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Cluster Autoscaler

수요에 따라 k8s Node를 자동으로 추가하는 기능
리소스 부족으로 pod의 Node할당이 pending 될때 (scale-out)
미사용 Node가 있을때 (scale-in)
각 cloud provider 마다 각자의 cluster autoscaling 방법이 있음
AWS AutoScaling
cluster-autoscaler-policy.json
{ "Version": "2012-10-17", "Statement": [ { "Effect": "Allow", "Action": [ "autoscaling:DescribeAutoScalingGroups", "autoscaling:DescribeAutoScalingInstances", "autoscaling:DescribeLaunchConfigurations", "autoscaling:DescribeScalingActivities", "ec2:DescribeImages", "ec2:DescribeInstanceTypes", "ec2:DescribeLaunchTemplateVersions", "ec2:GetInstanceTypesFromInstanceRequirements", "eks:DescribeNodegroup" ], "Resource": ["*"] }, { "Effect": "Allow", "Action": [ "autoscaling:SetDesiredCapacity", "autoscaling:TerminateInstanceInAutoScalingGroup" ], "Resource": ["*"] } ] }
JSON
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aws iam create-policy \ --policy-name AmazonEKSClusterAutoscalerPolicy \ --policy-document file://cluster-autoscaler-policy.json
Shell
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eksctl create iamserviceaccount \ --cluster=skills-eks-cluster \ --namespace=kube-system \ --name=cluster-autoscaler \ --attach-policy-arn=arn:aws:iam::362708816803:policy/AmazonEKSClusterAutoscalerPolicy \ --override-existing-serviceaccounts \ --approve
Shell
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cluster-auto-scaler.yaml
--- apiVersion: v1 kind: ServiceAccount metadata: labels: k8s-addon: cluster-autoscaler.addons.k8s.io k8s-app: cluster-autoscaler name: cluster-autoscaler namespace: kube-system --- apiVersion: rbac.authorization.k8s.io/v1 kind: ClusterRole metadata: name: cluster-autoscaler labels: k8s-addon: cluster-autoscaler.addons.k8s.io k8s-app: cluster-autoscaler rules: - apiGroups: [""] resources: ["events", "endpoints"] verbs: ["create", "patch"] - apiGroups: [""] resources: ["pods/eviction"] verbs: ["create"] - apiGroups: [""] resources: ["pods/status"] verbs: ["update"] - apiGroups: [""] resources: ["endpoints"] resourceNames: ["cluster-autoscaler"] verbs: ["get", "update"] - apiGroups: [""] resources: ["nodes"] verbs: ["watch", "list", "get", "update"] - apiGroups: [""] resources: - "namespaces" - "pods" - "services" - "replicationcontrollers" - "persistentvolumeclaims" - "persistentvolumes" verbs: ["watch", "list", "get"] - apiGroups: ["extensions"] resources: ["replicasets", "daemonsets"] verbs: ["watch", "list", "get"] - apiGroups: ["policy"] resources: ["poddisruptionbudgets"] verbs: ["watch", "list"] - apiGroups: ["apps"] resources: ["statefulsets", "replicasets", "daemonsets"] verbs: ["watch", "list", "get"] - apiGroups: ["storage.k8s.io"] resources: ["storageclasses", "csinodes", "csidrivers", "csistoragecapacities"] verbs: ["watch", "list", "get"] - apiGroups: ["batch", "extensions"] resources: ["jobs"] verbs: ["get", "list", "watch", "patch"] - apiGroups: ["coordination.k8s.io"] resources: ["leases"] verbs: ["create"] - apiGroups: ["coordination.k8s.io"] resourceNames: ["cluster-autoscaler"] resources: ["leases"] verbs: ["get", "update"] --- apiVersion: rbac.authorization.k8s.io/v1 kind: Role metadata: name: cluster-autoscaler namespace: kube-system labels: k8s-addon: cluster-autoscaler.addons.k8s.io k8s-app: cluster-autoscaler rules: - apiGroups: [""] resources: ["configmaps"] verbs: ["create", "list", "watch"] - apiGroups: [""] resources: ["configmaps"] resourceNames: ["cluster-autoscaler-status", "cluster-autoscaler-priority-expander"] verbs: ["delete", "get", "update", "watch"] --- apiVersion: rbac.authorization.k8s.io/v1 kind: ClusterRoleBinding metadata: name: cluster-autoscaler labels: k8s-addon: cluster-autoscaler.addons.k8s.io k8s-app: cluster-autoscaler roleRef: apiGroup: rbac.authorization.k8s.io kind: ClusterRole name: cluster-autoscaler subjects: - kind: ServiceAccount name: cluster-autoscaler namespace: kube-system --- apiVersion: rbac.authorization.k8s.io/v1 kind: RoleBinding metadata: name: cluster-autoscaler namespace: kube-system labels: k8s-addon: cluster-autoscaler.addons.k8s.io k8s-app: cluster-autoscaler roleRef: apiGroup: rbac.authorization.k8s.io kind: Role name: cluster-autoscaler subjects: - kind: ServiceAccount name: cluster-autoscaler namespace: kube-system --- apiVersion: apps/v1 kind: Deployment metadata: name: cluster-autoscaler namespace: kube-system labels: app: cluster-autoscaler spec: replicas: 1 selector: matchLabels: app: cluster-autoscaler template: metadata: labels: app: cluster-autoscaler annotations: prometheus.io/scrape: "true" prometheus.io/port: "8085" spec: priorityClassName: system-cluster-critical securityContext: runAsNonRoot: true runAsUser: 65534 fsGroup: 65534 seccompProfile: type: RuntimeDefault serviceAccountName: cluster-autoscaler containers: - image: registry.k8s.io/autoscaling/cluster-autoscaler:v1.26.2 name: cluster-autoscaler resources: limits: cpu: 100m memory: 600Mi requests: cpu: 100m memory: 600Mi command: - ./cluster-autoscaler - --v=4 - --stderrthreshold=info - --cloud-provider=aws - --skip-nodes-with-local-storage=false - --expander=least-waste - --node-group-auto-discovery=asg:tag=k8s.io/cluster-autoscaler/enabled,k8s.io/cluster-autoscaler/skills-eks-cluster - --balance-similar-node-groups - --skip-nodes-with-system-pods=false volumeMounts: - name: ssl-certs mountPath: /etc/ssl/certs/ca-certificates.crt # /etc/ssl/certs/ca-bundle.crt for Amazon Linux Worker Nodes readOnly: true imagePullPolicy: "Always" securityContext: allowPrivilegeEscalation: false capabilities: drop: - ALL readOnlyRootFilesystem: true volumes: - name: ssl-certs hostPath: path: "/etc/ssl/certs/ca-bundle.crt"
YAML
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kubectl apply -f cluster-auto-scaler.yaml
Shell
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kubectl patch deployment cluster-autoscaler \ -n kube-system \ -p '{"spec":{"template":{"metadata":{"annotations":{"cluster-autoscaler.kubernetes.io/safe-to-evict": "false"}}}}}'
Shell
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kubectl -n kube-system logs -f deployment.apps/cluster-autoscaler kubectl get nodes
Shell
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