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08-bootstrapping-kubernetes-controllers.md

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Bootstrapping the Kubernetes Control Plane

Provision the Kubernetes Control Plane

Download and copy official Kubernetes release binaries

wget -q --show-progress --https-only --timestamping \
  "https://storage.googleapis.com/kubernetes-release/release/v1.10.2/bin/linux/amd64/kube-apiserver" \
  "https://storage.googleapis.com/kubernetes-release/release/v1.10.2/bin/linux/amd64/kube-controller-manager" \
  "https://storage.googleapis.com/kubernetes-release/release/v1.10.2/bin/linux/amd64/kube-scheduler" \
  "https://storage.googleapis.com/kubernetes-release/release/v1.10.2/bin/linux/amd64/kubectl"

for i in k8s-controller1 k8s-controller2 k8s-controller3; do
scp kube-apiserver kube-controller-manager kube-scheduler \
kubectl defo@${i}:~/
done

Install the Kubernetes binaries

Commands will be run on each controller instance: k8s-controller1, k8s-controller2, k8s-controller3.

{
  sudo mkdir -p /etc/kubernetes/config
  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

{
INTERNAL_IP=`nslookup $(hostname -s)| awk '/^Address: / { print $2 }'`

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://10.98.95.11:2379,https://10.98.95.12:2379,https://10.98.95.13:2379 \\
  --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=10.98.96.0/24 \\
  --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=10.98.100.0/22 \\
  --allocate-node-cidrs=true \\
  --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=10.98.96.0/24 \\
  --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
}

Output

Created symlink /etc/systemd/system/multi-user.target.wants/kube-apiserver.service → /etc/systemd/system/kube-apiserver.service.
Created symlink /etc/systemd/system/multi-user.target.wants/kube-controller-manager.service → /etc/systemd/system/kube-controller-manager.service.
Created symlink /etc/systemd/system/multi-user.target.wants/kube-scheduler.service → /etc/systemd/system/kube-scheduler.service.
defo@k8s-controller1:~$

Enable HTTP Health Checks

sudo apt-get update
sudo apt-get install -y nginx

cat > kubernetes.default.svc.cluster.local <<EOF
server {
  listen      80;
  server_name kubernetes.default.svc.cluster.local;

  location /healthz {
     proxy_pass                    https://127.0.0.1:6443/healthz;
     proxy_ssl_trusted_certificate /var/lib/kubernetes/ca.pem;
  }
}
EOF

{
  sudo mv kubernetes.default.svc.cluster.local \
    /etc/nginx/sites-available/kubernetes.default.svc.cluster.local

  sudo ln -s /etc/nginx/sites-available/kubernetes.default.svc.cluster.local /etc/nginx/sites-enabled/
}

sudo systemctl restart nginx && sudo systemctl enable nginx

Verification

kubectl get componentstatuses --kubeconfig admin.kubeconfig

defo@k8s-controller1:~$ kubectl get componentstatuses --kubeconfig admin.kubeconfig
NAME                 STATUS    MESSAGE             ERROR
controller-manager   Healthy   ok                  
scheduler            Healthy   ok                  
etcd-1               Healthy   {"health":"true"}   
etcd-2               Healthy   {"health":"true"}   
etcd-0               Healthy   {"health":"true"} 

curl -H "Host: kubernetes.default.svc.cluster.local" -i http://127.0.0.1/healthz

defo@k8s-controller1:~$ curl -H "Host: kubernetes.default.svc.cluster.local" -i http://127.0.0.1/healthz
HTTP/1.1 200 OK
Server: nginx/1.14.0 (Ubuntu)
Date: Sat, 30 Jun 2018 21:13:56 GMT
Content-Type: text/plain; charset=utf-8
Content-Length: 2
Connection: keep-alive

RBAC for Kubelet Authorization

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

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