kubeadm搭建K8S集群

作者：@skyflask
转载本文请注明出处：https://www.cnblogs.com/skyflask/p/14620563.html

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目录

1. 安装要求
2. 准备环境
3. 安装Docker/kubeadm/kubelet【所有节点】
4. 部署Kubernetes Master
5. 加入Kubernetes Node
6. 部署容器网络（CNI）
7. 测试kubernetes集群
8. 部署 Dashboard
9. 遇到的问题

一、环境准备

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

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1	kubeadm init

# 将一个 Node 节点加入到当前集群中

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1	kubeadm join <Master节点的IP和端口 >

　　

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RAM，2个CPU或更多CPU，硬盘30GB或更多
• 集群中所有机器之间网络互通
• 可以访问外网，需要拉取镜像
• 禁止swap分区，swapoff -a   注释/etc/fstab里面关于swap的行

2. 准备环境

 

 

 

角色	IP
k8s-master	10.11.97.193
k8s-node1	10.11.99.141

关闭防火墙：

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1 2	$ systemctl stop firewalld $ systemctl disable firewalld

　　

关闭selinux：

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1 2	$ sed -i 's/enforcing/disabled/' /etc/selinux/config  # 永久 $ setenforce 0  # 临时

　　

关闭swap：

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1 2	$ swapoff -a  # 临时 $ vim /etc/fstab  # 永久

　　

设置主机名：

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1	$ hostnamectl set-hostname <hostname>

　　

在master添加hosts：

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$ cat >> /etc/hosts << EOF 10.11.97.193 k8s-master 10.11.99.141 k8s-node1 EOF

将桥接的IPv4流量传递到iptables的链：

　

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$ cat > /etc/sysctl.d/k8s.conf << EOF net.bridge.bridge-nf-call-ip6tables = 1 net.bridge.bridge-nf-call-iptables = 1 EOF

　　$ sysctl --system # 生效

时间同步：

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1 2	$ yum install ntpdate -y $ ntpdate time.windows.com

　　

3. 安装Docker/kubeadm/kubelet【所有节点】

Kubernetes默认CRI（容器运行时）为Docker，因此先安装Docker。

3.1 安装Docker

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$ wget https://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo -O /etc/yum.repos.d/docker-ce.repo $ yum -y install docker-ce $ systemctl enable docker && systemctl start docker

　　配置镜像下载加速器：

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$ cat > /etc/docker/daemon.json << EOF {   "registry-mirrors": ["https://b9pmyelo.mirror.aliyuncs.com"] } EOF $ systemctl restart docker $ docker info

　　

3.2 添加阿里云YUM软件源

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$ cat > /etc/yum.repos.d/kubernetes.repo << EOF [kubernetes] name=Kubernetes baseurl=https://mirrors.aliyun.com/kubernetes/yum/repos/kubernetes-el7-x86_64 enabled=1 gpgcheck=0 repo_gpgcheck=0 gpgkey=https://mirrors.aliyun.com/kubernetes/yum/doc/yum-key.gpg https://mirrors.aliyun.com/kubernetes/yum/doc/rpm-package-key.gpg EOF

　　

3.3 安装kubeadm，kubelet和kubectl

由于版本更新频繁，这里指定版本号部署：

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1 2	$ yum install -y kubelet-1.19.0 kubeadm-1.19.0 kubectl-1.19.0 $ systemctl enable kubelet

　　

4. 部署Kubernetes Master

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https://kubernetes.io/zh/docs/reference/setup-tools/kubeadm/kubeadm-init/#config-file   https://kubernetes.io/docs/setup/production-environment/tools/kubeadm/create-cluster-kubeadm/#initializing-your-control-plane-node

　在master上执行：

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$ kubeadm init \   --apiserver-advertise-address=10.11.97.193 \   --image-repository registry.aliyuncs.com/google_containers \   --kubernetes-version v1.19.0 \   --service-cidr=10.96.0.0/12 \   --pod-network-cidr=10.245.0.0/16 \   --ignore-preflight-errors=all

　　

• --apiserver-advertise-address 集群通告地址
• --image-repository 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
• --kubernetes-version K8s版本，与上面安装的一致
• --service-cidr 集群内部虚拟网络，Pod统一访问入口
• --pod-network-cidr Pod网络，，与下面部署的CNI网络组件yaml中保持一致

或者使用配置文件引导：

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$ vi kubeadm.conf apiVersion: kubeadm.k8s.io/v1beta2 kind: ClusterConfiguration kubernetesVersion: v1.18.0 imageRepository: registry.aliyuncs.com/google_containers networking:   podSubnet: 10.245.0.0/16   serviceSubnet: 10.96.0.0/12   $ kubeadm init --config kubeadm.conf --ignore-preflight-errors=all

　　

安装过程：

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[root@k8s-node3 ~]# kubeadm init \ >   --apiserver-advertise-address=10.11.97.193 \ >   --image-repository registry.aliyuncs.com/google_containers \ >   --kubernetes-version v1.19.0 \ >   --service-cidr=10.96.0.0/12 \ >   --pod-network-cidr=10.245.0.0/16 \ >   --ignore-preflight-errors=all W0404 15:15:58.088052    1450 configset.go:348] WARNING: kubeadm cannot validate component configs for API groups [kubelet.config.k8s.io kubeproxy.config.k8s.io] [init] Using Kubernetes version: v1.19.0 [preflight] Running pre-flight checks         [WARNING IsDockerSystemdCheck]: detected "cgroupfs" as the Docker cgroup driver. The recommended driver is "systemd". Please follow the guide at https://kubernetes.io/docs/setup/cri/         [WARNING SystemVerification]: this Docker version is not on the list of validated versions: 20.10.5. Latest validated version: 19.03 [preflight] Pulling images required for setting up a Kubernetes cluster [preflight] This might take a minute or two, depending on the speed of your internet connection [preflight] You can also perform this action in beforehand using 'kubeadm config images pull' [certs] Using certificateDir folder "/etc/kubernetes/pki" [certs] Generating "ca" certificate and key [certs] Generating "apiserver" certificate and key [certs] apiserver serving cert is signed for DNS names [k8s-master kubernetes kubernetes.default kubernetes.default.svc kubernetes.default.svc.cluster.local] and IPs [10.96.0.1 10.11.97.193] [certs] Generating "apiserver-kubelet-client" certificate and key [certs] Generating "front-proxy-ca" certificate and key [certs] Generating "front-proxy-client" certificate and key [certs] Generating "etcd/ca" certificate and key [certs] Generating "etcd/server" certificate and key [certs] etcd/server serving cert is signed for DNS names [k8s-master localhost] and IPs [10.11.97.193 127.0.0.1 ::1] [certs] Generating "etcd/peer" certificate and key [certs] etcd/peer serving cert is signed for DNS names [k8s-master localhost] and IPs [10.11.97.193 127.0.0.1 ::1] [certs] Generating "etcd/healthcheck-client" certificate and key [certs] Generating "apiserver-etcd-client" certificate and key [certs] Generating "sa" key and public key [kubeconfig] Using kubeconfig folder "/etc/kubernetes" [kubeconfig] Writing "admin.conf" kubeconfig file [kubeconfig] Writing "kubelet.conf" kubeconfig file [kubeconfig] Writing "controller-manager.conf" kubeconfig file [kubeconfig] Writing "scheduler.conf" kubeconfig file [kubelet-start] Writing kubelet environment file with flags to file "/var/lib/kubelet/kubeadm-flags.env" [kubelet-start] Writing kubelet configuration to file "/var/lib/kubelet/config.yaml" [kubelet-start] Starting the kubelet [control-plane] Using manifest folder "/etc/kubernetes/manifests" [control-plane] Creating static Pod manifest for "kube-apiserver" [control-plane] Creating static Pod manifest for "kube-controller-manager" [control-plane] Creating static Pod manifest for "kube-scheduler" [etcd] Creating static Pod manifest for local etcd in "/etc/kubernetes/manifests" [wait-control-plane] Waiting for the kubelet to boot up the control plane as static Pods from directory "/etc/kubernetes/manifests". This can take up to 4m0s [apiclient] All control plane components are healthy after 19.516063 seconds [upload-config] Storing the configuration used in ConfigMap "kubeadm-config" in the "kube-system" Namespace [kubelet] Creating a ConfigMap "kubelet-config-1.19" in namespace kube-system with the configuration for the kubelets in the cluster [upload-certs] Skipping phase. Please see --upload-certs [mark-control-plane] Marking the node k8s-master as control-plane by adding the label "node-role.kubernetes.io/master=''" [mark-control-plane] Marking the node k8s-master as control-plane by adding the taints [node-role.kubernetes.io/master:NoSchedule] [bootstrap-token] Using token: 9ibx2w.7lr713ygq3q6fz5d [bootstrap-token] Configuring bootstrap tokens, cluster-info ConfigMap, RBAC Roles [bootstrap-token] configured RBAC rules to allow Node Bootstrap tokens to get nodes [bootstrap-token] configured RBAC rules to allow Node Bootstrap tokens to post CSRs in order for nodes to get long term certificate credentials [bootstrap-token] configured RBAC rules to allow the csrapprover controller automatically approve CSRs from a Node Bootstrap Token [bootstrap-token] configured RBAC rules to allow certificate rotation for all node client certificates in the cluster [bootstrap-token] Creating the "cluster-info" ConfigMap in the "kube-public" namespace [kubelet-finalize] Updating "/etc/kubernetes/kubelet.conf" to point to a rotatable kubelet client certificate and key [addons] Applied essential addon: CoreDNS [addons] Applied essential addon: kube-proxy   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   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 10.11.97.193:6443 --token 9ibx2w.7lr713ygq3q6fz5d \     --discovery-token-ca-cert-hash sha256:292e77baeb776c807f797812616215e018a384beefec1dc1fc5f164951ca0b7d [root@k8s-node3 ~]#

　　

 

拷贝kubectl使用的连接k8s认证文件到默认路径：

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mkdir -p $HOME/.kube sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config sudo chown $(id -u):$(id -g) $HOME/.kube/config $ kubectl get nodes NAME         STATUS   ROLES    AGE   VERSION k8s-master   Ready    master   2m   v1.18.0

　　

5. 加入Kubernetes Node

在10.11.99.141上（Node）执行。

向集群添加新节点，执行在kubeadm init输出的kubeadm join命令：

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1	kubeadm join 10.11.97.193:6443 --token 9ibx2w.7lr713ygq3q6fz5d     --discovery-token-ca-cert-hash sha256:292e77baeb776c807f797812616215e018a384beefec1dc1fc5f164951ca0b7d

　　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：

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$ kubeadm token create $ kubeadm token list $ openssl x509 -pubkey -in /etc/kubernetes/pki/ca.crt | openssl rsa -pubin -outform der 2>/dev/null | openssl dgst -sha256 -hex | sed 's/^.* //' 63bca849e0e01691ae14eab449570284f0c3ddeea590f8da988c07fe2729e924   kubeadm join 10.11.97.193:6443 --token 9ibx2w.7lr713ygq3q6fz5d     --discovery-token-ca-cert-hash sha256:292e77baeb776c807f797812616215e018a384beefec1dc1fc5f164951ca0b7d

　　或者直接命令快捷生成：kubeadm token create --print-join-command

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1	https://kubernetes.io/docs/reference/setup-tools/kubeadm/kubeadm-join/

　　

6. 部署容器网络（CNI）

https://kubernetes.io/docs/setup/production-environment/tools/kubeadm/create-cluster-kubeadm/#pod-network

注意：只需要部署下面其中一个，推荐Calico。

Calico是一个纯三层的数据中心网络方案，Calico支持广泛的平台，包括Kubernetes、OpenStack等。

Calico 在每一个计算节点利用 Linux Kernel 实现了一个高效的虚拟路由器（ vRouter） 来负责数据转发，而每个 vRouter 通过 BGP 协议负责把自己上运行的 workload 的路由信息向整个 Calico 网络内传播。

此外，Calico 项目还实现了 Kubernetes 网络策略，提供ACL功能。

https://docs.projectcalico.org/getting-started/kubernetes/quickstart

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1	wget https://docs.projectcalico.org/manifests/calico.yaml

　　

下载完后还需要修改里面定义Pod网络（CALICO_IPV4POOL_CIDR），与前面kubeadm init指定的一样

修改完后应用清单：

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1 2	$ kubectl apply -f calico.yaml $ kubectl get pods -n kube-system

　　

7. 测试kubernetes集群

• 验证Pod工作
• 验证Pod网络通信
• 验证DNS解析

在Kubernetes集群中创建一个pod，验证是否正常运行：

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$ kubectl create deployment nginx --image=nginx $ kubectl expose deployment nginx --port=80 --type=NodePort $ kubectl get pod,svc

　　

8. 部署 Dashboard

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1	wget https://raw.githubusercontent.com/kubernetes/dashboard/v2.0.3/aio/deploy/recommended.yaml

　　默认Dashboard只能集群内部访问，修改Service为NodePort类型，暴露到外部

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$ vi recommended.yaml ... kind: Service apiVersion: v1 metadata:   labels:     k8s-app: kubernetes-dashboard   name: kubernetes-dashboard   namespace: kubernetes-dashboard spec:   ports:     - port: 443       targetPort: 8443       nodePort: 30001   selector:     k8s-app: kubernetes-dashboard   type: NodePort ... $ kubectl apply -f recommended.yaml $ kubectl get pods -n kubernetes-dashboard NAME                                         READY   STATUS    RESTARTS   AGE dashboard-metrics-scraper-6b4884c9d5-gl8nr   1/1     Running   0          13m kubernetes-dashboard-7f99b75bf4-89cds        1/1     Running   0          13m

　　

访问地址：https://NodeIP:30001

创建service account并绑定默认cluster-admin管理员集群角色：

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# 创建用户 $ kubectl create serviceaccount dashboard-admin -n kube-system # 用户授权 $ kubectl create clusterrolebinding dashboard-admin --clusterrole=cluster-admin --serviceaccount=kube-system:dashboard-admin # 获取用户Token $ kubectl describe secrets -n kube-system $(kubectl -n kube-system get secret | awk '/dashboard-admin/{print $1}')

　　使用输出的token登录Dashboard。

 

 

 

9. 遇到的问题

calico插件启动后，发现pod之间网络无法通讯，查看calico的pod不为ready状态：

 

 

 经查看日志：

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1	Readiness probe failed: caliconode is not ready: BIRD is not ready: BGP not established with 10.11.99.144.

　　BGP无法建立连接。

解决方法：指定出口网卡。

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/* 调整calicao 网络插件的网卡发现机制，修改IP_AUTODETECTION_METHOD对应的value值。官方提供的yaml文件中，ip识别策略（IPDETECTMETHOD）没有配置，即默认为first-found，这会导致一个网络异常的ip作为nodeIP被注册，<br>从而影响node-to-node mesh。我们可以修改成can-reach或者interface的策略，尝试连接某一个Ready的node的IP，以此选择出正确的IP。 */   // calico.yaml 文件添加以下二行            - name: IP_AUTODETECTION_METHOD               value: "interface=eth0"     // 配置如下                        # Cluster type to identify the deployment type             - name: CLUSTER_TYPE               value: "k8s,bgp"             # Specify interface             - name: IP_AUTODETECTION_METHOD               value: "interface=eth0"             # Auto-detect the BGP IP address.             - name: IP               value: "autodetect"             # Enable IPIP             - name: CALICO_IPV4POOL_IPIP               value: "Always"             # Enable or Disable VXLAN on the default IP pool.             - name: CALICO_IPV4POOL_VXLAN               value: "Never"

　　

修改参数后，重建pod，恢复正常：