Cluster scaling (#2370)

Co-authored-by: Jose Armesto <[email protected]>

src/content/tutorials/fleet-management/cluster-management/cluster-autoscaler/index.md

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+---
+linkTitle: Cluster autoscaler
+title: Advanced cluster autoscaler configuration
+description: Here we describe how you can customize the configuration of the managed cluster autoscaler service in your workload clusters.
+weight: 90
+menu:
+  principal:
+    parent: tutorials-fleet-management-clusters
+    identifier: tutorials-fleet-management-clusters-cluster-autoscaler
+user_questions:
+  - Where can I find the ConfigMap to configure cluster-autoscaler?
+  - What cluster-autoscaler options can I configure?
+last_review_date: 2024-12-13
+owner:
+  - https://github.com/orgs/giantswarm/teams/team-phoenix
+---
+
+In Giant Swarm platform, your workload clusters come with default autoscaling functionality. Today, it's supported by {{/*% autoscaling_supported_versions*/%}}, but our goal is to bring this feature to all supported providers.
+
+The cluster autoscaler runs in the workload cluster and is responsible for scaling the number of nodes in the cluster. The configuration though is managed in the management cluster though. The autoscaling controller has a default configuration for the [cluster-autoscaler addon](https://github.com/kubernetes/autoscaler/tree/master/cluster-autoscaler). To configure the `cluster-autoscaler` further, you need to access the platform API. [Learn how to access the platform API]({{< relref "/getting-started/access-to-platform-api" >}}).
+
+To extend the configuration, you need to override these defaults using a `ConfigMap` with the convention name `cluster-autoscaler-user-values`.
+
+## Where is the user values ConfigMap
+
+The following examples assume the cluster you are trying to configure has an id of `myclustername`.
+
+You will find the `ConfigMap` named `myclustername-cluster-autoscaler-user-values` in the organization namespace of your cluster:
+
+```text
+$ kubectl -n org-company get cm myclustername-cluster-autoscaler-user-values
+NAME                                       DATA      AGE
+myclustername-cluster-autoscaler-user-values         0         11m
+```
+
+## How to set configuration options using the user values ConfigMap
+
+On the platform API, create or edit a ConfigMap named `myclustername-cluster-autoscaler-user-values`
+in the workload cluster namespace:
+
+```yaml
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  labels:
+    app: cluster-autoscaler
+  name: myclustername-cluster-autoscaler-user-values
+  namespace: myorg
+data:
+  values: |
+    configmap:
+      scaleDownUtilizationThreshold: 0.30
+```
+
+## Configuration reference
+
+The following sections explain some of the configuration options and what their defaults are. They show only the `data` field of the ConfigMap for brevity.
+
+The most recent source of truth for these values can be found in the [values.yaml](https://github.com/giantswarm/cluster-autoscaler-app/blob/v1.30.3-gs1/helm/cluster-autoscaler-app/values.yaml) file of the `cluster-autoscaler-app`.
+
+### Scale down utilization threshold
+
+The `scaleDownUtilizationThreshold` defines the proportion between requested resources and capacity. Once utilization drops below this value, cluster autoscaler will consider a node as removable.
+
+Our default value is 70%, which means in order to scale down, one of the nodes has to have less utilization (CPU/memory) than this threshold. You can adjust this value to your needs as shown below:
+
+```yaml
+data:
+  values: |
+    configmap:
+      scaleDownUtilizationThreshold: 0.65
+```
+
+### Scan interval
+
+Defines what interval is used to review the state for taking a decision to scale up/down. Our default value is 10 seconds.
+
+```yaml
+data:
+  values: |
+    configmap:
+      scanInterval: "100s"
+```
+
+### Skip system pods
+
+By default, the cluster autoscaler will never delete nodes which run pods of the `kube-system` namespace (except `daemonset` pods). This rule can be deactivated by setting the following property to false.
+
+```yaml
+data:
+  values: |
+    configmap:
+      skipNodesWithSystemPods: "false"
+```
+
+### Skip pods with local storage
+
+The cluster autoscaler by default deletes nodes with pods using local storage (`hostPath` or `emptyDir`). In case you want to protect these nodes from removal, you can to set the following property to true.
+
+```yaml
+data:
+  values: |
+    configmap:
+      skipNodesWithLocalStorage: "true"
+```
+
+### Balance similar node groups
+
+The cluster autoscaler by default doesn't differentiate between node groups when scaling. In case you want to enable considering node groups, you need to set the following property to true.
+
+```yaml
+data:
+  values: |
+    configmap:
+      balanceSimilarNodeGroups: "true"
+```
+
+Read [the Kubernetes autoscaler FAQ](https://github.com/kubernetes/autoscaler/blob/master/cluster-autoscaler/FAQ.md) to learn more about the cluster autoscaler and its configuration options.

src/layouts/shortcodes/autoscaling_supported_versions.html

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+AWS