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Workaround for HPA dry-run metrics duplication #207

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merged 1 commit into from
Jan 6, 2022
Merged

Workaround for HPA dry-run metrics duplication #207

merged 1 commit into from
Jan 6, 2022

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stefanprodan
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@stefanprodan stefanprodan commented Jan 5, 2022 •
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This PR implements a workaround for a Kubernetes API server-side apply dry-run bug where it duplicates the first item in the metrics array and inserts an empty metric as the last item in the array.

Given:

apiVersion: autoscaling/v2beta2
kind: HorizontalPodAutoscaler
metadata:
  name: frontend
  namespace: default
spec:
  behavior:
    scaleDown:
      policies:
        - periodSeconds: 15
          type: Percent
          value: 100
      selectPolicy: Max
      stabilizationWindowSeconds: 60
    scaleUp:
      policies:
        - periodSeconds: 15
          type: Pods
          value: 4
        - periodSeconds: 15
          type: Percent
          value: 100
      selectPolicy: Max
      stabilizationWindowSeconds: 0
  maxReplicas: 30
  metrics:
    - type: Pods
      pods:
        metric:
          name: nginx_http_requests_total
        target:
          averageValue: "4"
          type: AverageValue
  minReplicas: 2
  scaleTargetRef:
    apiVersion: apps/v1
    kind: Deployment
    name: frontend

The dry-run diff returns bogus data:

$ kubectl diff --server-side -f hpa.yaml
@@ -74,6 +97,13 @@
         averageValue: "4"
         type: AverageValue
     type: Pods
+  - pods:
+      metric:
+        name: nginx_http_requests_total
+      target:
+        averageValue: "4"
+        type: AverageValue
+    type: Pods

This gets even worse if you have two metrics, now an empty metric is added by the Kubernetes API:

$ kubectl diff --server-side -f hpa.yaml
+  - pods:
+      metric:
+        name: nginx_http_requests_total
+      target:
+        averageValue: "4"
+        type: AverageValue
+    type: Pods
+  - type: ""

Ref: fluxcd/kustomize-controller#494

@stefanprodan stefanprodan added the area/server-side-apply SSA related issues and pull requests label Jan 5, 2022
@stefanprodan stefanprodan force-pushed the ssa-hpa-diff branch 4 times, most recently from dbebbc8 to 1db33d7 Compare January 5, 2022 23:11
darkowlzz
darkowlzz approved these changes Jan 6, 2022
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LGTM!
Thanks.

@stefanprodan stefanprodan merged commit 1609286 into main Jan 6, 2022
@stefanprodan stefanprodan deleted the ssa-hpa-diff branch January 6, 2022 08:40
This was referenced Jan 6, 2022
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@hiddeco hiddeco mentioned this pull request Dec 15, 2022
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@somtochiama somtochiama mentioned this pull request Jan 11, 2023
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@stefanprodan @darkowlzz