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08-bootstrapping-kubernetes-controllers.md

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部署控制节点

本部分将会在三台控制节点上部署 Kubernetes 控制服务，并配置高可用的集群架构。并且还会创建一个用于外部访问的负载均衡器。每个控制节点上需要部署的服务包括：Kubernetes API Server、Scheduler 以及 Controller Manager 等。

事前准备

以下命令需要在每台控制节点上面都运行一遍，包括 controller-0、controller-1 和 controller-2。可以使用 gcloud 命令登录每个控制节点。例如:

gcloud compute ssh controller-0

可以使用 tmux 同时登录到三点控制节点上，加快部署步骤。

部署 Kubernetes 控制平面

创建 Kubernetes 配置目录

sudo mkdir -p /etc/kubernetes/config

下载并安装 Kubernetes Controller 二进制文件

wget -q --show-progress --https-only --timestamping \
  "https://storage.googleapis.com/kubernetes-release/release/v1.18.6/bin/linux/amd64/kube-apiserver" \
  "https://storage.googleapis.com/kubernetes-release/release/v1.18.6/bin/linux/amd64/kube-controller-manager" \
  "https://storage.googleapis.com/kubernetes-release/release/v1.18.6/bin/linux/amd64/kube-scheduler" \
  "https://storage.googleapis.com/kubernetes-release/release/v1.18.6/bin/linux/amd64/kubectl"

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

配置 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/
}

使用节点的内网 IP 地址作为 API server 与集群内部成员的广播地址。首先查询当前节点的内网 IP 地址：

INTERNAL_IP=$(curl -s -H "Metadata-Flavor: Google" \
  http://metadata.google.internal/computeMetadata/v1/instance/network-interfaces/0/ip)

生成 kube-apiserver.service systemd 配置文件：

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=NamespaceLifecycle,NodeRestriction,LimitRanger,ServiceAccount,DefaultStorageClass,ResourceQuota \\
  --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://10.240.0.10:2379,https://10.240.0.11:2379,https://10.240.0.12:2379 \\
  --event-ttl=1h \\
  --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=true' \\
  --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

配置 Kubernetes Controller Manager

生成 kube-controller-manager.service systemd 配置文件：

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

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 \\
  --bind-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

配置 Kubernetes Scheduler

生成 kube-scheduler.service systemd 配置文件：

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

cat <<EOF | sudo tee /etc/kubernetes/config/kube-scheduler.yaml
apiVersion: kubescheduler.config.k8s.io/v1alpha1
kind: KubeSchedulerConfiguration
clientConnection:
  kubeconfig: "/var/lib/kubernetes/kube-scheduler.kubeconfig"
leaderElection:
  leaderElect: true
EOF

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

启动控制器服务

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

请等待 10 秒以便 Kubernetes API Server 初始化。

开启 HTTP 健康检查

Google Network Load Balancer 将用在在三个 API Server 之前作负载均衡，并可以终止 TLS 并验证客户端证书。但是该负载均衡仅支持 HTTP 健康检查，因而这里部署 nginx 来代理 API Server 的 /healthz 连接。

/healthz API 默认不需要认证。

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

验证

kubectl get componentstatuses --kubeconfig admin.kubeconfig

将输出结果

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

验证 Nginx HTTP 健康检查

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

将输出

HTTP/1.1 200 OK
Server: nginx/1.18.0 (Ubuntu)
Date: Sat, 18 Jul 2020 06:20:48 GMT
Content-Type: text/plain; charset=utf-8
Content-Length: 2
Connection: keep-alive
Cache-Control: no-cache, private
X-Content-Type-Options: nosniff

ok

记得在每台控制节点上面都运行一遍，包括 controller-0、controller-1 和 controller-2。

Kubelet RBAC 授权

本节将会配置 API Server 访问 Kubelet API 的 RBAC 授权。访问 Kubelet API 是获取 metrics、日志以及执行容器命令所必需的。

这里设置 Kubeket --authorization-mode 为 Webhook 模式。Webhook 模式使用 SubjectAccessReview API 来决定授权。

gcloud compute ssh controller-0

创建 system:kube-apiserver-to-kubelet ClusterRole 以允许请求 Kubelet API 和执行许用来管理 Pods 的任务:

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

Kubernetes API Server 使用客户端凭证授权 Kubelet 为 kubernetes 用户，此凭证用 --kubelet-client-certificate flag 来定义。

绑定 system:kube-apiserver-to-kubelet ClusterRole 到 kubernetes 用户:

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

Kubernetes 前端负载均衡器

本节将会建立一个位于 Kubernetes API Servers 前端的外部负载均衡器。 kubernetes-the-hard-way 静态 IP 地址将会配置在这个负载均衡器上。

本指南创建的虚拟机内部并没有操作负载均衡器的权限，需要到创建这些虚拟机的那台机器上去做下面的操作。

创建外部负载均衡器网络资源：

{
  KUBERNETES_PUBLIC_ADDRESS=$(gcloud compute addresses describe kubernetes-the-hard-way \
    --region $(gcloud config get-value compute/region) \
    --format 'value(address)')

  gcloud compute http-health-checks create kubernetes \
    --description "Kubernetes Health Check" \
    --host "kubernetes.default.svc.cluster.local" \
    --request-path "/healthz"

  gcloud compute firewall-rules create kubernetes-the-hard-way-allow-health-check \
    --network kubernetes-the-hard-way \
    --source-ranges 209.85.152.0/22,209.85.204.0/22,35.191.0.0/16 \
    --allow tcp

  gcloud compute target-pools create kubernetes-target-pool \
    --http-health-check kubernetes

  gcloud compute target-pools add-instances kubernetes-target-pool \
   --instances controller-0,controller-1,controller-2

  gcloud compute forwarding-rules create kubernetes-forwarding-rule \
    --address ${KUBERNETES_PUBLIC_ADDRESS} \
    --ports 6443 \
    --region $(gcloud config get-value compute/region) \
    --target-pool kubernetes-target-pool
}

验证

查询 kubernetes-the-hard-way 静态 IP 地址:

KUBERNETES_PUBLIC_ADDRESS=$(gcloud compute addresses describe kubernetes-the-hard-way \
  --region $(gcloud config get-value compute/region) \
  --format 'value(address)')

发送一个查询 Kubernetes 版本信息的 HTTP 请求

curl --cacert ca.pem https://${KUBERNETES_PUBLIC_ADDRESS}:6443/version

结果为

{
  "major": "1",
  "minor": "18",
  "gitVersion": "v1.18.6",
  "gitCommit": "dff82dc0de47299ab66c83c626e08b245ab19037",
  "gitTreeState": "clean",
  "buildDate": "2020-07-15T16:51:04Z",
  "goVersion": "go1.13.9",
  "compiler": "gc",
  "platform": "linux/amd64"
}

下一步：部署 Kubernetes Worker 节点。