通过kubeadmin安装三节点k8s
通过kubeadmin安装三节点k8s1.配置kubernetes的yum源2.查看已经启动的pod3.网络插件4.核心组件状态5.node加入三台机器2C4G192.168.56.71 node1192.168.56.72 node2192.168.56.73 node3参考https://kubernetes.io/docs/reference/setup-tools/kubeadm/impl
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通过kubeadmin安装三节点k8s
三台机器
2C4G
192.168.56.71 node1
192.168.56.72 node2
192.168.56.73 node3
参考
https://kubernetes.io/docs/reference/setup-tools/kubeadm/implementation-details/
1.配置kubernetes的yum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
执行下列命令刷新yum源缓存
# yum clean all
# yum makecache
# yum repolist
得到这面这个列表，说明源配置正确
[root@MiWiFi-R1CM-srv yum.repos.d]# yum repolist
已加载插件：fastestmirror
Loading mirror speeds from cached hostfile
源标识 源名称 状态
base/7/x86_64 CentOS-7 - Base - 163.com 10,019
docker-ce-stable/x86_64 Docker CE Stable - x86_64 28
extras/7/x86_64 CentOS-7 - Extras - 163.com 321
kubernetes Kubernetes 299
updates/7/x86_64 CentOS-7 - Updates - 163.com 628
repolist: 11,295
###4.安装kubeadm
yum install -y kubeadm
系统就会帮我们自动安装最新版的kubeadm了（我安装的时候是1.13.1），一共会安装kubelet、kubeadm、kubectl、kubernetes-cni这四个程序。
kubeadm：k8集群的一键部署工具，通过把k8的各类核心组件和插件以pod的方式部署来简化安装过程
kubelet：运行在每个节点上的node agent，k8集群通过kubelet真正的去操作每个节点上的容器，由于需要直接操作宿主机的各类资源，所以没有放在pod里面，还是通过服务的形式装在系统里面
kubectl：kubernetes的命令行工具，通过连接api-server完成对于k8的各类操作
kubernetes-cni：k8的虚拟网络设备，通过在宿主机上虚拟一个cni0网桥，来完成pod之间的网络通讯，作用和docker0类似。
安装完后，执行
[root@node1 ~]# kubeadm version
kubeadm version: &version.Info{Major:"1", Minor:"18", GitVersion:"v1.18.2", GitCommit:"52c56ce7a8272c798dbc29846288d7cd9fbae032", GitTreeState:"clean", BuildDate:"2020-04-16T11:54:15Z", GoVersion:"go1.13.9", Compiler:"gc", Platform:"linux/amd64"}
可以看到装的是1.18.2的版本
//pod使用的网段
10.16.0.0/16
kubeadm init --kubernetes-version=v1.18.2 --image-repository registry.aliyuncs.com/google_containers --pod-network-cidr=10.16.0.0/16 --apiserver-advertise-address=192.168.56.71
成功后可看到
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 192.168.56.71:6443 --token vji3ft.jlfs2w3fsqvcm5rt \
--discovery-token-ca-cert-hash sha256:640d7f9ccd1fa36eb9f92c091983cde5a5300b6233353f602f5b373bbad92d95
2.查看已经启动的pod
[root@node1 ~]# kubectl get pods -n kube-system
NAME READY STATUS RESTARTS AGE
coredns-7ff77c879f-769jq 0/1 Pending 0 21m
coredns-7ff77c879f-d72rh 0/1 Pending 0 21m
etcd-node1 1/1 Running 0 21m
kube-apiserver-node1 1/1 Running 0 21m
kube-controller-manager-node1 1/1 Running 0 21m
kube-proxy-frxlt 1/1 Running 0 14m
kube-proxy-kpf8f 1/1 Running 0 21m
kube-scheduler-node1 1/1 Running 0 21m
话不多说，依次执行
[root@node1 ~]# mkdir -p $HOME/.kube
[root@node1 ~]# sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
[root@node1 ~]# sudo chown $(id -u):$(id -g) $HOME/.kube/config
如果不加网络插件，将节点加入，然后查看节点状态如下
[root@node1 ~]# kubectl get node
NAME STATUS ROLES AGE VERSION
node1 NotReady master 11m v1.18.2
node2 NotReady <none> 4m45s v1.18.2
3.网络插件
网络插件我们使用calico
wget https://docs.projectcalico.org/v3.8/manifests/calico.yaml
sed -i -e "s?192.168.0.0/16?10.16.0.0/16?g" calico.yaml
kubectl apply -f calico.yaml
再次查看,可与看到coredns已经从pending=>Running
[root@node1 ~]# kubectl get pods -n kube-system
NAME READY STATUS RESTARTS AGE
calico-kube-controllers-77c5fc8d7f-bcdhs 1/1 Running 0 2m32s
calico-node-cmpl6 1/1 Running 0 2m33s
calico-node-x4sqc 1/1 Running 0 2m33s
coredns-7ff77c879f-769jq 1/1 Running 0 39m
coredns-7ff77c879f-d72rh 1/1 Running 0 39m
etcd-node1 1/1 Running 0 39m
kube-apiserver-node1 1/1 Running 0 39m
kube-controller-manager-node1 1/1 Running 0 39m
kube-proxy-frxlt 1/1 Running 0 33m
kube-proxy-kpf8f 1/1 Running 0 39m
kube-scheduler-node1 1/1 Running 0 39m
节点NotReady=>Ready
[root@node1 ~]# kubectl get nodes
NAME STATUS ROLES AGE VERSION
node1 Ready master 41m v1.18.2
node2 Ready <none> 34m v1.18.2
4.核心组件状态
[root@node1 ~]# kubectl get componentstatus
NAME STATUS MESSAGE ERROR
scheduler Healthy ok
controller-manager Healthy ok
etcd-0 Healthy {"health":"true"}
5.node加入
node上执行join之后，执行kubectl命令报错
[root@node3 ~]# kubectl get node
error: no configuration has been provided, try setting KUBERNETES_MASTER environment variable
解决方案
复制master上/etc/kubernetes/admin.conf到node
然后执行
-----------------------export KUBECONFIG=/etc/kubernetes/admin.conf
echo "export KUBECONFIG=/etc/kubernetes/admin.conf" >> ~/.bash_profile
永久可生效
source ~/.bash_profile
[root@node3 ~]# kubectl get node
NAME STATUS ROLES AGE VERSION
node1 Ready master 60m v1.18.2
node2 Ready <none> 54m v1.18.2
node3 Ready <none> 15m v1.18.2
问题解决
6.node重启后kubelet无法正常启动
三个节点都执行
[root@node2 ~]# systemctl enable kubelet
Created symlink from /etc/systemd/system/multi-user.target.wants/kubelet.service to /usr/lib/systemd/system/kubelet.service.
Master重启后无法正常启动,node "" not found** Unable to register node “node1” with API server:
May 12 16:12:29 node1 kubelet[6726]: I0512 16:12:29.851144 6726 kubelet_node_status.go:70] Attempting to register node node1
May 12 16:12:29 node1 kubelet[6726]: E0512 16:12:29.911997 6726 kubelet.go:2267] node "node1" not found
May 12 16:12:30 node1 kubelet[6726]: E0512 16:12:30.012553 6726 kubelet.go:2267] node "node1" not found
May 12 16:12:30 node1 kubelet[6726]: E0512 16:12:30.017299 6726 kubelet_node_status.go:92] Unable to register node "node1" with API server: Post https://192.168.56.71:6443/api/v1/nodes: dia...nection refused
May 12 16:12:30 node1 kubelet[6726]: E0512 16:12:30.112649 6726 kubelet.go:2267] node "node1" not found
原因
1.8版本之前.开启rbac后,apiserver默认绑定system:nodes组到system:node的clusterrole。v1.8之后,此绑定默认不存在,需要手工绑定,否则kubelet启动后会报认证错误，使用kubectl get nodes查看无法成为Ready状态
解决方案
使用命令kubectl get clusterrolebinding和kubectl get clusterrole可以查看系统中的角色与角色绑定
使用命令kubectl describe clusterrolebindings system:node查看system:node角色绑定的详细信息
创建角色绑定
在整个集群中授予 ClusterRole ，包括所有命名空间
kubectl create clusterrolebinding kubelet-node-clusterbinding --clusterrole=system:node --group=system:nodes
kubectl describe clusterrolebindings kubelet-node-clusterbinding
可以看到
[root@node1 ~]# kubectl describe clusterrolebindings kubelet-node-clusterbinding
Name: kubelet-node-clusterbinding
Labels: <none>
Annotations: <none>
Role:
Kind: ClusterRole
Name: system:node
Subjects:
Kind Name Namespace
---- ---- ---------
Group system:nodes
重启后生效，至此问题解决
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