Kubeadm安装k8s集群
环境准备准备3台机安装一个master，两个Node的k8s集群，本文是在centos7的环境下安装k8s
192.168.144.2(k8s-master)
192.168.144.3(k8s-node-1)
192.168.144.4(k8s-node-2)
1,分别修改hostname
使用vim /etc/hostname修改各个节点为对应的名字
2，将对应的ip映射加入三台物理机的hosts
cat > /etc/hosts <<EOF
192.168.144.2k8s-master
192.168.144.3k8s-node-1
192.168.144.4k8s-node-2
EOF
3,关闭selinux防火墙
setenforce 0
4,安装docker-1.12.6并启动
yum install -y docker
systemctl start docker
systemctl enable docker
5，网络设置
cat > /etc/sysctl.d/k8s.conf <<EOF
net.bridge.bridge
-nf-call-ip6tables = 1
net.bridge.bridge
-nf-call-iptables = 1
EOF
并使它生效
sysctl -p /etc/sysctl.d/k8s.conf
安装k8s
1，增加k8s的yum源
使用测试是否可以访问k8s的网址
curl http://yum.kubernetes.io/repos/kubernetes-el7-x86_64
如果可以，使用下面命令增加一个yum源
curl http://yum.kubernetes.io/repos/kubernetes-el7-x86_64cat <<EOF > /etc/yum.repos.d/kubernetes.repo
name=Kubernetes
baseurl=http://yum.kubernetes.io/repos/kubernetes-el7-x86_64
enabled=1
gpgcheck=1
repo_gpgcheck=1
gpgkey=https://packages.cloud.google.com/yum/doc/yum-key.gpg
https://packages.cloud.google.com/yum/doc/rpm-package-key.gpg
EOF
2,安装kubeadm, kubelet, kubectl, kubernets-cni
yum install -y kubelet-1.6.2 kubeadm-1.6.2 kubectl-1.6.2 kubernetes-cni
systemctl enable kubelet.service
3,初始化集群（如果不能访问DOCKER镜像服务器，请提前准备好镜像）
kubeadm init --kubernetes-version=v1.6.2 --pod-network-cidr=10.96.0.0/16
WARNING: kubeadm is
in beta, please do not use it for production clusters.
Using Kubernetes version: v1.
6.2
Using Authorization mode: RBAC
Running pre
-flight checks
Starting the kubelet service
Generated CA certificate and key.
Generated API server certificate and key.
API Server serving cert is signed
for DNS names and IPs
Generated API server kubelet client certificate and key.
Generated service account token signing key and public key.
Generated front
-proxy CA certificate and key.
Generated front
-proxy client certificate and key.
Valid certificates and keys now exist
in "/etc/kubernetes/pki"
Wrote KubeConfig
file to disk: "/etc/kubernetes/admin.conf"
Wrote KubeConfig
file to disk: "/etc/kubernetes/kubelet.conf"
Wrote KubeConfig
file to disk: "/etc/kubernetes/controller-manager.conf"
Wrote KubeConfig
file to disk: "/etc/kubernetes/scheduler.conf"
Created API client, waiting
for the control plane to become ready
All control plane components are healthy after
14.583864 seconds
Waiting
for at least one node to register
First node has registered after
6.008990 seconds
Using token: e7986d.e440de5882342711
Created RBAC rules
Created essential addon: kube
-proxy
Created essential addon: kube
-dns
Your Kubernetes master has initialized successfully
!
To start using your cluster, you need to run (as a regular user):
sudo cp /etc/kubernetes/admin.conf $HOME/ sudo chown $(id -u):$(id -g) $HOME/admin.conf
export KUBECONFIG=$HOME/admin.conf
You should now deploy a pod network to the cluster.
Run "kubectl apply -f .yaml" with one of the options listed at:
http://kubernetes.io/docs/admin/addons/
You can now join any number of machines by running the following on each node
as root:
kubeadm join --token e7986d.e440de5882342711 192.168.144.2:6443
因为后续k8s的集群网络采用flannel安装，而flannel的默认网络是10.224.0.0/16，如果是后续不想修改kube-flannel.yml的网段为10.96.0.0/16，此处可以生命--service-cidr=10.244.0.0、16来指定
如果没有安装好，可以清理掉已安装的k8s，重新安装
kubeadm reset
ifconfig cni0 down
ip link delete cni0
ifconfig flannel.1 down
ip link delete flannel.
1
rm -rf /var/lib/cni/
4，为kubectl增加执行权限，可以调用api-server
sudo cp /etc/kubernetes/admin.conf $HOME/
sudo chown $(id -u):$(id -g) $HOME/admin.conf
export KUBECONFIG=$HOME/admin.conf
5，在master节点查看已有节点，当dns没有初始化完，状态不会变为Ready
kubectl get nodes
NAME STATUS AGE VERSION
node0 NotReady 3m v1.
6.1
6，查看POD状态
执行kubectl get pod --all-namespaces -o wide耐心等待，最后除了dns其他的pod都是running状态，当dns等待网络安装flannel后会自动变为running
7，使master node参与工作负载
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。
这里搭建的是测试环境可以使用下面的命令使Master Node参与工作负载
kubectl taint nodes --allnode-role.kubernetes.io/master-
8，安装Flannel初始化POD网络
mkdir -p flannel
cd flanne
wget https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel-rbac.yml
wget https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml
cp kube-flannel.yml kube-flannel.yml.default
sed -i 's/10.244.0.0/10.96.0.0/g' kube-flannel.yml
sed -i 's/"--kube-subnet-mgr"/"--kube-subnet-mgr", "--iface=eth0"/g' kube-flannel.yml
kubectl create -f kube-flannel-rbac.yml
kubectl apply -f kube-flannel.yml
此处有两个修改：
1，设置flannel的网段为10.96.0.0/16
2，指定网卡，不指定默认使用会换网卡lo
当所有的POD的状态都变成running后测试dns是否正常
kubectl run curl --image=radial/busyboxplus:curl -i --tty
接着会先是如下内容
Waiting for pod default/curl-2421989462-vldmp to be running, status is Pending, pod ready: false
Waiting
for pod default/curl-2421989462-vldmp to be running, status is Pending, pod ready: false
If you don
't see a command prompt, try pressing enter.
[ root@curl-2421989462-vldmp:/ ]$
然后在命令行输入nslookup kubernetes.default
[ root@curl-2421989462-vldmp:/ ]$ nslookup kubernetes.default
Server:
10.96.0.10
Address
1: 10.96.0.10 kube-dns.kube-system.svc.cluster.local
Name: kubernetes.default
Address
1: 10.96.0.1 kubernetes.default.svc.cluster.local
测试成功后删除测试的POD
kubectl delete deploy curl
9，将k8s-node-1和k8s-node-2添加到集群
执行上面初始化时，控制台打印的命令命令kubeadm join --token e7986d.e440de5882342711 192.168.144.2:6443
kubeadm join --token e7986d.e440de5882342711 192.168.144.2:6443
WARNING: kubeadm is
in beta, please do not use it for production clusters.
Running pre
-flight checks
Trying to connect to API Server
"192.168.144.2:6443"
Created cluster
-info discovery client, requesting info from "https://192.168.144.2:6443"
Cluster
info signature and contents are valid, will use API Server "https://192.168.144.2:6443"
Successfully established connection with API Server
"192.168.61.41:6443"
Detected server version: v1.
6.2
The server supports the Certificates API (certificates.k8s.io
/v1beta1)
Created API client to obtain unique certificate
for this node, generating keys and certificate signing request
Received signed certificate from the API server, generating KubeConfig...
Wrote KubeConfig
file to disk: "/etc/kubernetes/kubelet.conf"
Node
join complete:
* Certificate signing request sent to master and response
received.
* Kubelet informed of new secure connection details.
Run
'kubectl get nodes' on the master to see this machine join.
查看集群中节点
kubectl get nodes
NAME STATUS AGE VERSION
k8s
-master Ready 12m v1.6.2
k8s
-node-1 Ready 4m v1.6.2
k8s
-node-2 Ready 2m v1.6.2
10, Dashboard安装
mkdir -p dashboard
cd dashboard
wget https://git.io/kube-dashboard
mv kube-dashboard kube-dashboard.yml
kubectl create -f kube-dashboard.yml
kubectl proxy &
cd ..
执行kubectl get nodes --all-namespaces | grep dashboard查看节点是否启动成功
执行curl http://127.0.0.1:8001/ui查看能否访问得到页面
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