一、环境介绍

centos7系统机器三台：
192.168.3.100: 用来安装kubernetes master
192.168.3.101: 用作kubernetes node1
192.168.3.102: 用作kubernetes node2

二、准备工作

以下步骤在三台主机上都要操作。
需要pull docker镜像，请先安装docker。

1、K8s和docker版本关系

https://github.com/kubernetes/kubernetes

2、安装docker

从CentOS OS存储库中使用docker，则docker版本可能较旧，无法与Kubernetes v1.13.0及更高版本一起使用。
这里我们安装18.06.3版本

yum install -y -q yum-utils device-mapper-persistent-data lvm2 > /dev/null 2>&1
yum-config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo > /dev/null 2>&1
yum install -y -q docker-ce-18.06.3.ce >/dev/null 2>&1

启动docker

systemctl enable docker && systemctl start docker
docker version

3、关闭系统运行的防火墙

如果系统开启了防火墙则按如下步骤关闭防火墙

[root@localhost]# systemctl stop firewalld
[root@localhost]# systemctl disable firewalld

4、关闭selinux

[root@localhost]# setenforce 0
[root@localhost]# sed -i '/^SELINUX=/cSELINUX=disabled' /etc/sysconfig/selinux

或者编辑/etc/selinux/config

[root@localhost]# vi /etc/selinux/config

将SELINUX=enforcing改为SELINUX=disabled，重启后生效
查看状态

[root@localhost]# sestatus
SELinux status: disabled

5、关闭swap

kubeadm不支持swap
执行

[root@localhost yum.repos.d]# swapoff -a

或者编辑/etc/fstab注释掉swap

[root@localhost yum.repos.d]# cat /etc/fstab
#
# /etc/fstab
# Created by anaconda on Fri Oct 18 00:03:01 2019
#
# Accessible filesystems, by reference, are maintained under '/dev/disk'
# See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info
#
UUID=1a73fb9d-095b-4302-aa87-4a49783c0133 /                       xfs     defaults        0 0
UUID=e293a721-617e-4cdd-8cb9-d2e895427b03 /boot                   xfs     defaults        0 0
#UUID=73e88a54-4574-4f0a-8a4f-d57d2bc2ee46 swap                    swap    defaults        0 0

6、修改主机名

三台主机分别设置master、node1、node2

[root@localhost kubernetes]# cat >> /etc/sysconfig/network << EOF
hostname=master
EOF
[root@localhost kubernetes]# cat /etc/sysconfig/network
# Created by anaconda
hostname=master

或者

[root@localhost]#hostnamectl set-hostname master
[root@localhost]#hostnamectl set-hostname node1
[root@localhost]#hostnamectl set-hostname node2

7、配置/etc/hosts

每台主机上都执行

[root@localhost]#echo "192.168.3.100 master" >> /etc/hosts
[root@localhost]#echo "192.168.3.101 node1" >> /etc/hosts
[root@localhost]#echo "192.168.3.102 node2" >> /etc/hosts

8、配置内核参数

将桥接的IPv4流量传递到iptables的链

[root@localhost]#cat <<EOF >  /etc/sysctl.d/k8s.conf
net.bridge.bridge-nf-call-ip6tables = 1
net.bridge.bridge-nf-call-iptables = 1
----net.bridge.bridge-nf-call-arptables = 1
net.ipv4.ip_forward = 1
EOF

使如上配置生效

[root@localhost]#sysctl --system

9、配置CentOS YUM源

//配置国内tencent yum源地址、epel源地址、Kubernetes源地址
[root@localhost]#mkdir -p /etc/yum.repos.d/repos.bak
[root@localhost]#mv /etc/yum.repos.d/*.repo /etc/yum.repos.d/repos.bak
[root@localhost]#wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.cloud.tencent.com/repo/centos7_base.repo
[root@localhost]#wget -O /etc/yum.repos.d/epel.repo http://mirrors.cloud.tencent.com/repo/epel-7.repo
[root@localhost]#yum clean all && yum makecache

//配置国内Kubernetes源地址
[root@localhost]#cat <<EOF > /etc/yum.repos.d/kubernetes.repo 
[kubernetes]
name=Kubernetes 
baseurl=https://mirrors.aliyun.com/kubernetes/yum/repos/kubernetes-el7-x86_64
enabled=1
gpgcheck=1
repo_gpgcheck=1
gpgkey=https://mirrors.aliyun.com/kubernetes/yum/doc/yum-key.gpg https://mirrors.aliyun.com/kubernetes/yum/doc/rpm-package-key.gpg
EOF

10、安装工具

指定版本号

[root@localhost]#yum install -y kubelet-1.16.0 kubeadm-1.16.0 kubectl-1.16.0 --disableexcludes=kubernetes

不指定版本号

install -y kubelet kubeadm kubectl --disableexcludes=kubernetes

说明：–disableexcludes=kubernetes #禁用除kubernetes之外的仓库，可以不带这个参数
启动工具

[root@localhost]#systemctl enable kubelet
[root@localhost]#systemctl start kubelet

其他命令

systemctl status kubelet
systemctl stop kubelet
systemctl restart kubelet

11、初始化获取要下载的镜像列表

[root@master ~]# cd /home
[root@master home]# ls
apache-zookeeper-3.5.6-bin  jdk1.8.0_231  kafka_2.12-2.3.1
[root@master home]# kubeadm config images list
W1115 18:05:31.432259   17146 version.go:101] could not fetch a Kubernetes version from the internet: unable to get URL "https://dl.k8s.io/release/stable-1.txt": Get https://dl.k8s.io/release/stable-1.txt: net/http: request canceled while waiting for connection (Client.Timeout exceeded while awaiting headers)
W1115 18:05:31.436956   17146 version.go:102] falling back to the local client version: v1.16.3
k8s.gcr.io/kube-apiserver:v1.16.3
k8s.gcr.io/kube-controller-manager:v1.16.3
k8s.gcr.io/kube-scheduler:v1.16.3
k8s.gcr.io/kube-proxy:v1.16.3
k8s.gcr.io/pause:3.1
k8s.gcr.io/etcd:3.3.15-0
k8s.gcr.io/coredns:1.6.2

12、生成默认kubeadm.conf文件

执行下面命令，会在当前目录生成kubeadm.conf文件

[root@master home]#kubeadm config print init-defaults > kubeadm.conf

13、修改kubeadm.conf镜像源

kubeadm.conf这个配置文件默认会从google的镜像仓库地址k8s.gcr.io下载镜像，国内下载不了。因此，我们通过下面的方法把地址改成国内的，比如用阿里的。
编辑kubeadm.conf文件，把imageRepository的value改成下面的
imageRepository: registry.aliyuncs.com/google_containers
kubeadm.conf文件里的kubeadm和k8s版本必须匹配，不能一高一低，如果不匹配，修改kubeadm.conf下面k8s的版本号即可

[root@master home]#vi kubeadm.conf

14、下载需要用到的镜像

在kubeadm.conf所在目录执行

[[root@master home]#kubeadm config images pull --config kubeadm.conf

注意：上面显示的1.16.3，但这里pull到的是1.16.0，没关系

[root@master home]# docker images

15、docker镜像重新打tag

镜像下载好后，还需要tag下载好的镜像，让下载好的镜像都是带有 k8s.gcr.io 标识的，如果不打tag变成k8s.gcr.io，那么后面用kubeadm安装会出现问题，因为kubeadm里面只认 google自身的模式。打tag后删除带有 registry.aliyuncs.com 标识的镜像。

重新打tag

docker tag registry.aliyuncs.com/google_containers/coredns:1.6.2 k8s.gcr.io/coredns:1.6.2
docker tag registry.aliyuncs.com/google_containers/kube-proxy:v1.16.0 k8s.gcr.io/kube-proxy:v1.16.0
docker tag registry.aliyuncs.com/google_containers/kube-apiserver:v1.16.0 k8s.gcr.io/kube-apiserver:v1.16.0
docker tag registry.aliyuncs.com/google_containers/kube-controller-manager:v1.16.0 k8s.gcr.io/kube-controller-manager:v1.16.0
docker tag registry.aliyuncs.com/google_containers/kube-scheduler:v1.16.0 k8s.gcr.io/kube-scheduler:v1.16.0
docker tag registry.aliyuncs.com/google_containers/etcd:3.3.15-0 k8s.gcr.io/etcd:3.3.15-0
docker tag registry.aliyuncs.com/google_containers/pause:3.1 k8s.gcr.io/pause:3.1

删除带有 registry.aliyuncs.com 标识的镜像

docker rmi registry.aliyuncs.com/google_containers/coredns:1.6.2
docker rmi registry.aliyuncs.com/google_containers/kube-proxy:v1.16.0
docker rmi registry.aliyuncs.com/google_containers/kube-apiserver:v1.16.0
docker rmi registry.aliyuncs.com/google_containers/kube-controller-manager:v1.16.0
docker rmi registry.aliyuncs.com/google_containers/kube-scheduler:v1.16.0
docker rmi registry.aliyuncs.com/google_containers/etcd:3.3.15-0
docker rmi registry.aliyuncs.com/google_containers/pause:3.1

三、部署master节点

1、Kubernetes集群初始化

执行

[root@master ~]# kubeadm init --kubernetes-version=v1.16.0 --pod-network-cidr= 10.244.0.0/16 --apiserver-advertise-address=192.168.3.100

执行成功结果

[init] Using Kubernetes version: v1.16.0
[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'
[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] Activating the kubelet service
[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 [master kubernetes kubernetes.default kubernetes.default.svc kubernetes.default.svc.cluster.local] and IPs [10.96.0.1 192.168.3.100]
[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 [master localhost] and IPs [192.168.3.100 127.0.0.1 ::1]
[certs] Generating "etcd/peer" certificate and key
[certs] etcd/peer serving cert is signed for DNS names [master localhost] and IPs [192.168.3.100 127.0.0.1 ::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
[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
[kubelet-check] Initial timeout of 40s passed.
[apiclient] All control plane components are healthy after 209.010947 seconds
[upload-config] Storing the configuration used in ConfigMap "kubeadm-config" in the "kube-system" Namespace
[kubelet] Creating a ConfigMap "kubelet-config-1.16" 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 master as control-plane by adding the label "node-role.kubernetes.io/master=''"
[mark-control-plane] Marking the node master as control-plane by adding the taints [node-role.kubernetes.io/master:NoSchedule]
[bootstrap-token] Using token: vmuuvn.q7q14t5135zm9xk0
[bootstrap-token] Configuring bootstrap tokens, cluster-info ConfigMap, RBAC Roles
[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
[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 192.168.3.100:6443 --token vmuuvn.q7q14t5135zm9xk0 \
    --discovery-token-ca-cert-hash sha256:c302e2c93d2fe86be7f817534828224469a19c5ccbbf9b246f3695127c3ea611

记录最后的输出，node节点加入需要用到
kubeadm join 192.168.3.100:6443 --token vmuuvn.q7q14t5135zm9xk0
–discovery-token-ca-cert-hash sha256:c302e2c93d2fe86be7f817534828224469a19c5ccbbf9b246f3695127c3ea611

如果init失败，重启kubeadm再执行init

[root@master ~]# kubeadm reset

初始化成功后会在/etc/kubernetes/成下面的文件，如果没有需要重新init

[root@master home]# ll /etc/kubernetes/
total 36
-rw-------  1 root root 5453 Nov 15 17:42 admin.conf
-rw-------  1 root root 5485 Nov 15 17:42 controller-manager.conf
-rw-------  1 root root 5457 Nov 15 17:42 kubelet.conf
drwxr-xr-x. 2 root root  113 Nov 15 17:42 manifests
drwxr-xr-x  3 root root 4096 Nov 15 17:42 pki
-rw-------  1 root root 5437 Nov 15 17:42 scheduler.conf

注意：kubeadm reset是清理环境，执行后，master要重新init。如果node已经加入集群，那么node也要reset重启kubelet并要重新join

[root@node1 home]#kubeadm reset
[root@node1 home]#systemctl daemon-reload && systemctl restart kubelet
[root@node1 home]# kubeadm join 192.168.3.100:6443 --token vmuuvn.q7q14t5135zm9xk0 \
    --discovery-token-ca-cert-hash sha256:c302e2c93d2fe86be7f817534828224469a19c5ccbbf9b246f3695127c3ea611

2、配置权限

当前用户，执行以下步骤(系统由admin.conf文件启动kubernetes,如果不配置会起不来)

root@master home]# mkdir -p $HOME/.kube
[root@master home]# cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
[root@master home]# chown $(id -u):$(id -g) $HOME/.kube/config

3、部署flannel网络（安装pod网络附加组件）

k8s 支持很多种网络方案，在这里使用的是经典的 flannel 方案，还有Calico方式。

查看flannel版本
https://github.com/coreos/flannel

执行命令开始安装。注：下面这个地址是v0.11.0-amd6版本的

[root@master home]#kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/62e44c867a2846fefb68bd5f178daf4da3095ccb/Documentation/kube-flannel.yml

安装结果

clusterrole.rbac.authorization.k8s.io/flannel created
clusterrolebinding.rbac.authorization.k8s.io/flannel created
serviceaccount/flannel created
configmap/kube-flannel-cfg created
unable to recognize "https://raw.githubusercontent.com/coreos/flannel/62e44c867a2846fefb68bd5f178daf4da3095ccb/Documentation/kube-flannel.yml": no matches for kind "PodSecurityPolicy" in version "extensions/v1beta1"
unable to recognize "https://raw.githubusercontent.com/coreos/flannel/62e44c867a2846fefb68bd5f178daf4da3095ccb/Documentation/kube-flannel.yml": no matches for kind "DaemonSet" in version "extensions/v1beta1"
unable to recognize "https://raw.githubusercontent.com/coreos/flannel/62e44c867a2846fefb68bd5f178daf4da3095ccb/Documentation/kube-flannel.yml": no matches for kind "DaemonSet" in version "extensions/v1beta1"
unable to recognize "https://raw.githubusercontent.com/coreos/flannel/62e44c867a2846fefb68bd5f178daf4da3095ccb/Documentation/kube-flannel.yml": no matches for kind "DaemonSet" in version "extensions/v1beta1"
unable to recognize "https://raw.githubusercontent.com/coreos/flannel/62e44c867a2846fefb68bd5f178daf4da3095ccb/Documentation/kube-flannel.yml": no matches for kind "DaemonSet" in version "extensions/v1beta1"
unable to recognize "https://raw.githubusercontent.com/coreos/flannel/62e44c867a2846fefb68bd5f178daf4da3095ccb/Documentation/kube-flannel.yml": no matches for kind "DaemonSet" in version "extensions/v1beta1"

如果一直pull不下来，默认的flannel配置文件拉取镜像在国外，国内拉取失败，很多网上文章没注意这一步，导致flannel部署失败，如下解决

[root@master home]# mkdir flannel
[root@master home]# wget -P flannel/ https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml
[root@master home]#sed -i 's#quay.io#quay-mirror.qiniu.com#g' flannel/kube-flannel.yml
[root@master home]#kubectl apply -f flannel/kube-flannel.yml

执行获取pods列表命令，查看相关状态

[root@master home]# kubectl get pods --all-namespaces
NAMESPACE     NAME                             READY   STATUS    RESTARTS   AGE
kube-system   coredns-5644d7b6d9-2pxtt         0/1     Pending   0          44m
kube-system   coredns-5644d7b6d9-kcwxm         0/1     Pending   0          44m
kube-system   etcd-master                      1/1     Running   0          44m
kube-system   kube-apiserver-master            1/1     Running   1          43m
kube-system   kube-controller-manager-master   1/1     Running   8          44m
kube-system   kube-proxy-vwtgq                 1/1     Running   0          44m
kube-system   kube-scheduler-master            1/1     Running   7          44m

查看主节点情况

[root@master ~]# kubectl get nodes
NAME     STATUS   ROLES    AGE     VERSION
master   Ready    master   4h29m   v1.16.3

4、将Master作为工作节点（可选）

使用kubeadm初始化的集群，出于安全考虑Pod不会被调度到Master Node上，也就是说Master Node不参与工作负载，这样Master的资源就浪费了。在Master节点上，可以运行以下命令使其作为一个工作节点

[root@master ~]#kubectl taint nodes --all node-role.kubernetes.io/master-

禁止master部署pod

[root@master ~]#kubectl taint nodes k8s node-role.kubernetes.io/master=true:NoSchedule

关于污点，网上资料参考：
使用kubeadm搭建的集群默认就给 master 节点添加了一个污点标记，所以我们看到我们平时的 pod 都没有被调度到 master 上去。

[root@master ~]#kubectl describe node master （注：master node name）

有一条关于 Taints 的信息：node-role.kubernetes.io/master:NoSchedule，就表示给 master 节点打了一个污点的标记，其中影响的参数是NoSchedule，表示 pod 不会被调度到标记为 taints 的节点，除了 NoSchedule 外，还有另外两个选项：
PreferNoSchedule：NoSchedule 的软策略版本，表示尽量不调度到污点节点上去
NoExecute：该选项意味着一旦 Taint 生效，如该节点内正在运行的 pod 没有对应 Tolerate 设置，会直接被逐出

四、部署node节点

jion集群

[root@node1 ~]# kubeadm join 192.168.3.100:6443 --token vmuuvn.q7q14t5135zm9xk0 \
    --discovery-token-ca-cert-hash sha256:c302e2c93d2fe86be7f817534828224469a19c5ccbbf9b246f3695127c3ea611

如果在master初始化的时候没有记下jion命令，在master上使用kubeadm token create --print-join-command查询

五、卸载k8s

1、清理运行到k8s群集中的pod

$ kubectl delete node --all

2、删除数据卷和备份

$ for service in kube-apiserver kube-controller-manager kubectl kubelet kube-proxy kube-scheduler; do
      systemctl stop $service
  done
$ yum -y remove kubernetes #if it's registered as a service

3、卸载工具

yum remove -y kubelet kubectl

4、清理文件/文件夹

rm -rf ~/.kube/
rm -rf /etc/kubernetes/
rm -rf /etc/systemd/system/kubelet.service.d
rm -rf /etc/systemd/system/kubelet.service
rm -rf /usr/bin/kube*
rm -rf /etc/cni
rm -rf /opt/cni
rm -rf /var/lib/etcd
rm -rf /var/etcd
rm -rf /var/lib/cni/flannel/* && rm -rf /var/lib/cni/networks/cbr0/* && ip link delete cni0
rm -rf /var/lib/cni/networks/cni0/*

5、清理容器

docker rm -f $(docker ps -qa)
#删除所有的数据卷
docker volume rm $(docker volume ls -q)
#再次显示所有的容器和数据卷，确保没有残留
docker ps -a
docker volume ls

六、验证

[root@master ~]# kubectl get nodes -o wide

七、问题集锦

《kubeadm安装K8s 1.16集群–问题集锦》