K8s-master生成 ssh 密钥，分发公钥到各节点：
# 生成 ssh 密钥，直接一路回车
ssh-keygen -t rsa
# 复制刚刚生成的密钥到各节点可信列表中，需分别输入各主机密码
ssh-copy-id root@k8s-master
ssh-copy-id root@k8s-node1
ssh-copy-id root@k8s-node2
ssh-copy-id root@k8s-node3
禁用 swap
swap 仅当内存不够时会使用硬盘块充当额外内存，硬盘的IO较内存差距极大，禁用swap以提供性能，各节点均需执行：
swapoff -a
sed -i 's/.*swap.*/#&/' /etc/fstab
关闭 SELinux
关闭SELinux，否则kubelet 挂载目录时可能报错 Permission denied，可以设置为permissive或disabled，permissive会提示warn信息 ，各节点均需执行：
setenforce 0
sed -i 's/^SELINUX=.*/SELINUX=disabled/' /etc/selinux/config
设置系统时区、同步时间
timedatectl set-timezone Asia/Shanghai
systemctl enable --now chronyd
# 查看同步状态, 输出
[root@ecs-2aae ~]# timedatectl status
Local time: Sun 2020-12-27 21:59:02 CST
Universal time: Sun 2020-12-27 13:59:02 UTC
RTC time: Sun 2020-12-27 13:58:31
Time zone: Asia/Shanghai (CST, +0800)
System clock synchronized: yes
NTP service: active
RTC in local TZ: no
[root@ecs-2aae ~]#
##
# systemctl clok synchronronize: yes 表示时钟已同步
# NTP service: active 表示开启了时钟同步服务
#############################################################
# 将当前的 UTC 时间写入硬件时钟
timedatectl set-local-rtc 0
# 重启依赖于系统时间的服务器
systemctl restart rsyslog && systemctl restart crond
部署Docker
所有节点均需安装部署 docker， 可参见《CentOS8 安装docker》
部署Kubernetes集群
无特殊说明，各节点均需执行如下步骤
添加kubernetes 源
cat < /etc/yum.repos.d/kubernetes.repo
[kubernetes]
name=Kubernetes
baseurl=https://mirrors.aliyun.com/kubernetes/yum/repos/kubernetes-el7-x86_64
enabled=1
gpgcheck=0
repo_gpgcheck=0
EOF
安装kubeadm、kubelet、kubectl
各节点均需安装 kubeadm、kubelet，kubectl仅 k8s-master 节点续约安装（作为 worker 节点， kubectl 无法使用， 可以不装）
yum install -y kubelet kubeadm kubectl --disableexcludes=kubernetes
systemctl enable --now kubelet
配置自动补全命令
#安装bash自动补全插件
yum install bash-completion -y
#设置kubectl与kubeadm命令补全，下次login生效
kubectl completion bash > /etc/bash_completion.d/kubectl
kubeadm completion bash > /etc/bash_completion.d/kubeadm
预拉取kubernetes镜像 （第一种方式）
由于国内网络因素，kubernetes镜像需要从mirrors站点或通过dockerhub用户推送的镜像拉取：
#查看指定k8s版本需要哪些镜像
[root@ecs-2aae ~]# kubeadm config images list
k8s.gcr.io/kube-apiserver:v1.20.1
k8s.gcr.io/kube-controller-manager:v1.20.1
k8s.gcr.io/kube-scheduler:v1.20.1
k8s.gcr.io/kube-proxy:v1.20.1
k8s.gcr.io/pause:3.2
k8s.gcr.io/etcd:3.4.13-0
k8s.gcr.io/coreDNS:1.7.0
[root@ecs-2aae ~]#
在 /opt/soft/kuberetes 目录下，新建脚本pull-k8s-images.sh，内容如下：
#!/bin/bash
# Script For Quick Pull K8S Docker Images
# by WUXH
KUBE_VERSION=v1.20.1
PAUSE_VERSION=3.2
CORE_DNS_VERSION=1.7.0
ETCD_VERSION=3.4.13-0
# pull kubernetes images from hub.docker.com
docker pull kubeimage/kube-proxy:$KUBE_VERSION
docker pull kubeimage/kube-controller-manager:$KUBE_VERSION
docker pull kubeimage/kube-apiserver:$KUBE_VERSION
docker pull kubeimage/kube-scheduler:$KUBE_VERSION
# pull aliyuncs mirror docker images
docker pull registry.cn-hangzhou.aliyuncs.com/google_containers/pause:$PAUSE_VERSION
docker pull registry.cn-hangzhou.aliyuncs.com/google_containers/coredns:$CORE_DNS_VERSION
docker pull registry.cn-hangzhou.aliyuncs.com/google_containers/etcd:$ETCD_VERSION
# retag to k8s.gcr.io prefix
docker tag kubeimage/kube-proxy:$KUBE_VERSION k8s.gcr.io/kube-proxy:$KUBE_VERSION
docker tag kubeimage/kube-controller-manager:$KUBE_VERSION k8s.gcr.io/kube-controller-manager:$KUBE_VERSION
docker tag kubeimage/kube-apiserver:$KUBE_VERSION k8s.gcr.io/kube-apiserver:$KUBE_VERSION
docker tag kubeimage/kube-scheduler:$KUBE_VERSION k8s.gcr.io/kube-scheduler:$KUBE_VERSION
docker tag registry.cn-hangzhou.aliyuncs.com/google_containers/pause:$PAUSE_VERSION k8s.gcr.io/pause:$PAUSE_VERSION
docker tag registry.cn-hangzhou.aliyuncs.com/google_containers/coredns:$CORE_DNS_VERSION k8s.gcr.io/coredns:$CORE_DNS_VERSION
docker tag registry.cn-hangzhou.aliyuncs.com/google_containers/etcd:$ETCD_VERSION k8s.gcr.io/etcd:$ETCD_VERSION
# untag origin tag, the images won't be delete.
docker rmi kubeimage/kube-proxy:$KUBE_VERSION
docker rmi kubeimage/kube-controller-manager:$KUBE_VERSION
docker rmi kubeimage/kube-apiserver:$KUBE_VERSION
docker rmi kubeimage/kube-scheduler:$KUBE_VERSION
docker rmi registry.cn-hangzhou.aliyuncs.com/google_containers/pause:$PAUSE_VERSION
docker rmi registry.cn-hangzhou.aliyuncs.com/google_containers/coredns:$CORE_DNS_VERSION
docker rmi registry.cn-hangzhou.aliyuncs.com/google_containers/etcd:$ETCD_VERSION
脚本添加可执行权限，执行脚本拉取镜像：
chmod +x pull-k8s-images.sh
./opt/soft/kuberetes/pull-k8s-images.sh
拉取完成，执行 docker images 查看镜像：
kubernetes初始化指定镜像 （第二种方式）
kubeadm init --image-repository=registry.aliyuncs.com/google_containers --kubernetes-version=v1.20.1 --pod-network-cidr 10.244.0.0/16
输出如下：
[root@ecs-2aae ~]# kubeadm init --image-repository=registry.aliyuncs.com/google_containers --pod-network-cidr=10.244.0.0/16 --kubernetes-version=v1.20.1
[init] Using Kubernetes version: v1.20.1
[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 FileExisting-tc]: tc not found in system path
[WARNING SystemVerification]: this Docker version is not on the list of validated versions: 20.10.1. 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 [ecs-2aae kubernetes kubernetes.default kubernetes.default.svc kubernetes.default.svc.cluster.local] and IPs [10.96.0.1 192.168.1.61]
[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 [ecs-2aae localhost] and IPs [192.168.1.61 127.0.0.1 ::1]
[certs] Generating "etcd/peer" certificate and key
[certs] etcd/peer serving cert is signed for DNS names [ecs-2aae localhost] and IPs [192.168.1.61 127.0.0.1 ::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 7.501971 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] Skipping phase. Please see --upload-certs
[mark-control-plane] Marking the node ecs-2aae 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 ecs-2aae as control-plane by adding the taints [node-role.kubernetes.io/master:NoSchedule]
[bootstrap-token] Using token: xksx1a.t09ok8h7w6ixnyva
[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 192.168.1.61:6443 --token 379rcy.4k2gsoggyjxzo4u9 \
--discovery-token-ca-cert-hash sha256:a8f563cd1c742fa64eef6db0420401ecb57556281199989449f872da9f50609f
[root@ecs-2aae ~]#
可能故障
故障1：k8s node节点加入集群报错[WARNING IsDockerSystemdCheck]: detected “cgroupfs“ as the Docker cgroup driver.
# 解决
cat < /etc/docker/daemon.json
{
"exec-opts": ["native.cgroupdriver=systemd"]
}
EOF
#重启docker
systemctl restart docker
为日常使用集群的用户添加kubectl使用权限，配置master认证
[root@ecs-2aae ~]# mkdir -p ~/.kube
[root@ecs-2aae ~]# cp -i /etc/kubernetes/admin.conf ~/.kube/admin.conf
[root@ecs-2aae ~]# chown $(id -u):$(id -g) ~/.kube/admin.conf
[root@ecs-2aae ~]# echo 'export KUBECONFIG=/etc/kubernetes/admin.conf' >> /etc/profile
[root@ecs-2aae ~]# . /etc/profile
安装网络组件，以flannel为例
[root@k8s-master ~]# kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.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
[root@k8s-master ~]#
Node节点加入集群
这句话其实就是Master节点执行kubeadm init成功之后输出的最后一句话，我们拿到Node节点中直接执行即可
kubeadm join 192.168.1.61:6443 --token 379rcy.4k2gsoggyjxzo4u9 \
--discovery-token-ca-cert-hash sha256:a8f563cd1c742fa64eef6db0420401ecb57556281199989449f872da9f50609f
输出：
[root@k8s-node1 ~]# kubeadm join 192.168.1.61:6443 --token 379rcy.4k2gsoggyjxzo4u9 --discovery-token-ca-cert-hash sha256:a8f563cd1c742fa64eef6db0420401ecb57556281199989449f872da9f50609f
[preflight] Running pre-flight checks
[WARNING FileExisting-tc]: tc not found in system path
[WARNING SystemVerification]: this Docker version is not on the list of validated versions: 20.10.1. Latest validated version: 19.03
[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: ### 节点加入成功啦
* 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.
[root@k8s-node1 ~]#
查看集群节点状态
[root@k8s-master ~]# kubectl get nodes
NAME STATUS ROLES AGE VERSION
k8s-master Ready control-plane,master 67m v1.20.1
k8s-node1 Ready 40m v1.20.1
k8s-node2 Ready 32m v1.20.1
k8s-node3 Ready 30m v1.20.1
[root@k8s-master ~]#
⚠： 如果节点是 NoReady 状态，可以稍微等一会儿，集群节点会自动拉起 flannel 镜像，由于网络可能稍慢！！
到此，关于“kubernetes环境的搭建步骤”的学习就结束了，希望能够解决大家的疑惑。理论与实践的搭配能更好的帮助大家学习，快去试试吧！若想继续学习更多相关知识，请继续关注创新互联网站，小编会继续努力为大家带来更多实用的文章！
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