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Mark webhook and controller as safe-to-evict #4124

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Jul 29, 2021
Merged

Mark webhook and controller as safe-to-evict #4124

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2 changes: 0 additions & 2 deletions config/controller.yaml
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Original file line number Diff line number Diff line change
Expand Up @@ -37,8 +37,6 @@ spec:
app.kubernetes.io/part-of: tekton-pipelines
template:
metadata:
annotations:
cluster-autoscaler.kubernetes.io/safe-to-evict: "false"
labels:
app.kubernetes.io/name: controller
app.kubernetes.io/component: controller
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2 changes: 0 additions & 2 deletions config/webhook.yaml
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Expand Up @@ -40,8 +40,6 @@ spec:
app.kubernetes.io/part-of: tekton-pipelines
template:
metadata:
annotations:
cluster-autoscaler.kubernetes.io/safe-to-evict: "false"
labels:
app.kubernetes.io/name: webhook
app.kubernetes.io/component: webhook
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6 changes: 3 additions & 3 deletions docs/enabling-ha.md
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Expand Up @@ -95,9 +95,9 @@ spec:
minReplicas: 1
```

By default, the Webhook deployment is configured to block a [Cluster Autoscaler](https://github.com/kubernetes/autoscaler/tree/master/cluster-autoscaler) from scaling down the node that's running the only replica of the deployment using the `cluster-autoscaler.kubernetes.io/safe-to-evict` annotation.
This is configured because, while the only replica of the Webhook is unavailable, Tekton resources can't be created, updated or deleted.
If you configure more than one replica, you can remove the annotation to allow the Cluster Autoscaler more freedom to scale down nodes, without disrupting the Webhook service.
By default, the Webhook deployment is _not_ configured to block a [Cluster Autoscaler](https://github.com/kubernetes/autoscaler/tree/master/cluster-autoscaler) from scaling down the node that's running the only replica of the deployment using the `cluster-autoscaler.kubernetes.io/safe-to-evict` annotation.
This means that during node drains, the Webhook might be unavailable temporarily, during which time Tekton resources can't be created, updated or deleted.
To avoid this, you can add the `safe-to-evict` annotation set to `false` to block node drains during autoscaling, or, better yet, configure multiple replicas of the Webhook deployment.

### Avoiding Disruptions

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