|
| 1 | +--- |
| 2 | +title: Cluster Autoscaling |
| 3 | +linkTitle: Cluster Autoscaling |
| 4 | +description: >- |
| 5 | + Automatically manage the nodes in your cluster to adapt to demand. |
| 6 | +content_type: concept |
| 7 | +weight: 120 |
| 8 | +--- |
| 9 | + |
| 10 | +<!-- overview --> |
| 11 | + |
| 12 | +Kubernetes requires {{< glossary_tooltip text="nodes" term_id="node" >}} in your cluster to |
| 13 | +run {{< glossary_tooltip text="pods" term_id="pod" >}}. This means providing capacity for |
| 14 | +the workload Pods and for Kubernetes itself. |
| 15 | + |
| 16 | +You can adjust the amount of resources available in your cluster automatically: |
| 17 | +_node autoscaling_. You can either change the number of nodes, or change the capacity |
| 18 | +that nodes provide. The first approach is referred to as _horizontal scaling_, while the |
| 19 | +second is referred to as _vertical scaling_. |
| 20 | + |
| 21 | +Kubernetes can even provide multidimensional automatic scaling for nodes. |
| 22 | + |
| 23 | +<!-- body --> |
| 24 | + |
| 25 | +## Manual node management |
| 26 | + |
| 27 | +You can manually manage node-level capacity, where you configure a fixed amount of nodes; |
| 28 | +you can use this approach even if the provisioning (the process to set up, manage, and |
| 29 | +decommission) for these nodes is automated. |
| 30 | + |
| 31 | +This page is about taking the next step, and automating management of the amount of |
| 32 | +node capacity (CPU, memory, and other node resources) available in your cluster. |
| 33 | + |
| 34 | +## Automatic horizontal scaling {#autoscaling-horizontal} |
| 35 | + |
| 36 | +### Cluster Autoscaler |
| 37 | + |
| 38 | +You can use the [Cluster Autoscaler](https://github.com/kubernetes/autoscaler/tree/master/cluster-autoscaler) to manage the scale of your nodes automatically. |
| 39 | +The cluster autoscaler can integrate with a cloud provider, or with Kubernetes' |
| 40 | +[cluster API](https://github.com/kubernetes/autoscaler/blob/c6b754c359a8563050933a590f9a5dece823c836/cluster-autoscaler/cloudprovider/clusterapi/README.md), |
| 41 | +to achieve the actual node management that's needed. |
| 42 | + |
| 43 | +The cluster autoscaler adds nodes when there are unschedulable Pods, and |
| 44 | +removes nodes when those nodes are empty. |
| 45 | + |
| 46 | +#### Cloud provider integrations {#cluster-autoscaler-providers} |
| 47 | + |
| 48 | +The [README](https://github.com/kubernetes/autoscaler/tree/c6b754c359a8563050933a590f9a5dece823c836/cluster-autoscaler#readme) |
| 49 | +for the cluster autoscaler lists some of the cloud provider integrations |
| 50 | +that are available. |
| 51 | + |
| 52 | +## Cost-aware multidimensional scaling {#autoscaling-multi-dimension} |
| 53 | + |
| 54 | +### Karpenter {#autoscaler-karpenter} |
| 55 | + |
| 56 | +[Karpenter](https://karpenter.sh/) supports direct node management, via |
| 57 | +plugins that integrate with specific cloud providers, and can manage nodes |
| 58 | +for you whilst optimizing for overall cost. |
| 59 | + |
| 60 | +> Karpenter automatically launches just the right compute resources to |
| 61 | +> handle your cluster's applications. It is designed to let you take |
| 62 | +> full advantage of the cloud with fast and simple compute provisioning |
| 63 | +> for Kubernetes clusters. |
| 64 | +
|
| 65 | +The Karpenter tool is designed to integrate with a cloud provider that |
| 66 | +provides API-driven server management, and where the price information for |
| 67 | +available servers is also available via a web API. |
| 68 | + |
| 69 | +For example, if you start some more Pods in your cluster, the Karpenter |
| 70 | +tool might buy a new node that is larger than one of the nodes you are |
| 71 | +already using, and then shut down an existing node once the new node |
| 72 | +is in service. |
| 73 | + |
| 74 | +#### Cloud provider integrations {#karpenter-providers} |
| 75 | + |
| 76 | +{{% thirdparty-content vendor="true" %}} |
| 77 | + |
| 78 | +There are integrations available between Karpenter's core and the following |
| 79 | +cloud providers: |
| 80 | + |
| 81 | +- [Amazon Web Services](https://github.com/aws/karpenter-provider-aws) |
| 82 | +- [Azure](https://github.com/Azure/karpenter-provider-azure) |
| 83 | + |
| 84 | + |
| 85 | +## Related components |
| 86 | + |
| 87 | +### Descheduler |
| 88 | + |
| 89 | +The [descheduler](https://github.com/kubernetes-sigs/descheduler) can help you |
| 90 | +consolidate Pods onto a smaller number of nodes, to help with automatic scale down |
| 91 | +when the cluster has space capacity. |
| 92 | + |
| 93 | +### Sizing a workload based on cluster size |
| 94 | + |
| 95 | +#### Cluster proportional autoscaler |
| 96 | + |
| 97 | +For workloads that need to be scaled based on the size of the cluster (for example |
| 98 | +`cluster-dns` or other system components), you can use the |
| 99 | +[_Cluster Proportional Autoscaler_](https://github.com/kubernetes-sigs/cluster-proportional-autoscaler).<br /> |
| 100 | + |
| 101 | +The Cluster Proportional Autoscaler watches the number of schedulable nodes |
| 102 | +and cores, and scales the number of replicas of the target workload accordingly. |
| 103 | + |
| 104 | +#### Cluster proportional vertical autoscaler |
| 105 | + |
| 106 | +If the number of replicas should stay the same, you can scale your workloads vertically according to the cluster size using |
| 107 | +the [_Cluster Proportional Vertical Autoscaler_](https://github.com/kubernetes-sigs/cluster-proportional-vertical-autoscaler). |
| 108 | +This project is in **beta** and can be found on GitHub. |
| 109 | + |
| 110 | +While the Cluster Proportional Autoscaler scales the number of replicas of a workload, the Cluster Proportional Vertical Autoscaler |
| 111 | +adjusts the resource requests for a workload (for example a Deployment or DaemonSet) based on the number of nodes and/or cores |
| 112 | +in the cluster. |
| 113 | + |
| 114 | + |
| 115 | +## {{% heading "whatsnext" %}} |
| 116 | + |
| 117 | +- Read about [workload-level autoscaling](/docs/concepts/workloads/autoscaling/) |
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