[Metrics Server] Install metrics-server on Kubernetes.

Metrics Server là một dịch vụ chắc chắn sẽ phải cài.
Vì để tính năng HPA work well thì phải có metrics-server

Dưới đây là một số ảnh minh họa.

1) Introduce Metrics Server

2) Install Metrics Server on k8s

Việc cài đặt Vô cùng đơn giản.
https://github.com/kubernetes-sigs/metrics-server
Bạn apply file manifest sau:

kubectl apply -f https://github.com/kubernetes-sigs/metrics-server/releases/latest/download/components.yaml

Giờ bạn gõ command để nhìn thấy kết quả:

PS C:\Users\thang.tran> kubectl.exe top pod -n argocd
NAME                                               CPU(cores)   MEMORY(bytes)
argocd-application-controller-0                    29m          257Mi
argocd-applicationset-controller-bbf48bd7c-s8g6q   1m           22Mi
argocd-dex-server-7d757d85d5-s6jr2                 1m           25Mi
argocd-image-updater-595cbb8699-m2t8q              2m           35Mi
argocd-notifications-controller-7b7c9854dd-77287   1m           20Mi
argocd-redis-65596bf87-xcwdl                       2m           14Mi
argocd-repo-server-c996ccd4-bbrxb                  4m           54Mi
argocd-server-86576f9c7d-n7gj7                     1m           43Mi
busybox-deployment-6fcbfb5d48-dz56c                0m           0Mi

3) Pay attention to installing the Metrics Server on EKS

Bạn sẽ bị lỗi này:

kubectl describe apiservice v1beta1.metrics.k8s.io
Message: failing or missing response from https://IPAddress:4443/apis/metrics.k8s.io/v1beta1: 7 Get https://IPAddress:4443/apis/metrics.k8s.io/v1beta1: 7 net/http: request canceled while waiting for connection (Client.Timeout exceeded while awaiting headers)
Reason: FailedDiscoveryCheck

Do là bạn chưa mở Security Group

  # Extend node-to-node security group rules
  node_security_group_ntp_ipv4_cidr_block = ["169.254.169.123/32"]
  node_security_group_additional_rules = {
    ingress_self_all = {
      description = "Node to node all ports/protocols"
      protocol    = "-1"
      from_port   = 0
      to_port     = 0
      type        = "ingress"
      self        = true
    }
    egress_all = {
      description      = "Node all egress"
      protocol         = "-1"
      from_port        = 0
      to_port          = 0
      type             = "egress"
      cidr_blocks      = ["0.0.0.0/0"]
      ipv6_cidr_blocks = ["::/0"]
    }
    
    ## Security Group for Metrics Server
    ingress_cluster_metricserver = {
      description                   = "Cluster to node 4443 (Metrics Server)"
      protocol                      = "tcp"
      from_port                     = 4443
      to_port                       = 4443
      type                          = "ingress"
      source_cluster_security_group = true 
    }
    #https://github.com/kubernetes-sigs/metrics-server/issues/448
  }

https://github.com/kubernetes-sigs/metrics-server/issues/448