使用kubeadm搭建一个k8s集群

使用kubeadm搭建一个k8s集群

kubeadm是官方社区推出的一个用于快速部署kubernetes集群的工具。

这个工具能通过两条指令完成一个kubernetes集群的部署：

# 创建一个 Master 节点$ kubeadm init# 将一个 Node 节点加入到当前集群中$ kubeadm join

1. 安装要求

在开始之前，部署Kubernetes集群机器需要满足以下几个条件：

一台或多台机器，操作系统 CentOS7.x-86_x64硬件配置：2GB或更多内存，2个CPU或更多CPU，硬盘30GB或更多可以联网，需要拉取镜像，如果服务器不能上网，需要提前下载镜像并导入节点

2. 准备环境

3台机器执行以下操作：

# 关闭防火墙systemctl stop firewalldsystemctl disable firewalld# 关闭selinuxsed -i 's/enforcing/disabled/' /etc/selinux/config # 永久setenforce 0 # 临时# 关闭swapswapoff -a # 临时sed -ri 's/.*swap.*/#&/' /etc/fstab # 永久# 根据规划设置主机名hostnamectl set-hostname # 如果终端上显示的主机名还是原来的，则关闭当前终端，另起一个终端即可。# 配置主机名解析cat >> /etc/hosts << EOF192.168.152.140 master192.168.152.141 node1192.168.152.142 node2EOF# 将桥接的IPv4流量传递到iptables的链cat > /etc/sysctl.d/k8s.conf << EOFnet.bridge.bridge-nf-call-ip6tables = 1net.bridge.bridge-nf-call-iptables = 1EOFsysctl --system # 生效# 时间同步yum install ntpdate -yntpdate time.windows.com

3. 所有节点安装Docker/kubeadm/kubelet

Kubernetes默认CRI（容器运行时）为Docker，因此先安装Docker。3台机器执行以下操作：

3.1 安装Docker

yum -y install yum-utilsyum-config-manager \ --add-repo \ yum install -y docker-ce-18.09.3 docker-ce-cli-18.09.3 containerd.iosystemctl start dockersystemctl enable docker$ cat > /etc/docker/daemon.json << EOF{ "registry-mirrors": ["systemctl daemon-reload#重启docker$ systemctl restart docker

3.2 添加阿里云YUM软件源

3台机器执行以下操作：

$ cat > /etc/yum.repos.d/kubernetes.repo << EOF[kubernetes]name=Kubernetesbaseurl=安装kubeadm，kubelet和kubectl

3台机器执行以下操作：

由于版本更新频繁，这里指定版本号部署(这里最好不要改版本，因为要注意与前面docker版本的兼容性，否则后续的 kubeadm init 会出问题)：

$ yum install -y kubelet-1.18.0 kubeadm-1.18.0 kubectl-1.18.0$ systemctl enable kubelet

4. 部署Kubernetes Master

在192.168.152.140（Master）执行：

$ kubeadm init \ --apiserver-advertise-address=192.168.152.140 \ --image-repository registry.aliyuncs.com/google_containers \ --kubernetes-version v1.18.0 \ --service-cidr=10.96.0.0/12 \ --pod-network-cidr=10.244.0.0/16

由于默认拉取镜像地址k8s.gcr.io国内无法访问，这里指定阿里云镜像仓库地址。

使用kubectl工具：

mkdir -p $HOME/.kubesudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/configsudo chown $(id -u):$(id -g) $HOME/.kube/config$ kubectl get nodes

5. 加入Kubernetes Node

向集群添加新节点node1和node2，在node1，node2中执行在kubeadm init输出结果中的下面几行：

$ kubeadm join 192.168.152.140:6443 --token esce21.q6hetwm8si29qxwn \ --discovery-token-ca-cert-hash sha256:00603a05805807501d7181c3d60b478788408cfe6cedefedb1f97569708be9c5

默认token有效期为24小时，当过期之后，该token就不可用了。这时就需要重新创建token，操作如下：

$ kubeadm token create --print-join-command #将输出结果复制，在要加入的结点中粘贴执行

6. 部署CNI网络插件

以下操作只在master执行：

kubectl apply -f get pods -n kube-systemNAME READY STATUS RESTARTS AGEkube-flannel-ds-amd64-2pc95 1/1 Running 0 72s

如果以上kubectl apply命令连不上网，则可以用以下操作代替：

touch kube-flannel.yml #创建文件vi kube-flannel.yml #编辑文件，内容如下

---apiVersion: policy/v1beta1kind: PodSecurityPolicymetadata: 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/defaultspec: 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'] defaultAddCapabilities: [] requiredDropCapabilities: [] # Host namespaces hostPID: false hostIPC: false hostNetwork: true hostPorts: - min: 0 max: 65535 # SELinux seLinux: # SELinux is unsed in CaaSP rule: 'RunAsAny'---kind: ClusterRoleapiVersion: rbac.authorization.k8s.io/v1beta1metadata: name: flannelrules: - 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: ClusterRoleBindingapiVersion: rbac.authorization.k8s.io/v1beta1metadata: name: flannelroleRef: apiGroup: rbac.authorization.k8s.io kind: ClusterRole name: flannelsubjects:- kind: ServiceAccount name: flannel namespace: kube-system---apiVersion: v1kind: ServiceAccountmetadata: name: flannel namespace: kube-system---kind: ConfigMapapiVersion: v1metadata: name: kube-flannel-cfg namespace: kube-system labels: tier: node app: flanneldata: cni-conf.json: | { "cniVersion": "0.2.0", "name": "cbr0", "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/v1kind: DaemonSetmetadata: name: kube-flannel-ds-amd64 namespace: kube-system labels: tier: node app: flannelspec: selector: matchLabels: app: flannel template: metadata: labels: tier: node app: flannel spec: affinity: nodeAffinity: requiredDuringSchedulingIgnoredDuringExecution: nodeSelectorTerms: - matchExpressions: - key: beta.kubernetes.io/os operator: In values: - linux - key: beta.kubernetes.io/arch operator: In values: - amd64 hostNetwork: true tolerations: - operator: Exists effect: NoSchedule serviceAccountName: flannel initContainers: - name: install-cni image: lizhenliang/flannel:v0.11.0-amd64 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: lizhenliang/flannel:v0.11.0-amd64 command: - /opt/bin/flanneld args: - --ip-masq - --kube-subnet-mgr resources: requests: cpu: "100m" memory: "50Mi" limits: cpu: "100m" memory: "50Mi" securityContext: privileged: false capabilities: add: ["NET_ADMIN"] 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

kubectl apply -f kube-flannel.ymlkubectl get pods -n kube-systemNAME READY STATUS RESTARTS AGEkube-flannel-ds-amd64-2pc95 1/1 Running 0 72s

7. 测试kubernetes集群

在master中执行：

在Kubernetes集群中创建一个pod，验证是否正常运行：

$ kubectl create deployment nginx --image=nginx$ kubectl expose deployment nginx --port=80 --type=NodePort$ kubectl get pod,svcNAME READY STATUS RESTARTS AGEpod/nginx-f89759699-lgg76 1/1 Running 0 2m34sNAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGEservice/kubernetes ClusterIP 10.96.0.1 443/TCP 11mservice/nginx NodePort 10.106.148.244 80:31990/TCP 2m30s

使用浏览器访问：​​http://任意一个node结点访问的IP地址:31990​​

（31990对应上面输出结果中的那个端口号）

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