【Kubernetes】kubeadm 安装集群（二）

环境

1. virtual box 6.1
2. centos 7.8
3. docker 19.03
4. kubernetes 1.20.2

安装必备软件

添加 Kubernetes 仓库

cat <<EOF > /etc/yum.repos.d/kubernetes.repo
[kubernetes]
name=Kubernetes
baseurl=https://mirrors.aliyun.com/kubernetes/yum/repos/kubernetes-el7-x86_64/
enabled=1
gpgcheck=1
repo_gpgcheck=1
gpgkey=https://mirrors.aliyun.com/kubernetes/yum/doc/yum-key.gpg https://mirrors.aliyun.com/kubernetes/yum/doc/rpm-package-key.gpg
EOF

安装软件

yum install -y kubelet kubeadm kubectl
systemctl enable kubelet && systemctl start kubelet

kubeadm 创建集群

初始化主节点

kubeadm init 
--image-repository registry.aliyuncs.com/google_containers 
--apiserver-advertise-address 192.168.56.101 
--pod-network-cidr 10.244.0.0/16 

--pod-network-cidr 10.244.0.0/16 是后面 flannel 网络插件默认值。

最终会看到输出如下的内容：

Your Kubernetes control-plane has initialized successfully!

To start using your cluster, you need to run the following as a regular user:

  mkdir -p $HOME/.kube
  sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
  sudo chown $(id -u):$(id -g) $HOME/.kube/config

Alternatively, if you are the root user, you can run:

  export KUBECONFIG=/etc/kubernetes/admin.conf

You should now deploy a pod network to the cluster.
Run "kubectl apply -f [podnetwork].yaml" with one of the options listed at:
  https://kubernetes.io/docs/concepts/cluster-administration/addons/

Then you can join any number of worker nodes by running the following on each as root:

kubeadm join 192.168.56.101:6443 --token ir22ai.to5rqixx90mscp4i 
    --discovery-token-ca-cert-hash sha256:efe632e2b03d00b873b888702882d8127f83540677034a0226cec599cd139050

配置 kubectl

  mkdir -p $HOME/.kube
  sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
  sudo chown $(id -u):$(id -g) $HOME/.kube/config

查看节点状态

[root@master ~]# kubectl get nodes
NAME     STATUS   ROLES                     AGE   VERSION
master   NotReady    control-plane,master   2m    v1.20.2

安装 flannel 插件

[root@master ~]# kubectl apply -f kube-flannel-aliyun.yml
podsecuritypolicy.policy/psp.flannel.unprivileged created
clusterrole.rbac.authorization.k8s.io/flannel created
clusterrolebinding.rbac.authorization.k8s.io/flannel created
serviceaccount/flannel created
configmap/kube-flannel-cfg created
daemonset.apps/kube-flannel-ds created

flannel.yml 的内容见附录。

加入工作节点

以下命令根据 kubeadm init 的最终输出来，拷贝最后两行的 kubeadm join 命令。

[root@node1 ~]# kubeadm join 192.168.56.101:6443 --token ir22ai.to5rqixx90mscp4i 
>     --discovery-token-ca-cert-hash sha256:efe632e2b03d00b873b888702882d8127f83540677034a0226cec599cd139050
[preflight] Running pre-flight checks
[preflight] Reading configuration from the cluster...
[preflight] FYI: You can look at this config file with 'kubectl -n kube-system get cm kubeadm-config -o yaml'
[kubelet-start] Writing kubelet configuration to file "/var/lib/kubelet/config.yaml"
[kubelet-start] Writing kubelet environment file with flags to file "/var/lib/kubelet/kubeadm-flags.env"
[kubelet-start] Starting the kubelet
[kubelet-start] Waiting for the kubelet to perform the TLS Bootstrap...

This node has joined the cluster:
* Certificate signing request was sent to apiserver and a response was received.
* The Kubelet was informed of the new secure connection details.

Run 'kubectl get nodes' on the control-plane to see this node join the cluster.

再次查看节点状态

[root@master ~]# kubectl get nodes
NAME     STATUS   ROLES                  AGE     VERSION
master   Ready    control-plane,master   9m23s   v1.20.2
node1    Ready    <none>                 78s     v1.20.2
node2    Ready    <none>                 68s     v1.20.2

查看 POD 状态

[root@master ~]# kubectl get pod --all-namespaces
NAMESPACE     NAME                             READY   STATUS    RESTARTS   AGE
kube-system   coredns-7f89b7bc75-9mff4         1/1     Running   0          9m43s
kube-system   coredns-7f89b7bc75-9qvqx         1/1     Running   0          9m43s
kube-system   etcd-master                      1/1     Running   0          9m52s
kube-system   kube-apiserver-master            1/1     Running   0          9m52s
kube-system   kube-controller-manager-master   1/1     Running   0          9m52s
kube-system   kube-flannel-ds-jjldk            1/1     Running   0          105s
kube-system   kube-flannel-ds-rjqln            1/1     Running   0          115s
kube-system   kube-flannel-ds-zp5xn            1/1     Running   0          4m42s
kube-system   kube-proxy-bs7ft                 1/1     Running   0          115s
kube-system   kube-proxy-g67nx                 1/1     Running   0          9m43s
kube-system   kube-proxy-w99js                 1/1     Running   0          105s
kube-system   kube-scheduler-master            1/1     Running   0          9m52s

如果在安装的过程中出现了问题，可以使用 kubeadm reset 命令还原状态。

kubectl 命令提示

yum install bash-completion
kubectl completion bash >/etc/bash_completion.d/kubectl

总结

介绍了使用 kubeadm 安装 Kubernetes 的方式。

附录

flannel.yml 内容

---
apiVersion: policy/v1beta1
kind: PodSecurityPolicy
metadata:
  name: psp.flannel.unprivileged
  annotations:
    seccomp.security.alpha.kubernetes.io/allowedProfileNames: docker/default
    seccomp.security.alpha.kubernetes.io/defaultProfileName: docker/default
    apparmor.security.beta.kubernetes.io/allowedProfileNames: runtime/default
    apparmor.security.beta.kubernetes.io/defaultProfileName: runtime/default
spec:
  privileged: false
  volumes:
    - configMap
    - secret
    - emptyDir
    - hostPath
  allowedHostPaths:
    - pathPrefix: "/etc/cni/net.d"
    - pathPrefix: "/etc/kube-flannel"
    - pathPrefix: "/run/flannel"
  readOnlyRootFilesystem: false
  # Users and groups
  runAsUser:
    rule: RunAsAny
  supplementalGroups:
    rule: RunAsAny
  fsGroup:
    rule: RunAsAny
  # Privilege Escalation
  allowPrivilegeEscalation: false
  defaultAllowPrivilegeEscalation: false
  # Capabilities
  allowedCapabilities: ["NET_ADMIN", "NET_RAW"]
  defaultAddCapabilities: []
  requiredDropCapabilities: []
  # Host namespaces
  hostPID: false
  hostIPC: false
  hostNetwork: true
  hostPorts:
    - min: 0
      max: 65535
  # SELinux
  seLinux:
    # SELinux is unused in CaaSP
    rule: "RunAsAny"
---
kind: ClusterRole
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: flannel
rules:
  - apiGroups: ["extensions"]
    resources: ["podsecuritypolicies"]
    verbs: ["use"]
    resourceNames: ["psp.flannel.unprivileged"]
  - apiGroups:
      - ""
    resources:
      - pods
    verbs:
      - get
  - apiGroups:
      - ""
    resources:
      - nodes
    verbs:
      - list
      - watch
  - apiGroups:
      - ""
    resources:
      - nodes/status
    verbs:
      - patch
---
kind: ClusterRoleBinding
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: flannel
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: flannel
subjects:
  - kind: ServiceAccount
    name: flannel
    namespace: kube-system
---
apiVersion: v1
kind: ServiceAccount
metadata:
  name: flannel
  namespace: kube-system
---
kind: ConfigMap
apiVersion: v1
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": {
            "hairpinMode": true,
            "isDefaultGateway": true
          }
        },
        {
          "type": "portmap",
          "capabilities": {
            "portMappings": true
          }
        }
      ]
    }
  net-conf.json: |
    {
      "Network": "10.244.0.0/16",
      "Backend": {
        "Type": "vxlan"
      }
    }
---
apiVersion: apps/v1
kind: DaemonSet
metadata:
  name: kube-flannel-ds
  namespace: kube-system
  labels:
    tier: node
    app: flannel
spec:
  selector:
    matchLabels:
      app: flannel
  template:
    metadata:
      labels:
        tier: node
        app: flannel
    spec:
      affinity:
        nodeAffinity:
          requiredDuringSchedulingIgnoredDuringExecution:
            nodeSelectorTerms:
              - matchExpressions:
                  - key: kubernetes.io/os
                    operator: In
                    values:
                      - linux
      hostNetwork: true
      priorityClassName: system-node-critical
      tolerations:
        - operator: Exists
          effect: NoSchedule
      serviceAccountName: flannel
      initContainers:
        - name: install-cni
          image: quay.io/coreos/flannel:v0.13.1-rc1
          command:
            - cp
          args:
            - -f
            - /etc/kube-flannel/cni-conf.json
            - /etc/cni/net.d/10-flannel.conflist
          volumeMounts:
            - name: cni
              mountPath: /etc/cni/net.d
            - name: flannel-cfg
              mountPath: /etc/kube-flannel/
      containers:
        - name: kube-flannel
          image: quay.io/coreos/flannel:v0.13.1-rc1
          command:
            - /opt/bin/flanneld
          args:
            - --ip-masq
            - --kube-subnet-mgr
            - --iface=enp0s8
          resources:
            requests:
              cpu: "100m"
              memory: "50Mi"
            limits:
              cpu: "100m"
              memory: "50Mi"
          securityContext:
            privileged: false
            capabilities:
              add: ["NET_ADMIN", "NET_RAW"]
          env:
            - name: POD_NAME
              valueFrom:
                fieldRef:
                  fieldPath: metadata.name
            - name: POD_NAMESPACE
              valueFrom:
                fieldRef:
                  fieldPath: metadata.namespace
          volumeMounts:
            - name: run
              mountPath: /run/flannel
            - name: flannel-cfg
              mountPath: /etc/kube-flannel/
      volumes:
        - name: run
          hostPath:
            path: /run/flannel
        - name: cni
          hostPath:
            path: /etc/cni/net.d
        - name: flannel-cfg
          configMap:
            name: kube-flannel-cfg