Auto-scaling nodes on EKS

For more information about auto-scaling managed nodes on EKS, refer to Amazon EKS managed node groups.

You can install the Kubernetes cluster autoscaler to auto-scale nodes.

Auto-scaling considerations for EKS

Managed controller and operations center workload

By assigning managed controller and operations center workload to a dedicated pool, the scaling down of nodes can be prevented by restricting eviction of managed controller or operations center deployments. Scale up will happen normally when resources need to be increased in order to deploy additional managed controllers, but scale down will only happen when the nodes are free of operations center or managed controller workload. This might be acceptable since controllers are meant to be stable and permanent, meaning that they are not ephemeral but long-lived.

This is achieved by adding the following annotation to operations center and managed controllers: "cluster-autoscaler.kubernetes.io/safe-to-evict": "false"

For operations center, the annotation is added to the cloudbees-core.yml in the CJOC "StatefulSet" definition under "spec - template - metadata - annotations"

apiVersion: "apps/v1"
kind: "StatefulSet"
metadata:
  name: cjoc
  labels:
    com.cloudbees.cje.type: cjoc
    com.cloudbees.cje.tenant: cjoc
spec:
  serviceName: cjoc
  replicas: 1
  updateStrategy:
    type: RollingUpdate
  template:
    metadata:
      annotations:
          cluster-autoscaler.kubernetes.io/safe-to-evict: "false"▼

For managed controllers, the annotation is added in the configuration page under the Advanced Configuration - YAML parameter. The YAML snippet to add would look like:

apiVersion: apps/v1
kind: StatefulSet
spec:
  template:
    metadata:
      annotations:
          cluster-autoscaler.kubernetes.io/safe-to-evict: "false"▼

Agent workload

For Pipelines, toleration can be added to podTemplate using the yaml parameter as follows:

  podTemplate(yaml: '''
  apiVersion: v1
  kind: Pod
  spec:
    tolerations:
    - key: nodeType
      operator: Equal
      value: build
      effect: NoSchedule
  ''', nodeSelector: 'workload=build', containers: [
    containerTemplate(name: 'maven', image: 'maven:3.8.5-jdk-11', command: 'sleep', args: '99d')
  ]) {
    node(POD_LABEL) {
      stage('Run maven') {
        container('maven') {
          sh 'mvn --version'
        }
      }
    }
  }▼

IAM policy

The worker running the cluster autoscaler needs access to certain resources and actions. To create an IAM policy, refer to Create an IAM policy and role.

Install cluster autoscaler

To install the cluster autoscaler, refer to Deploy the Cluster Autoscaler.