k8s安装flannel网络插件

安装Flannel网络插件需要以下步骤：

1. 在所有节点上安装flannel二进制文件：

$ wget https://github.com/coreos/flannel/releases/download/v0.13.0/flannel-v0.13.0-linux-amd64.tar.gz
$ tar -xvf flannel-v0.13.0-linux-amd64.tar.gz
$ cd flannel-v0.13.0-linux-amd64
$ sudo cp flanneld /usr/local/bin/
$ sudo cp mk-docker-opts.sh /usr/local/bin/

2. 创建flannel配置文件 `/etc/kubernetes/cni/net.d/10-flannel.conf`：

{
    "cniVersion": "0.3.1",
    "name": "flannel",
    "type": "flannel",
    "delegate": {
        "isDefaultGateway": true
    }
}

3. 在所有节点上启动flannel服务：

$ sudo systemctl start flanneld

4. 验证flannel是否运行正常：

$ sudo systemctl status flanneld

5. 在Master节点上检查kubelet配置文件 `/etc/kubernetes/kubelet.conf`是否包含以下内容：

apiVersion: v1
clusters:
- cluster:
    certificate-authority: /etc/kubernetes/pki/ca.crt
    server: https://127.0.0.1:6443
  name: kubernetes
contexts:
- context:
    cluster: kubernetes
    user: system:node:<node-name>
  name: default
current-context: default
kind: Config
preferences: {}
users:
- name: system:node:<node-name>
  user:
    client-certificate: /etc/kubernetes/pki/apiserver-kubelet-client.crt
    client-key: /etc/kubernetes/pki/apiserver-kubelet-client.key

6. 在Master节点上创建kube-flannel.yml文件：

apiVersion: v1
kind: ConfigMap
metadata:
  name: kube-flannel-cfg
  namespace: kube-system
  labels:
    tier: node
    app: flannel
data:
  cni-conf.json: |
    {
      "name": "cbr0",
      "cniVersion": "0.3.1",
      "plugins": [
        {
          "type": "flannel",
          "delegate": {
            "isDefaultGateway": true
          }
        },
        {
          "type": "portmap",
          "capabilities": {
            "portMappings": true
          }
        }
      ]
    }
  net-conf.json: |
    {
      "Network": "10.244.0.0/16",
      "Backend": {
        "Type": "vxlan"
      }
    }
---
apiVersion: extensions/v1beta1
kind: DaemonSet
metadata:
  name: kube-flannel-ds
  namespace: kube-system
  labels:
    tier: node
    app: flannel
spec:
  updateStrategy:
    type: RollingUpdate
  selector:
    matchLabels:
      tier: node
      app: flannel
  template:
    metadata:
      labels:
        tier: node
        app: flannel
    spec:
      hostNetwork: true
      containers:
      - name: kube-flannel
        image: quay.io/coreos/flannel:v0.13.0-rc2
        command:
        - /opt/bin/flanneld
        args:
        - --ip-masq
        - --kube-subnet-mgr
        - --iface=$(POD_IP)
        env:
        - name: POD_IP
          valueFrom:
            fieldRef:
              fieldPath: status.podIP
        securityContext:
          privileged: true
        volumeMounts:
        - name: flannel-cfg
          mountPath: /etc/kube-flannel/
      volumes:
      - name: flannel-cfg
        configMap:
          name: kube-flannel-cfg
      - name: run
        hostPath:
          path: /run
          type: ""

7. 在Master节点上应用kube-flannel.yml：

$ kubectl apply -f kube-flannel.yml

8. 检查所有节点上的flannel是否运行正常：

$ kubectl get pods -n kube-system

如果所有节点上的flannel状态都是Running，则表示flannel网络插件安装成功。