[Kubernetes The Hard Way] Bootstrapping the Kubernetes Control Plane - Part 6

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بِسْمِ اللَّهِ الرَّحْمَنِ الرَّحِيم

Bootstrapping the Kubernetes Control Plane (Kubernetes The Hardway)

Lanjutkeunn, Lab part 6 In this lab you will bootstrap the Kubernetes control plane across three compute instances and configure it for high availability. You will also create an external load balancer that exposes the Kubernetes API Servers to remote clients. The following components will be installed on each node: Kubernetes API Server, Scheduler, and Controller Manager.

Prerequisites

The commands in this lab must be run on each controller instance: controller-0, controller-1, and controller-2

Running commands in parallel with tmux

tmux can be used to run commands on multiple compute instances at the same time. See the Running commands in parallel with tmux section in the Prerequisites lab.

Provision the Kubernetes Control Plane

Create the Kubernetes configuration directory:

sudo mkdir -p /etc/kubernetes/config

Download and Install the Kubernetes Controller Binaries

Download the official Kubernetes release binaries:

wget -q --show-progress --https-only --timestamping \
  "https://storage.googleapis.com/kubernetes-release/release/v1.12.0/bin/linux/amd64/kube-apiserver" \
  "https://storage.googleapis.com/kubernetes-release/release/v1.12.0/bin/linux/amd64/kube-controller-manager" \
  "https://storage.googleapis.com/kubernetes-release/release/v1.12.0/bin/linux/amd64/kube-scheduler" \
  "https://storage.googleapis.com/kubernetes-release/release/v1.12.0/bin/linux/amd64/kubectl"

Install the Kubernetes binaries:

{
  chmod +x kube-apiserver kube-controller-manager kube-scheduler kubectl
  sudo mv kube-apiserver kube-controller-manager kube-scheduler kubectl /usr/local/bin/
}

Configure the Kubernetes API Server

{
  sudo mkdir -p /var/lib/kubernetes/

  sudo mv ca.pem ca-key.pem kubernetes-key.pem kubernetes.pem \
    service-account-key.pem service-account.pem \
    encryption-config.yaml /var/lib/kubernetes/
}

Create the kube-apiserver.service systemd unit file:

cat <<EOF | sudo tee /etc/systemd/system/kube-apiserver.service
[Unit]
Description=Kubernetes API Server
Documentation=https://github.com/kubernetes/kubernetes

[Service]
ExecStart=/usr/local/bin/kube-apiserver \\
  --advertise-address=${INTERNAL_IP} \\
  --allow-privileged=true \\
  --apiserver-count=3 \\
  --audit-log-maxage=30 \\
  --audit-log-maxbackup=3 \\
  --audit-log-maxsize=100 \\
  --audit-log-path=/var/log/audit.log \\
  --authorization-mode=Node,RBAC \\
  --bind-address=0.0.0.0 \\
  --client-ca-file=/var/lib/kubernetes/ca.pem \\
  --enable-admission-plugins=Initializers,NamespaceLifecycle,NodeRestriction,LimitRanger,ServiceAccount,DefaultStorageClass,ResourceQuota \\
  --enable-swagger-ui=true \\
  --etcd-cafile=/var/lib/kubernetes/ca.pem \\
  --etcd-certfile=/var/lib/kubernetes/kubernetes.pem \\
  --etcd-keyfile=/var/lib/kubernetes/kubernetes-key.pem \\
  --etcd-servers=https://10.240.0.88:2379,https://10.240.0.161:2379,https://10.240.0.39:2379 \\
  --event-ttl=1h \\
  --experimental-encryption-provider-config=/var/lib/kubernetes/encryption-config.yaml \\
  --kubelet-certificate-authority=/var/lib/kubernetes/ca.pem \\
  --kubelet-client-certificate=/var/lib/kubernetes/kubernetes.pem \\
  --kubelet-client-key=/var/lib/kubernetes/kubernetes-key.pem \\
  --kubelet-https=true \\
  --runtime-config=api/all \\
  --service-account-key-file=/var/lib/kubernetes/service-account.pem \\
  --service-cluster-ip-range=10.32.0.0/24 \\
  --service-node-port-range=30000-32767 \\
  --tls-cert-file=/var/lib/kubernetes/kubernetes.pem \\
  --tls-private-key-file=/var/lib/kubernetes/kubernetes-key.pem \\
  --v=2
Restart=on-failure
RestartSec=5

[Install]
WantedBy=multi-user.target
EOF

Configure the Kubernetes Controller Manager

Move the kube-controller-manager kubeconfig into place:

sudo mv kube-controller-manager.kubeconfig /var/lib/kubernetes/

Create the kube-controller-manager.service systemd unit file:

cat <<EOF | sudo tee /etc/systemd/system/kube-controller-manager.service
[Unit]
Description=Kubernetes Controller Manager
Documentation=https://github.com/kubernetes/kubernetes

[Service]
ExecStart=/usr/local/bin/kube-controller-manager \\
  --address=0.0.0.0 \\
  --cluster-cidr=10.200.0.0/16 \\
  --cluster-name=kubernetes \\
  --cluster-signing-cert-file=/var/lib/kubernetes/ca.pem \\
  --cluster-signing-key-file=/var/lib/kubernetes/ca-key.pem \\
  --kubeconfig=/var/lib/kubernetes/kube-controller-manager.kubeconfig \\
  --leader-elect=true \\
  --root-ca-file=/var/lib/kubernetes/ca.pem \\
  --service-account-private-key-file=/var/lib/kubernetes/service-account-key.pem \\
  --service-cluster-ip-range=10.32.0.0/24 \\
  --use-service-account-credentials=true \\
  --v=2
Restart=on-failure
RestartSec=5

[Install]
WantedBy=multi-user.target
EOF

Configure the Kubernetes Scheduler

Move the kube-scheduler kubeconfig into place:

sudo mv kube-scheduler.kubeconfig /var/lib/kubernetes/

Create the kube-scheduler.yaml configuration file:

cat <<EOF | sudo tee /etc/kubernetes/config/kube-scheduler.yaml
apiVersion: componentconfig/v1alpha1
kind: KubeSchedulerConfiguration
clientConnection:
  kubeconfig: "/var/lib/kubernetes/kube-scheduler.kubeconfig"
leaderElection:
  leaderElect: true
EOF

Create the kube-scheduler.service systemd unit file:

cat <<EOF | sudo tee /etc/systemd/system/kube-scheduler.service
[Unit]
Description=Kubernetes Scheduler
Documentation=https://github.com/kubernetes/kubernetes

[Service]
ExecStart=/usr/local/bin/kube-scheduler \\
  --config=/etc/kubernetes/config/kube-scheduler.yaml \\
  --v=2
Restart=on-failure
RestartSec=5

[Install]
WantedBy=multi-user.target
EOF

Start the Controller Services

{
  sudo systemctl daemon-reload
  sudo systemctl enable kube-apiserver kube-controller-manager kube-scheduler
  sudo systemctl start kube-apiserver kube-controller-manager kube-scheduler
}

Verification

kubectl get componentstatuses --kubeconfig admin.kubeconfig

Output ```s [email protected]:~# kubectl get componentstatuses –kubeconfig admin.kubeconfig

NAME STATUS MESSAGE ERROR scheduler Healthy ok
controller-manager Healthy ok
etcd-1 Healthy {“health”:”true”}
etcd-0 Healthy {“health”:”true”}
etcd-2 Healthy {“health”:”true”}


## RBAC for Kubelet Authorization
In this section you will configure RBAC permissions to allow the Kubernetes API Server to access the Kubelet API on each worker node. Access to the Kubelet API is required for retrieving metrics, logs, and executing commands in pods.

> This tutorial sets the Kubelet --authorization-mode flag to Webhook. Webhook mode uses the [SubjectAccessReview](https://kubernetes.io/docs/admin/authorization/#checking-api-access) API to determine authorization.

Create the `system:kube-apiserver-to-kubelet` [ClusterRole](https://kubernetes.io/docs/admin/authorization/rbac/#role-and-clusterrole) with permissions to access the Kubelet API and perform most common tasks associated with managing pods:

```s
cat <<EOF | kubectl apply --kubeconfig admin.kubeconfig -f -
apiVersion: rbac.authorization.k8s.io/v1beta1
kind: ClusterRole
metadata:
  annotations:
    rbac.authorization.kubernetes.io/autoupdate: "true"
  labels:
    kubernetes.io/bootstrapping: rbac-defaults
  name: system:kube-apiserver-to-kubelet
rules:
  - apiGroups:
      - ""
    resources:
      - nodes/proxy
      - nodes/stats
      - nodes/log
      - nodes/spec
      - nodes/metrics
    verbs:
      - "*"
EOF

The Kubernetes API Server authenticates to the Kubelet as the kubernetes user using the client certificate as defined by the --kubelet-client-certificate flag.

Bind the system:kube-apiserver-to-kubelet ClusterRole to the kubernetes user:

cat <<EOF | kubectl apply --kubeconfig admin.kubeconfig -f -
apiVersion: rbac.authorization.k8s.io/v1beta1
kind: ClusterRoleBinding
metadata:
  name: system:kube-apiserver
  namespace: ""
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: system:kube-apiserver-to-kubelet
subjects:
  - apiGroup: rbac.authorization.k8s.io
    kind: User
    name: kubernetes
EOF

Lanjutnye: Bootstrapping the Kubernetes Worker Nodes - Part 7

Gaskunnnn

Referensi

Happy, Enjoy Ngoprek ~

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