Cluster autoscaler configuration reference for Lokomotive

Introduction

The Cluster Autoscaler is a tool that automatically adjusts the size of a Kubernetes cluster when there are pods that failed to run in the cluster due to insufficient resources or when there are nodes that have been underutilized for an extended period of time and pods can be placed on other existing nodes.

Prerequisites

A Lokomotive cluster accessible via kubectl deployed on Packet.
For existing worker nodes in the cluster, you need to tag them manually for the Cluster Autoscaler to consider.
```
k8s-cluster-${cluster_name}
k8s-nodepool-${worker_pool}
```

Configuration

Currently Lokomotive supports the Cluster Autoscaler component only on the Packet platform. Support for other platforms will be added in the future.

Cluster Autoscaler component configuration example:

# cluster-autoscaler.lokocfg
component "cluster-autoscaler" {

  # Required arguments
  cluster_name = "cluster"
  worker_pool = "pool"

  # Optional arguments
  provider = "packet"
  namespace = "kube-system"
  min_workers = 1
  max_workers = 4
  scale_down_unneeded_time = "10m"
  scale_down_delay_after_add = "10m"
  scale_down_unready_time = "20m"

  packet {
    # Required arguments for Packet platform
    project_id = "0b5dc3d2-949a-447d-82cd-43fbdc1ae8c0"
    facility = "sjc1"

    # Optional arguments
    worker_type = "c3.small.x86"
    worker_channel = "stable"
  }
}

Attribute reference

Table of all the arguments accepted by the component.

Argument	Description	Default	Type	Required
`cluster_name`	Name of the cluster.	-	string	true
`worker_pool`	Name of the worker pool.	-	string	true
`namespace`	Namespace where the Cluster Autoscaler will be installed.	“kube-system”	string	false
`min_workers`	Minimum number of workers in the worker pool.	1	number	false
`max_workers`	Maximum number of workers in the worker pool.	4	number	false
`scale_down_unneeded_time`	How long a node should be unneeded before it is eligible for scale down.	“10m”	string	false
`scale_down_delay_after_add`	How long scale down should wait after a scale up.	“10m”	string	false
`scale_down_unready_time`	How long an unready node should be unneeded before it is eligible for scale down.	“20m”	string	false
`provider`	Supported provider, currently Packet.	“packet”	string	false
`service_monitor`	Specifies how metrics can be retrieved from a set of services.	false	bool	false
`packet.project_id`	Packet Project ID where the cluster is running.	-	string	true
`packet.facility`	Packet Facility where the cluster is running.	-	string	true
`packet.worker_type`	Machine type for workers spawned by the Cluster Autoscaler.	“c3.small.x86”	string	false
`packet_worker_channel`	Flatcar Container Linux channel to be used in workers spawned by the Cluster Autoscaler.	“stable”	string	false

Applying

To apply the cluster autoscaler component:

lokoctl component apply cluster-autoscaler

By default, the cluster Autoscaler pods run in the kube-system namespace

Deleting

To destroy the component:

lokoctl component delete cluster-autoscaler