shell - 安装kubernetes - 《Linux模块》

yum install -y kubelet-1.20.11 kubeadm-1.20.11 kubectl-1.20.11
systemctl enable kubelet && systemctl start kubelet

containerd —version
# kubelet —version

初始化master节点

创建初始化配置文件
可使用如下命令生成初始化配置文件

[root@k8s-master01 ~]# kubeadm config print init-defaults > kubeadm-config.yaml
W1202 10:03:02.944058    4055 kubelet.go:200] cannot automatically set CgroupDriver when starting the Kubelet: cannot execute 'docker info -f {{.CgroupDriver}}': executable file not found in $PATH

这个错误好像是没有用docker的原因，具体没找到原因，暂时先忽略
查看配置文件

[root@k8s-master01 ~]# cat kubeadm-config.yaml 
apiVersion: kubeadm.k8s.io/v1beta2
bootstrapTokens:
- groups:
  - system:bootstrappers:kubeadm:default-node-token
  token: abcdef.0123456789abcdef
  ttl: 24h0m0s
  usages:
  - signing
  - authentication
kind: InitConfiguration
localAPIEndpoint:
  advertiseAddress: 192.168.117.121   ////集群vip的地址，暂时用master节点IP
  bindPort: 6443
nodeRegistration:
  criSocket: /run/containerd/containerd.sock   ////默认是docker，改成containerd的sock地址
  name: k8s-master01
  taints:
  - effect: NoSchedule
    key: node-role.kubernetes.io/master
---
apiServer:
  timeoutForControlPlane: 4m0s
apiVersion: kubeadm.k8s.io/v1beta2
certificatesDir: /etc/kubernetes/pki
clusterName: kubernetes
controllerManager: {}
dns:
  type: CoreDNS
etcd:
  local:
    dataDir: /var/lib/etcd
imageRepository: registry.aliyuncs.com/google_containers   ////改成阿里的镜像地址
kind: ClusterConfiguration
kubernetesVersion: v1.20.11
networking:
  dnsDomain: cluster.local
  podSubnet: "10.244.0.0/16"
  serviceSubnet: 10.96.0.0/12
scheduler: {}
--- 
apiVersion: kubeproxy.config.k8s.io/v1alpha1  ////添加kubeproxy的配置，默认mode为iptables，改成ipvs
kind: KubeProxyConfiguration 
mode: ipvs 
--- 
apiVersion: kubelet.config.k8s.io/v1beta1   ////增加kubelet的配置，cgroupDriver改成systemd(官方推荐用systemd)
kind: KubeletConfiguration 
cgroupDriver: systemd
kubeReserved:
  cpu: "200m"
  memory: "200Mi"
  ephemeral-storage: "2Gi"
systemReserved:
  cpu: "200m"
  memory: "200Mi"
  ephemeral-storage: "1Gi"
evictionHard:                        ////增加资源的配置
  memory.available: "500Mi"
  nodefs.available: "10%"

配置说明：

controlPlaneEndpoint：为vip地址和haproxy监听端口6444
imageRepository:由于国内无法访问google镜像仓库k8s.gcr.io，这里指定为阿里云镜像仓库registry.aliyuncs.com/google_containers
podSubnet:指定的IP地址段与后续部署的网络插件相匹配，这里需要部署flannel插件，所以配置为10.244.0.0/16
mode: ipvs:最后追加的配置为开启ipvs模式。
在集群搭建完成后可以使用如下命令查看生效的配置文件：

kubectl -n kube-system get cm kubeadm-config -oyaml

初始化Master01节点

这里追加tee命令将初始化日志输出到kubeadm-init.log中以备用（可选）。

[root@k8s-master01 ~]# kubeadm init --config=kubeadm-config.yaml --upload-certs | tee kubeadm-init.log             
[init] Using Kubernetes version: v1.20.11
[preflight] Running pre-flight checks
error execution phase preflight: [preflight] Some fatal errors occurred:
        [ERROR NumCPU]: the number of available CPUs 1 is less than the required 2
        [ERROR Mem]: the system RAM (972 MB) is less than the minimum 1700 MB
[preflight] If you know what you are doing, you can make a check non-fatal with `--ignore-preflight-errors=...`
To see the stack trace of this error execute with --v=5 or higher

该命令指定了初始化时需要使用的配置文件，其中添加—upload-certs参数可以在后续执行加入节点时自动分发证书文件。节点的cpu和内存要大于2核2G。
初始化示例


[root@k8s-master01 ~]# kubeadm init --config=kubeadm-config.yaml --upload-certs | tee kubeadm-init.log
[init] Using Kubernetes version: v1.20.11
[preflight] Running pre-flight checks
[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-master01 kubernetes kubernetes.default kubernetes.default.svc kubernetes.default.svc.cluster.local] and IPs [10.96.0.1 192.168.117.121]
[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-master01 localhost] and IPs [192.168.117.121 127.0.0.1 ::1]
[certs] Generating "etcd/peer" certificate and key
[certs] etcd/peer serving cert is signed for DNS names [k8s-master01 localhost] and IPs [192.168.117.121 127.0.0.1 ::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 15.003537 seconds
[upload-config] Storing the configuration used in ConfigMap "kubeadm-config" in the "kube-system" Namespace
[kubelet] Creating a ConfigMap "kubelet-config-1.20" in namespace kube-system with the configuration for the kubelets in the cluster
[upload-certs] Storing the certificates in Secret "kubeadm-certs" in the "kube-system" Namespace
[upload-certs] Using certificate key:
d6083fa656f99e7dd2a9423c471016920c44db13f13632bfef90b0e52cfc0bce
[mark-control-plane] Marking the node k8s-master01 as control-plane by adding the labels "node-role.kubernetes.io/master=''" and "node-role.kubernetes.io/control-plane='' (deprecated)"
[mark-control-plane] Marking the node k8s-master01 as control-plane by adding the taints [node-role.kubernetes.io/master:NoSchedule]
[bootstrap-token] Using token: abcdef.0123456789abcdef
[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

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 192.168.117.121:6443 --token abcdef.0123456789abcdef \
    --discovery-token-ca-cert-hash sha256:3081167c6ff9370d23a3e435a4727424675f69162f88fe31e9e42931a94f27a0

kubeadm init主要执行了以下操作：

[init]：指定版本进行初始化操作
[preflight] ：初始化前的检查和下载所需要的Docker镜像文件
[kubelet-start]：生成kubelet的配置文件”/var/lib/kubelet/config.yaml”，没有这个文件kubelet无法启动，所以初始化之前的kubelet实际上启动失败。
[certificates]：生成Kubernetes使用的证书，存放在/etc/kubernetes/pki目录中。
[kubeconfig] ：生成 KubeConfig 文件，存放在/etc/kubernetes目录中，组件之间通信需要使用对应文件。
[control-plane]：使用/etc/kubernetes/manifest目录下的YAML文件，安装 Master 组件。
[etcd]：使用/etc/kubernetes/manifest/etcd.yaml安装Etcd服务。
[wait-control-plane]：等待control-plan部署的Master组件启动。
[apiclient]：检查Master组件服务状态。
[uploadconfig]：更新配置
[kubelet]：使用configMap配置kubelet。
[patchnode]：更新CNI信息到Node上，通过注释的方式记录。
[mark-control-plane]：为当前节点打标签，打了角色Master，和不可调度标签，这样默认就不会使用Master节点来运行Pod。
[bootstrap-token]：生成token记录下来，后边使用kubeadm join往集群中添加节点时会用到
[addons]：安装附加组件CoreDNS和kube-proxy
说明：无论是初始化失败或者集群已经完全搭建成功，你都可以直接执行kubeadm reset命令清理集群或节点，然后重新执行kubeadm init或kubeadm join相关操作即可。

无论在master节点或node节点，要能够执行kubectl命令必须进行以下配置：
root用户执行以下命令

cat << EOF >> ~/.bashrc
export KUBECONFIG=/etc/kubernetes/admin.conf
EOF
source ~/.bashrc

普通用户执行以下命令（参考init时的输出结果）

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

等集群配置完成后，可以在所有master节点和node节点进行以上配置，以支持kubectl命令。针对node节点复制任意master节点/etc/kubernetes/admin.conf到本地。

# export MASTER_IP=10.0.13.127
# export APISERVER_NAME=apiserver.carobo.cn
# export POD_SUBNET=172.31.0.0/16
# echo "${MASTER_IP}    ${APISERVER_NAME}" >> /etc/hosts
# echo $MASTER_IP $APISERVER_NAME $POD_SUBNET

# cat init_master.sh 
#!/bin/bash
# 只在 master 节点执行
# 脚本出错时终止执行
set -e

if [ ${#POD_SUBNET} -eq 0 ] || [ ${#APISERVER_NAME} -eq 0 ]; then
  echo -e "\033[31;1m请确保您已经设置了环境变量 POD_SUBNET 和 APISERVER_NAME \033[0m"
  echo 当前POD_SUBNET=$POD_SUBNET
  echo 当前APISERVER_NAME=$APISERVER_NAME
  exit 1
fi

# 查看完整配置选项 https://godoc.org/k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm/v1beta2
rm -f ./kubeadm-config.yaml
cat <<EOF > ./kubeadm-config.yaml
---
apiVersion: kubeadm.k8s.io/v1beta2
kind: ClusterConfiguration
kubernetesVersion: v1.20.11
imageRepository: registry.aliyuncs.com/k8sxio
controlPlaneEndpoint: "${APISERVER_NAME}:6443"
networking:
  serviceSubnet: "10.96.0.0/16"
  podSubnet: "${POD_SUBNET}"
  dnsDomain: "cluster.local"
dns:
  type: CoreDNS
  imageRepository: swr.cn-east-2.myhuaweicloud.com/coredns
  imageTag: 1.8.0

---
apiVersion: kubelet.config.k8s.io/v1beta1
kind: KubeletConfiguration
cgroupDriver: systemd
EOF

# kubeadm init
# 根据您服务器网速的情况，您需要等候 3 - 10 分钟
echo ""
echo "抓取镜像，请稍候..."
kubeadm config images pull --config=kubeadm-config.yaml
echo ""
echo "初始化 Master 节点"
kubeadm init --config=kubeadm-config.yaml --upload-certs