• Kubernetes安装篇（二）：基于Kubeadm方式的集群部署

在实际生产环境中，Kubernetes 环境就比这复杂的多，起码也是集群起步，因此，本文将从生产环境出发，为你带来基于生产环境下的 Kubernetes 集群部署，让你真正懂得该如何部署真正的 Kubernetes 集群环境。

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上一篇文章《Kubernetes安装篇（上）：基于Minikube方式部署本地环境》介绍了基于本地环境下的 Kubernetes 安装，目的在于搭建本地开发环境。但在实际生产环境中，Kubernetes 环境就比这复杂的多，起码也是集群起步，因此，本文将从生产环境出发，为你带来基于生产环境下的 Kubernetes 集群部署，让你真正懂得该如何部署真正的 Kubernetes 集群环境。

1、环境准备

采用 VMware 虚拟机安装 Kubernetes 集群，准备环境情况如下：

  • 2 台虚拟机：CentOS 7，配置越高越好！
  • Docker Version：19.03.13
  • kubeadm Version：V1.20.0

2、系统初始化

在安装之前，一些系统参数、配置需统一配置，确保后续安装的顺利进行。

系统初始化部分，均需在 Master、Node 节点上执行。

2.1 设置系统主机名

hostnamectl set-hostname <hostname>

执行过程：

  • Master 节点
[root@localhost xcbeyond]# hostnamectl set-hostname k8s-master
  • Node 节点：
[root@localhost xcbeyond]# hostnamectl set-hostname k8s-node01

2.2 修改 host 文件

为了方便集群间各节点间可以直接通过主机名互通，因此建议修改 host 文件。

在 Master、Node 节点上分别修改 host 文件 /etc/hosts，添加以下内容：

192.168.11.100 k8s-master
192.168.11.101 k8s-node01

上述 IP 是对应节点的实际 IP。

2.3 安装依赖包

在接下来 Kubernetes 使用过程中，可能涉及一些工具，事先安装便于后期使用。

yum install -y conntrack ntpdate ntp ipvsadm ipset jq iptables curl sysstat libseccomp net-tools

2.4 设置防火墙为 Iptables 并设置空规则

systemctl  stop firewalld  &&  systemctl  disable firewalld

yum -y install iptables-services  &&  systemctl  start iptables  &&  systemctl  enable iptables&&  iptables -F  &&  service iptables save

2.5 关闭 SELINUX

swapoff -a && sed -i '/ swap / s/^\(.*\)$/#\1/g' /etc/fstab

# 将SELinux禁用
setenforce 0 && sed -i 's/^SELINUX=.*/SELINUX=disabled/' /etc/selinux/config

2.6 调整内核参数

cat > kubernetes.conf <<EOF
net.bridge.bridge-nf-call-iptables=1	# 节点上的iptables能够正确地查看桥接流量
net.bridge.bridge-nf-call-ip6tables=1	# 节点上的iptables能够正确地查看桥接流量
net.ipv4.ip_forward=1
net.ipv4.tcp_tw_recycle=0
vm.swappiness=0 		# 禁止使用 swap 空间，只有当系统 OOM 时才允许使用它
vm.overcommit_memory=1  # 不检查物理内存是否够用
vm.panic_on_oom=0 		# 开启 OOM
fs.inotify.max_user_instances=8192
fs.inotify.max_user_watches=1048576
fs.file-max=52706963
fs.nr_open=52706963
net.ipv6.conf.all.disable_ipv6=1
net.netfilter.nf_conntrack_max=2310720
EOF

cp kubernetes.conf  /etc/sysctl.d/kubernetes.conf

sysctl -p /etc/sysctl.d/kubernetes.conf

2.7 调整时区

(如果时区正确，则无需调整)

# 设置系统时区为中国/上海
timedatectl set-timezone Asia/Shanghai

# 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
systemctl restart rsyslog
systemctl restart crond

2.8 升级系统内核为 5.4

CentOS 7.x 系统自带的 3.10.x 内核存在一些Bugs，导致运行的 Docker、Kubernetes 不稳定，例如： rpm -Uvh http://www.elrepo.org/elrepo-release-7.0-3.el7.elrepo.noarch.rpm

rpm -Uvh http://www.elrepo.org/elrepo-release-7.0-3.el7.elrepo.noarch.rpm

# 安装完成后检查/boot/grub2/grub.cfg中对应内核menuentry中是否包含initrd16配置，如果没有，再安装一次！
yum --enablerepo=elrepo-kernel install -y kernel-lt

# 设置开机从新内核启动
grub2-set-default 'CentOS Linux (5.4.93-1.el7.elrepo.x86_64) 7 (Core)'

执行过程：

[root@k8s-master xcbeyond]# uname -r
3.10.0-1127.19.1.el7.x86_64
[root@k8s-master xcbeyond]# rpm -Uvh http://www.elrepo.org/elrepo-release-7.0-3.el7.elrepo.noarch.rpm
获取http://www.elrepo.org/elrepo-release-7.0-3.el7.elrepo.noarch.rpm
警告：/var/tmp/rpm-tmp.xF145X: 头V4 DSA/SHA1 Signature, 密钥 ID baadae52: NOKEY
准备中...                          ################################# [100%]
正在升级/安装...
   1:elrepo-release-7.0-3.el7.elrepo  ################################# [100%]
[root@k8s-master xcbeyond]# yum --enablerepo=elrepo-kernel install -y kernel-lt
已加载插件：fastestmirror, langpacks
Loading mirror speeds from cached hostfile
 ……
警告：RPM 数据库已被非 yum 程序修改。
  正在安装    : kernel-lt-5.4.93-1.el7.elrepo.x86_64     1/1 
  验证中      : kernel-lt-5.4.93-1.el7.elrepo.x86_64     1/1 

已安装:
  kernel-lt.x86_64 0:5.4.93-1.el7.elrepo

完毕！
[root@k8s-master xcbeyond]# grub2-set-default 'CentOS Linux (5.4.93-1.el7.elrepo.x86_64) 7 (Core)'
[root@k8s-master xcbeyond]# reboot

重启完成后，查看系统内核已升级成功：

[xcbeyond@k8s-master ~]$ uname -r
5.4.93-1.el7.elrepo.x86_64

别忘了在 node 节点上执行！

2.9 kube-proxy 开启 ipvs 的前置条件

modprobe br_netfilter

cat > /etc/sysconfig/modules/ipvs.modules <<EOF
#!/bin/bash
modprobe -- ip_vs
modprobe -- ip_vs_rr
modprobe -- ip_vs_wrr
modprobe -- ip_vs_sh
modprobe -- nf_conntrack_ipv4
EOF

chmod 755 /etc/sysconfig/modules/ipvs.modules && bash /etc/sysconfig/modules/ipvs.modules && lsmod | grep -e ip_vs -e nf_conntrack_ipv4

执行过程：

[root@k8s-master xcbeyond]# modprobe br_netfilter
[root@k8s-master xcbeyond]# cat > /etc/sysconfig/modules/ipvs.modules <<EOF
> #!/bin/bash
> modprobe -- ip_vs
> modprobe -- ip_vs_rr
> modprobe -- ip_vs_wrr
> modprobe -- ip_vs_sh
> modprobe -- nf_conntrack_ipv4
> EOF
[root@k8s-master xcbeyond]# chmod 755 /etc/sysconfig/modules/ipvs.modules && bash /etc/sysconfig/modules/ipvs.modules && lsmod | grep -e ip_vs -e nf_conntrack_ipv4
modprobe: FATAL: Module nf_conntrack_ipv4 not found.

别忘了在 Node 节点上执行！

3、Docker 安装

此处不再讲述 Docker 安装的过程，具体可参考之前写的文章。

4、安装 kubeadm

4.1 安装 kubeadm、kubectl 和 kubelet

需要在每台机器上（Master、Node 节点）安装以下的软件包：

  • kubeadm：用来初始化集群的指令。
  • kubectl：用来与集群通信的命令行工具。
  • kubelet：在集群中的每个节点上用来启动 Pod 和容器等。

（1）配置Kubernetes数据源

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

执行过程：

[root@k8s-master xcbeyond]# cat <<EOF > /etc/yum.repos.d/kubernetes.repo
> [kubernetes]
> name=Kubernetes
> baseurl=http://mirrors.aliyun.com/kubernetes/yum/repos/kubernetes-el7-x86_64
> enabled=1
> gpgcheck=0
> repo_gpgcheck=0
> gpgkey=http://mirrors.aliyun.com/kubernetes/yum/doc/yum-key.gpg
> http://mirrors.aliyun.com/kubernetes/yum/doc/rpm-package-key.gpg
> EOF

（2）安装 kubeadm、kubectl、kubelet

yum -y  install  kubeadm kubectl kubelet

执行过程：

[root@k8s-master xcbeyond]# yum -y  install  kubeadm kubectl kubelet
已加载插件：fastestmirror, langpacks
Loading mirror speeds from cached hostfile
 * base: mirrors.neusoft.edu.cn
 * elrepo: mirrors.neusoft.edu.cn
 * extras: mirrors.neusoft.edu.cn
 * updates: mirrors.neusoft.edu.cn
kubernetes                                                       | 1.4 kB  00:00:00     
正在解决依赖关系
--> 正在检查事务
---> 软件包 kubeadm.x86_64.0.1.20.2-0 将被 安装
--> 正在处理依赖关系 kubernetes-cni >= 0.8.6，它被软件包 kubeadm-1.20.2-0.x86_64 需要
--> 正在处理依赖关系 cri-tools >= 1.13.0，它被软件包 kubeadm-1.20.2-0.x86_64 需要
---> 软件包 kubectl.x86_64.0.1.20.2-0 将被 安装
---> 软件包 kubelet.x86_64.0.1.20.2-0 将被 安装
--> 正在处理依赖关系 socat，它被软件包 kubelet-1.20.2-0.x86_64 需要
--> 正在检查事务
---> 软件包 cri-tools.x86_64.0.1.13.0-0 将被 安装
---> 软件包 kubernetes-cni.x86_64.0.0.8.7-0 将被 安装
---> 软件包 socat.x86_64.0.1.7.3.2-2.el7 将被 安装
--> 解决依赖关系完成

依赖关系解决

=========================================================================================
 Package           架构            版本            源        		   大小
=========================================================================================
正在安装:
 kubeadm           x86_64         1.20.2-0        kubernetes          8.3 M
 kubectl           x86_64         1.20.2-0        kubernetes          8.5 M
 kubelet           x86_64         1.20.2-0        kubernetes          20 M
为依赖而安装:
 cri-tools         x86_64         1.13.0-0        kubernetes          5.1 M
 kubernetes-cni    x86_64         0.8.7-0         kubernetes          19 M
 socat             x86_64         1.7.3.2-2.el7   base                290 k

事务概要
=========================================================================================
安装  3 软件包 (+3 依赖软件包)

总计：61 M
总下载量：52 M
安装大小：262 M
Downloading packages:
(1/5): 14bfe6e75a9efc8eca3f638eb22c7e2ce759c67f95b43b16fae4ebabde1549f3-cri-tools-1.13.0-0.x86_64.rpm                                                                   | 5.1 MB  00:00:03     
(2/5): b46459afb07aaf12937f7f310b876fab9f5f904eaa8f4a88a21547477eafba78-kubeadm-1.20.2-0.x86_64.rpm                                                                     | 8.3 MB  00:00:06     
(3/5): socat-1.7.3.2-2.el7.x86_64.rpm                                                                                                                                   | 290 kB  00:00:02     
(4/5): a79d632b1f8c40d2a00e2f98cba68b55c3928d70b97c32aad61c10e17965c2f1-kubelet-1.20.2-0.x86_64.rpm                                                                     |  20 MB  00:00:14     
(5/5): db7cb5cb0b3f6875f54d10f02e625573988e3e91fd4fc5eef0b1876bb18604ad-kubernetes-cni-0.8.7-0.x86_64.rpm                                                               |  19 MB  00:00:11     
-----------------------------------------------------------------------------------------
总计                                                                                                                                                           2.8 MB/s |  52 MB  00:00:18     
Running transaction check
Running transaction test
Transaction test succeeded
Running transaction
  正在安装    : socat-1.7.3.2-2.el7.x86_64                     1/6 
  正在安装    : kubelet-1.20.2-0.x86_64                        2/6 
  正在安装    : kubernetes-cni-0.8.7-0.x86_64                  3/6 
  正在安装    : kubectl-1.20.2-0.x86_64                        4/6 
  正在安装    : cri-tools-1.13.0-0.x86_64                      5/6 
  正在安装    : kubeadm-1.20.2-0.x86_64                        6/6 
  验证中      : kubernetes-cni-0.8.7-0.x86_64                  1/6 
  验证中      : kubelet-1.20.2-0.x86_64                        2/6 
  验证中      : kubeadm-1.20.2-0.x86_64                        3/6 
  验证中      : cri-tools-1.13.0-0.x86_64                      4/6 
  验证中      : kubectl-1.20.2-0.x86_64                        5/6 
  验证中      : socat-1.7.3.2-2.el7.x86_64                     6/6 

已安装:
  kubeadm.x86_64 0:1.20.2-0    kubectl.x86_64 0:1.20.2-0    kubelet.x86_64 0:1.20.2-0     
  
作为依赖被安装:
  cri-tools.x86_64 0:1.13.0-0  kubernetes-cni.x86_64 0:0.8.7-0  socat.x86_64 0:1.7.3.2-2.el7                                 

完毕！

（3）设置开机启动 kubelet

systemctl enable kubelet.service

执行过程：

[root@k8s-master xcbeyond]# systemctl enable kubelet.service
Created symlink from /etc/systemd/system/multi-user.target.wants/kubelet.service to /usr/lib/systemd/system/kubelet.service.

别忘了在 Node 节点上执行！

4.2 创建集群

4.2.1 安装镜像拉取

kubeadm 创建集群默认使用的 docker 镜像仓库为 k8s.gcr.io，而国内无法直接访问，需要中转才能使用。

（已将所需镜像构建发布在 docker hub上，方便国内直接使用）

Master、Node 节点都需要执行！

安装镜像拉取脚本k8s-images-pull.sh如下：

#!/bin/bash

kubernetes_version="v1.20.0"

# 下载需要的镜像(docker hub)
kubeadm config images list --kubernetes-version=${kubernetes_version} |sed -e 's/^/docker pull /g' -e 's#k8s.gcr.io#xcbeyond#g' |sh -x

# 重命名镜像
docker images |grep xcbeyond |awk '{print "docker tag ",$1":"$2,$1":"$2}' |sed -e 's#xcbeyond#k8s.gcr.io#2' |sh -x

# 删除xcbeyond镜像
docker images |grep xcbeyond |awk '{print "docker rmi ", $1":"$2}' |sh -x

查看需要哪些镜像：kubeadm config images list

执行过程如下：

[root@k8s-master xcbeyond]# ./k8s-images-pull.sh 
+ docker pull xcbeyond/kube-apiserver:v1.20.0
v1.20.0: Pulling from xcbeyond/kube-apiserver
f398b465657e: Pull complete 
cbcdf8ef32b4: Pull complete 
a9b56b1d4e55: Pull complete 
Digest: sha256:c54e33e290aa1463eae80f6bd4440af3def87f01f86a37a12ec213eb205e538a
Status: Downloaded newer image for xcbeyond/kube-apiserver:v1.20.0
docker.io/xcbeyond/kube-apiserver:v1.20.0
+ docker pull xcbeyond/kube-controller-manager:v1.20.0
v1.20.0: Pulling from xcbeyond/kube-controller-manager
f398b465657e: Already exists 
cbcdf8ef32b4: Already exists 
2ffb969cde54: Pull complete 
Digest: sha256:5f6321aaa0d9880bd3a96a0d589fc96e912e30f7f5f6d6f53c406eb2b4b20b68
Status: Downloaded newer image for xcbeyond/kube-controller-manager:v1.20.0
docker.io/xcbeyond/kube-controller-manager:v1.20.0
+ docker pull xcbeyond/kube-scheduler:v1.20.0
v1.20.0: Pulling from xcbeyond/kube-scheduler
f398b465657e: Already exists 
cbcdf8ef32b4: Already exists 
2f71710e6dc2: Pull complete 
Digest: sha256:10f3ae3ed09f92b3be037e1dd465214046135eabd9879db43b3fe7159a1bae1c
Status: Downloaded newer image for xcbeyond/kube-scheduler:v1.20.0
docker.io/xcbeyond/kube-scheduler:v1.20.0
+ docker pull xcbeyond/kube-proxy:v1.20.0
v1.20.0: Pulling from xcbeyond/kube-proxy
e5a8c1ed6cf1: Pull complete 
f275df365c13: Pull complete 
6a2802bb94f4: Pull complete 
cb3853c52da4: Pull complete 
db342cbe4b1c: Pull complete 
9a72dd095a53: Pull complete 
6943e8f5bc84: Pull complete 
Digest: sha256:d583d644b186519597dfdfe420710ab0888927e286ea43b2a6f54ba4329e93e4
Status: Downloaded newer image for xcbeyond/kube-proxy:v1.20.0
docker.io/xcbeyond/kube-proxy:v1.20.0
+ docker pull xcbeyond/pause:3.2
3.2: Pulling from xcbeyond/pause
c74f8866df09: Pull complete 
Digest: sha256:4dcd2075946239537e21adcf4bb300f07eb5c2c8058d699480f2ae62a5cc5085
Status: Downloaded newer image for xcbeyond/pause:3.2
docker.io/xcbeyond/pause:3.2
+ docker pull xcbeyond/etcd:3.4.13-0
3.4.13-0: Pulling from xcbeyond/etcd
4000adbbc3eb: Already exists 
d72167780652: Already exists 
d60490a768b5: Already exists 
4a4b5535d134: Pull complete 
0dac37e8b31a: Pull complete 
Digest: sha256:79d32edd429163b1ae404eeb078c75fc2f63fc3d606e0cd57285c832e8181ea3
Status: Downloaded newer image for xcbeyond/etcd:3.4.13-0
docker.io/xcbeyond/etcd:3.4.13-0
+ docker pull xcbeyond/coredns:1.7.0
1.7.0: Pulling from xcbeyond/coredns
c6568d217a00: Pull complete 
6937ebe10f02: Pull complete 
Digest: sha256:4310e3ed7a0a9b82cfb2d31c6a7c102b8d05fef2b0208072b87dc4ceca3c47bb
Status: Downloaded newer image for xcbeyond/coredns:1.7.0
docker.io/xcbeyond/coredns:1.7.0
+ docker tag xcbeyond/pause:3.2 k8s.gcr.io/pause:3.2
+ docker tag xcbeyond/kube-controller-manager:v1.20.0 k8s.gcr.io/kube-controller-manager:v1.20.0
+ docker tag xcbeyond/coredns:1.7.0 k8s.gcr.io/coredns:1.7.0
+ docker tag xcbeyond/etcd:3.4.13-0 k8s.gcr.io/etcd:3.4.13-0
+ docker tag xcbeyond/kube-proxy:v1.20.0 k8s.gcr.io/kube-proxy:v1.20.0
+ docker tag xcbeyond/kube-scheduler:v1.20.0 k8s.gcr.io/kube-scheduler:v1.20.0
+ docker tag xcbeyond/kube-apiserver:v1.20.0 k8s.gcr.io/kube-apiserver:v1.20.0
+ docker rmi xcbeyond/pause:3.2
Untagged: xcbeyond/pause:3.2
Untagged: xcbeyond/pause@sha256:4dcd2075946239537e21adcf4bb300f07eb5c2c8058d699480f2ae62a5cc5085
+ docker rmi xcbeyond/kube-controller-manager:v1.20.0
Untagged: xcbeyond/kube-controller-manager:v1.20.0
Untagged: xcbeyond/kube-controller-manager@sha256:5f6321aaa0d9880bd3a96a0d589fc96e912e30f7f5f6d6f53c406eb2b4b20b68
+ docker rmi xcbeyond/coredns:1.7.0
Untagged: xcbeyond/coredns:1.7.0
Untagged: xcbeyond/coredns@sha256:4310e3ed7a0a9b82cfb2d31c6a7c102b8d05fef2b0208072b87dc4ceca3c47bb
+ docker rmi xcbeyond/etcd:3.4.13-0
Untagged: xcbeyond/etcd:3.4.13-0
Untagged: xcbeyond/etcd@sha256:79d32edd429163b1ae404eeb078c75fc2f63fc3d606e0cd57285c832e8181ea3
+ docker rmi xcbeyond/kube-proxy:v1.20.0
Untagged: xcbeyond/kube-proxy:v1.20.0
Untagged: xcbeyond/kube-proxy@sha256:d583d644b186519597dfdfe420710ab0888927e286ea43b2a6f54ba4329e93e4
+ docker rmi xcbeyond/kube-scheduler:v1.20.0
Untagged: xcbeyond/kube-scheduler:v1.20.0
Untagged: xcbeyond/kube-scheduler@sha256:10f3ae3ed09f92b3be037e1dd465214046135eabd9879db43b3fe7159a1bae1c
+ docker rmi xcbeyond/kube-apiserver:v1.20.0
Untagged: xcbeyond/kube-apiserver:v1.20.0
Untagged: xcbeyond/kube-apiserver@sha256:c54e33e290aa1463eae80f6bd4440af3def87f01f86a37a12ec213eb205e538a
[root@k8s-master xcbeyond]# docker image ls
REPOSITORY                           TAG                 IMAGE ID            CREATED             SIZE
k8s.gcr.io/pause                     3.2                 b76329639608        16 hours ago        683kB
k8s.gcr.io/kube-controller-manager   v1.20.0             630f45a9961f        16 hours ago        116MB
k8s.gcr.io/coredns                   1.7.0               4e42ad8cda50        21 hours ago        45.2MB
k8s.gcr.io/etcd                      3.4.13-0            999b6137af27        21 hours ago        253MB
k8s.gcr.io/kube-proxy                v1.20.0             51912faaf3a3        21 hours ago        118MB
k8s.gcr.io/kube-scheduler            v1.20.0             62181d1bf9a1        21 hours ago        46.4MB
k8s.gcr.io/kube-apiserver            v1.20.0             0f7e1178e374        22 hours ago        122MB

别忘了在 Node 节点上执行！

4.2.2 初始化主节点

Master 节点是指 Kubernetes 集群中的控制节点，包括 etcd（集群数据库）和 API Server（集群控制的入口进程）。

初始化主节点，执行 kubeadm init <args>。

（1）修改 kubeadm 初始化配置文件。

执行 kubeadm config print init-defaults 命令获取 kubeadm 初始配置文件模板，将其存放在 kubeadm-config.yml：

kubeadm config print init-defaults > kubeadm-config.yml

并修改以下参数：

localAPIEndpoint:
  advertiseAddress: 192.168.66.10		# 主节点实际IP
kubernetesVersion: v1.20.0
networking:
  podSubnet: "10.244.0.0/16"			# 
  serviceSubnet: 10.96.0.0/12
# 新增如下内容：
---
apiVersion: kubeproxy.config.k8s.io/v1alpha1
kind: KubeProxyConfiguration
featureGates:
  SupportIPVSProxyMode: true
mode: ipvs

kubeadm init --config=kubeadm-config.yml --upload-certs | tee kubeadm-init.log

（2）初始化。

kubeadm init --config=kubeadm-config.yml  | tee kubeadm-init.log

方便初始化日志查看，将其留存在 kubeadm-init.log 文件。

如果说某次执行 kubeadm init 初始化失败，在下一次执行 kubeadm init 初始化语句之前，先执行 kubeadm reset 命令。这个命令的作用是重置节点，可以把这个命令理解为：上一次 kubeadm init 初始化操作失败了，该命令清理了之前的失败环境。

执行过程：

[root@k8s-master xcbeyond]# kubeadm init --config=kubeadm-config.yml  | tee kubeadm-init.log
[init] Using Kubernetes version: v1.20.0
[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-master kubernetes kubernetes.default kubernetes.default.svc kubernetes.default.svc.cluster.local] and IPs [10.96.0.1 192.168.11.100]
[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 [192.168.11.100 127.0.0.1 ::1]
[certs] Generating "etcd/peer" certificate and key
[certs] etcd/peer serving cert is signed for DNS names [k8s-master localhost] and IPs [192.168.11.100 127.0.0.1 ::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 28.009413 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 k8s-master 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-master 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 192.168.11.100:6443 --token abcdef.0123456789abcdef \
    --discovery-token-ca-cert-hash sha256:79f34a5872b3df5817d29330ec055d14509a66c96c5de01bfa0d640fab671d90

4.2.3 加入主节点

在 Master 节点上 kubeadm init 执行成功后，注意日志末尾的提示，按要求在 Master、Node 节点上执行相关命令即可。

kubeadm init 初始化执行日志如下：

……
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 192.168.11.100:6443 --token abcdef.0123456789abcdef \
    --discovery-token-ca-cert-hash sha256:79f34a5872b3df5817d29330ec055d14509a66c96c5de01bfa0d640fab671d90

要使得非 root 用户可以运行 kubectl，请运行以下命令（是 kubeadm init 输出日志的部分内容）：

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

或者，如果你是 root 用户，则可以运行：

export KUBECONFIG=/etc/kubernetes/admin.conf

4.2.4 加入工作节点

工作节点是你的工作负载（容器和 Pod 等）运行的地方。要将新节点添加到集群，请对每台工作节点执行以下操作。

root 用户执行 kubeadm init 输出的命令：

kubeadm join 192.168.11.100:6443 --token abcdef.0123456789abcdef \
    --discovery-token-ca-cert-hash sha256:79f34a5872b3df5817d29330ec055d14509a66c96c5de01bfa0d640fab671d90

执行过程：

[root@k8s-node01 xcbeyond]# kubeadm join 192.168.11.100:6443 --token abcdef.0123456789abcdef \
>     --discovery-token-ca-cert-hash sha256:79f34a5872b3df5817d29330ec055d14509a66c96c5de01bfa0d640fab671d90
[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.

4.2.5 安装Pod网络附加插件

至此，在 Master 节点执行 kubectl get nodes 命令：

[root@k8s-master xcbeyond]# kubectl get nodes
NAME         STATUS     ROLES                  AGE   VERSION
k8s-master   NotReady   control-plane,master   1m8s   v1.20.2
k8s-node01   NotReady   <none>                 18s   v1.20.2

发现是 NotReady 状态，因为 Kubernetes 要求必须要存在一个网络，即：目前还没有构建 Pod 网络附加插件，此时需要安装 Pod 网络附加插件。

可直接使用官方提供的 kube-flannel.yml 文件，进行创建。

（1）下载官方提供的 kube-flannel.yml 文件。

文件地址：https://github.com/coreos/flannel/blob/master/Documentation/kube-flannel.yml

（2）创建网络。

[root@k8s-master xcbeyond]# kubectl create -f 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

（3）查看 Pod。

如果 flannel 还未 Running 状态，可稍等一会儿，等待构建成功。

[root@k8s-master xcbeyond]# kubectl get pod -n kube-system
NAME                                 READY   STATUS              RESTARTS   AGE
coredns-74ff55c5b-fr4jj              0/1     ContainerCreating   0          6m3s
coredns-74ff55c5b-wcj2h              0/1     ContainerCreating   0          6m3s
etcd-k8s-master                      1/1     Running             0          6m5s
kube-apiserver-k8s-master            1/1     Running             0          6m5s
kube-controller-manager-k8s-master   1/1     Running             0          6m5s
kube-flannel-ds-2nkcv                1/1     Running             0          13s
kube-flannel-ds-m8tf2                1/1     Running             0          13s
kube-proxy-mft9t                     0/1     CrashLoopBackOff    6          6m3s
kube-proxy-n67px                     0/1     CrashLoopBackOff    3          68s
kube-scheduler-k8s-master            1/1     Running             0          6m5s

（4）查看节点状态。

此时已经 Ready 状态。

[root@k8s-master xcbeyond]# kubectl get nodes
NAME         STATUS     ROLES                  AGE   VERSION
k8s-master   Ready    control-plane,master   6m30s   v1.20.2
k8s-node01   Ready    <none>                 85s     v1.20.2

4.3 集群环境验证

至此，基于 kubeadm 方式的集群搭建已完成，让我们一起在 Kubernetes 集群环境下开启 Kubernetes 的探索吧！

5、总结

安装过程中，可能会遇到各种形形色色的问题与障碍，大可不必担心，初次安装肯定会是这样的。

面对问题，有以下几点看法或建议：

  1. 遇到问题，说明你亲自动手过，这本身就是一种乐趣。（坑就是这么被踩出来的）
  2. 遇事不要慌，认真查看出错日志及提示。
  3. 根据关键错误信息，各种搜索齐上阵，尤其是在官方网站或 github。
  4. 解决问题后，要记录。

参考文章：

  1. https://kubernetes.io/zh/docs/setup/production-environment/tools/kubeadm/install-kubeadm/
  2. https://www.cnblogs.com/nb-blog/p/10636733.html
  3. https://www.cnblogs.com/shoufu/p/13047723.html