K8S控制节点高可用是在Kubernetes集群中确保控制节点的可用性和容错能力。通过搭建控制节点的高可用环境，可以防止单点故障导致整个Kubernetes集群不可用。本文将详细介绍实现K8S控制节点高可用的步骤及代码示例。

一、流程概述
实现K8S控制节点高可用的流程如下所示：

步骤 | 操作
-------|-----------------------
1 | 搭建etcd集群
2 | 配置kube-apiserver高可用
3 | 配置kube-controller-manager高可用
4 | 配置kube-scheduler高可用

接下来，我们将依次介绍每一个步骤的具体操作及代码示例。

二、搭建etcd集群
在实现K8S控制节点高可用之前，首先需要搭建etcd集群，用于存储Kubernetes集群的状态信息。

以下是搭建etcd集群的代码示例：

```shell
# 创建etcd证书配置文件
$ vi etcd-csr.json
{
"CN": "etcd",
"key": {
"algo": "rsa",
"size": 2048
},
"names": [
{
"C": "CN",
"L": "Shanghai",
"O": "etcd",
"OU": "etcd",
"ST": "Shanghai"
}
]
}

# 生成etcd证书
$ cfssl gencert -ca=ca.pem -ca-key=ca-key.pem -config=ca-config.json -profile=kubernetes etcd-csr.json | cfssljson -bare etcd

# 创建etcd配置文件
$ vi etcd.yaml
name: etcd0
data-dir: /var/lib/etcd
initial-advertise-peer-urls: https://192.168.0.1:2380
listen-peer-urls: https://192.168.0.1:2380
listen-client-urls: https://192.168.0.1:2379,http://127.0.0.1:2379
advertise-client-urls: https://192.168.0.1:2379
initial-cluster-token: k8s-etcd
initial-cluster: etcd0=https://192.168.0.1:2380,etcd1=https://192.168.0.2:2380,etcd2=https://192.168.0.3:2380
initial-cluster-state: new
client-transport-security:
key-file: /etc/kubernetes/pki/etcd/etcd-key.pem
cert-file: /etc/kubernetes/pki/etcd/etcd.pem
trusted-ca-file: /etc/kubernetes/pki/etcd/ca.pem
peer-transport-security:
key-file: /etc/kubernetes/pki/etcd/etcd-key.pem
cert-file: /etc/kubernetes/pki/etcd/etcd.pem
trusted-ca-file: /etc/kubernetes/pki/etcd/ca.pem

# 启动etcd集群
$ etcd --config-file=etcd.yaml
```

三、配置kube-apiserver高可用
接下来，需要配置kube-apiserver的高可用，确保在主节点故障时能够切换到备用节点。

以下是配置kube-apiserver高可用的代码示例：

```shell
# 创建kube-apiserver证书配置文件
$ vi kube-apiserver-csr.json
{
"CN": "kubernetes",
"key": {
"algo": "rsa",
"size": 2048
},
"names": [
{
"C": "CN",
"L": "Shanghai",
"O": "k8s",
"OU": "k8s",
"ST": "Shanghai"
}
]
}

# 生成kube-apiserver证书
$ cfssl gencert -ca=ca.pem -ca-key=ca-key.pem -config=ca-config.json -profile=kubernetes kube-apiserver-csr.json | cfssljson -bare kube-apiserver

# 创建kube-apiserver配置文件
$ vi kube-apiserver.yaml
apiVersion: v1
kind: Pod
metadata:
name: kube-apiserver
namespace: kube-system
spec:
hostNetwork: true
containers:
- name: kube-apiserver
image: k8s.gcr.io/kube-apiserver:v1.20.0
command:
- kube-apiserver
- --etcd-servers=https://192.168.0.1:2379,https://192.168.0.2:2379,https://192.168.0.3:2379
- --service-cluster-ip-range=10.0.0.0/24
- --advertise-address=192.168.0.1
- --bind-address=192.168.0.1
- --secure-port=6443
- --tls-cert-file=/etc/kubernetes/pki/apiserver/kube-apiserver.pem
- --tls-private-key-file=/etc/kubernetes/pki/apiserver/kube-apiserver-key.pem
- --client-ca-file=/etc/kubernetes/pki/apiserver/ca.pem
- --service-account-key-file=/etc/kubernetes/pki/apiserver/service-account.pem
- --etcd-ca-file=/etc/kubernetes/pki/etcd/ca.pem
- --etcd-cert-file=/etc/kubernetes/pki/etcd/etcd.pem
- --etcd-key-file=/etc/kubernetes/pki/etcd/etcd-key.pem
- --etcd-servers-overrides=/events#https://127.0.0.1:4001
- --event-ttl=1h
ports:
- name: https
containerPort: 6443
hostPort: 6443
protocol: TCP
volumeMounts:
- name: k8s-certs
mountPath: /etc/kubernetes/pki
readOnly: true
volumes:
- name: k8s-certs
hostPath:
path: /etc/kubernetes/pki

# 创建kube-apiserver服务
$ kubectl apply -f kube-apiserver.yaml
```

四、配置kube-controller-manager高可用
继续配置kube-controller-manager的高可用，确保在主节点故障时能够切换到备用节点。

以下是配置kube-controller-manager高可用的代码示例：

```shell
# 创建kube-controller-manager配置文件
$ vi kube-controller-manager.yaml
apiVersion: v1
kind: Pod
metadata:
name: kube-controller-manager
namespace: kube-system
spec:
hostNetwork: true
containers:
- name: kube-controller-manager
image: k8s.gcr.io/kube-controller-manager:v1.20.0
command:
- kube-controller-manager
- --kubeconfig=/etc/kubernetes/controller-manager.conf
- --allocate-node-cidrs=false
- --cluster-cidr=192.168.0.0/16
- --service-cluster-ip-range=10.0.0.0/24
- --controllers=*,bootstrapsigner,tokencleaner
- --leader-elect=true
- --use-service-account-credentials=true
- --cluster-signing-cert-file=/etc/kubernetes/pki/controller-manager/ca.pem
- --cluster-signing-key-file=/etc/kubernetes/pki/controller-manager/ca-key.pem
volumeMounts:
- name: controller-manager-certs
mountPath: /etc/kubernetes/pki
readOnly: true
volumes:
- name: controller-manager-certs
hostPath:
path: /etc/kubernetes/pki
hostPath:
path: /etc/kubernetes/admin.conf
type: FileOrDirectory

# 创建kube-controller-manager服务
$ kubectl apply -f kube-controller-manager.yaml
```

五、配置kube-scheduler高可用
最后，配置kube-scheduler的高可用，确保在主节点故障时能够切换到备用节点。

以下是配置kube-scheduler高可用的代码示例：

```shell
# 创建kube-scheduler配置文件
$ vi kube-scheduler.yaml
apiVersion: v1
kind: Pod
metadata:
name: kube-scheduler
namespace: kube-system
spec:
hostNetwork: true
containers:
- name: kube-scheduler
image: k8s.gcr.io/kube-scheduler:v1.20.0
command:
- kube-scheduler
- --kubeconfig=/etc/kubernetes/scheduler.conf
- --bind-address=127.0.0.1
- --leader-elect=true
volumeMounts:
- name: scheduler-certs
mountPath: /etc/kubernetes/pki
readOnly: true
volumes:
- name: scheduler-certs
hostPath:
path: /etc/kubernetes/pki
hostPath:
path: /etc/kubernetes/admin.conf
type: FileOrDirectory

# 创建kube-scheduler服务
$ kubectl apply -f kube-scheduler.yaml
```

通过以上步骤，我们成功实现了K8S控制节点的高可用。当主节点故障时，备用节点会自动接管控制平面的工作，确保整个Kubernetes集群的运行稳定。

感谢您耐心阅读本文，希望对于实现K8S控制节点高可用有所帮助。