K8S学习-集群搭建

经过虚拟机配置,基础环境配置完毕后,就可以进入集群搭建的环节了

安装docker

[root@master ~]# yum install wget
# 切换镜像源
[root@master ~]# wget https://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo -O /etc/yum.repos.d/docker-ce.repo
# 查看当前镜像源中支持的docker版本
[root@master ~]# yum list docker-ce --showduplicates
# 安装特定版本的docker-ce
# 必须制定--setopt=obsoletes=0，否则yum会自动安装更高版本
[root@master ~]# yum install --setopt=obsoletes=0 docker-ce-18.06.3.ce-3.el7 -y
# 添加一个配置文件
# Docker 在默认情况下使用Vgroup Driver为cgroupfs，而Kubernetes推荐使用systemd来替代cgroupfs,并切换到阿里仓库源
[root@master ~]# mkdir /etc/docker
[root@master ~]# cat <<EOF> /etc/docker/daemon.json
{
	"exec-opts": ["native.cgroupdriver=systemd"],
	"registry-mirrors": ["https://kn0t2bca.mirror.aliyuncs.com"]
}
EOF
# 启动dokcer
[root@master ~]# systemctl restart docker
# 查看下docker是否启动成功
[root@master ~]# docker version
Client:
 Version:           18.06.3-ce
 API version:       1.38
 Go version:        go1.10.3
 Git commit:        d7080c1
 Built:             Wed Feb 20 02:26:51 2019
 OS/Arch:           linux/amd64
 Experimental:      false

Server:
 Engine:
  Version:          18.06.3-ce
  API version:      1.38 (minimum version 1.12)
  Go version:       go1.10.3
  Git commit:       d7080c1
  Built:            Wed Feb 20 02:28:17 2019
  OS/Arch:          linux/amd64
  Experimental:     false
# 设置开机自启
[root@master ~]# systemctl enable docker

安装Kubernetes组件

# 由于kubernetes的镜像在国外，速度比较慢，这里切换成国内的镜像源
# 编辑/etc/yum.repos.d/kubernetes.repo,添加下面的配置
[kubernetes]
name=Kubernetes
baseurl=http://mirrors.aliyun.com/kubernetes/yum/repos/kubernetes-el7-x86_64
enabled=1
gpgchech=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

# 安装kubeadm、kubelet和kubectl
[root@master ~]# yum install --setopt=obsoletes=0 kubeadm-1.17.4-0 kubelet-1.17.4-0 kubectl-1.17.4-0 -y

# 配置kubelet的cgroup
#编辑/etc/sysconfig/kubelet, 添加下面的配置
KUBELET_CGROUP_ARGS="--cgroup-driver=systemd"
KUBE_PROXY_MODE="ipvs"

# 设置kubelet开机自启
[root@master ~]# systemctl enable kubelet

准备集群镜像

# 在安装kubernetes集群之前，必须要提前准备好集群需要的镜像，所需镜像可以通过下面命令查看
[root@master ~]# kubeadm config images list

# 下载镜像
# 此镜像kubernetes的仓库中，由于网络原因，无法连接，下面提供了一种替换方案
# 步骤1
images=(
	kube-apiserver:v1.17.17
	kube-controller-manager:v1.17.17
	kube-scheduler:v1.17.17
	kube-proxy:v1.17.17
	pause:3.1
	etcd:3.4.3-0
	coredns:1.6.5
)
# 步骤2
for imageName in ${images[@]};do
	docker pull registry.cn-hangzhou.aliyuncs.com/google_containers/$imageName
	docker tag registry.cn-hangzhou.aliyuncs.com/google_containers/$imageName k8s.gcr.io/$imageName
	docker rmi registry.cn-hangzhou.aliyuncs.com/google_containers/$imageName 
done
# 验证是否安装好
[root@master ~]# docker images
REPOSITORY                           TAG                 IMAGE ID            CREATED             SIZE
k8s.gcr.io/kube-proxy                v1.17.17            3ef67d180564        2 years ago         117MB
k8s.gcr.io/kube-controller-manager   v1.17.17            0ddd96ecb9e5        2 years ago         161MB
k8s.gcr.io/kube-scheduler            v1.17.17            d415ebbf09db        2 years ago         94.4MB
k8s.gcr.io/kube-apiserver            v1.17.17            38db32e0f351        2 years ago         171MB
k8s.gcr.io/coredns                   1.6.5               70f311871ae1        3 years ago         41.6MB
k8s.gcr.io/etcd                      3.4.3-0             303ce5db0e90        3 years ago         288MB
k8s.gcr.io/pause                     3.1                 da86e6ba6ca1        5 years ago         742kB

集群初始化

注意: 下面的操作只需要在master节点上执行即可

# 创建集群,注意apiserver-advertise-address为当前机器ip
[root@master ~]# kubeadm init \
	--apiserver-advertise-address=192.168.145.100 \
	--image-repository registry.aliyuncs.com/google_containers \
	--kubernetes-version=v1.17.17 \
	--service-cidr=10.96.0.0/12 \
	--pod-network-cidr=10.244.0.0/16
# 按照提示创建必要文件
[root@master ~]# mkdir -p $HOME/.kube
[root@master ~]# sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
[root@master ~]# sudo chown $(id -u):$(id -g) $HOME/.kube/config

上边的命令执行完毕后,会看到如下输出,注意记录关键信息

# 注意记录关键信息
Your Kubernetes control-plane has initialized successfully! # 安装成功

To start using your cluster, you need to run the following as a regular user:
  # 还需要做的事情
  mkdir -p $HOME/.kube
  sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
  sudo chown $(id -u):$(id -g) $HOME/.kube/config

# 集群安装完毕,但是网络是没有的,还需要执行下边的命令
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/
# 如果想在集群里加入node节点,需要在node节点以root身份执行下方的命令
Then you can join any number of worker nodes by running the following on each as root:

kubeadm join 192.168.145.100:6443 --token ez0nsy.mwcwhlp84ubowcr1 \
    --discovery-token-ca-cert-hash sha256:054584d999625b5a39f7ccf02aefa173f21926603f6ccd219fb37fa0245ea580

注意: 下面的操作只需要在node节点上执行即可,需要将上方输出的命令复制过来执行

[root@node2 ~]# kubeadm join 192.168.145.100:6443 --token ez0nsy.mwcwhlp84ubowcr1 \
>     --discovery-token-ca-cert-hash sha256:054584d999625b5a39f7ccf02aefa173f21926603f6ccd219fb37fa0245ea580

查看所有节点,验证是否成功

[root@master ~]# kubectl get nodes
NAME     STATUS     ROLES    AGE   VERSION
master   NotReady   master   10m   v1.17.4
node1    NotReady   <none>   69s   v1.17.4
node2    NotReady   <none>   4s    v1.17.4

安装网络插件

kubernetes支持多种网络插件,比如flannel,calico,canal等,任选一种即可,本次选择flannel

注意: 只在master节点操作即可

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

过个一两分钟,查看节点状态

[root@master ~]# kubectl get nodes
NAME     STATUS   ROLES    AGE   VERSION
master   Ready    master   21m   v1.17.4
node1    Ready    <none>   12m   v1.17.4
node2    Ready    <none>   11m   v1.17.4

全是ready即可

服务部署(验证集群是否可用)

注意:只通过master节点操作

# 部署nginx
[root@master ~]# kubectl create deployment nginx --image=nginx:1.14-alpine
# 暴露端口
[root@master ~]# kubectl expose deployment nginx --port=80 --type=NodePort
# 查看服务状态
[root@master ~]# kubectl get pod
NAME                     READY   STATUS    RESTARTS   AGE
nginx-6867cdf567-pmj4d   1/1     Running   0          2m13s
[root@master ~]# kubectl get service
NAME         TYPE        CLUSTER-IP     EXTERNAL-IP   PORT(S)        AGE
kubernetes   ClusterIP   10.96.0.1      <none>        443/TCP        27m
nginx        NodePort    10.97.243.70   <none>        80:30322/TCP   83s

# 注意关注输出的PORT(S),nginx的80端口对应的是30322端口,也就是对外暴露的30322端口

浏览器访问验证http://192.168.145.100:30322/ 到这儿集群搭建成功~