000-0000-0000-0000-000000000000
+spec:
+  maxReplicas: 5
+  minReplicas: 2
+  scaleTargetRef:
+    apiVersion: extensions/v1beta1
+    kind: Deployment
+    name: test-deployment
+  targetCPUUtilizationPercentage: 40

clouddriver-kubernetes-v2/src/test/resources/com/netflix/spinnaker/clouddriver/kubernetes/v2/op/handler/horizontalpodautoscaler/no-replicas.yml

@@ -0,0 +1,4 @@
+status:
+  currentReplicas: 0
+  desiredReplicas: 0
+  lastScaleTime: '2020-02-25T20:32:16Z'

clouddriver-kubernetes-v2/src/test/resources/com/netflix/spinnaker/clouddriver/kubernetes/v2/op/handler/horizontalpodautoscaler/stable.yml

@@ -0,0 +1,4 @@
+status:
+  currentReplicas: 2
+  desiredReplicas: 2
+  lastScaleTime: '2020-02-25T20:32:16Z'

clouddriver-kubernetes-v2/src/test/resources/com/netflix/spinnaker/clouddriver/kubernetes/v2/op/handler/horizontalpodautoscaler/waiting-for-scaledown.yml

@@ -0,0 +1,4 @@
+status:
+  currentReplicas: 5
+  desiredReplicas: 2
+  lastScaleTime: '2020-02-25T20:32:16Z'

clouddriver-kubernetes-v2/src/test/resources/com/netflix/spinnaker/clouddriver/kubernetes/v2/op/handler/horizontalpodautoscaler/waiting-for-scaleup.yml

@@ -0,0 +1,4 @@
+status:
+  currentReplicas: 2
+  desiredReplicas: 3
+  lastScaleTime: '2020-02-25T20:32:16Z'