快速部署一个Kubernetes集群

官方提供的三种部署方式

minikube

Minikube是一个工具，可以在本地快速运行一个单点的Kubernetes，仅用于尝试Kubernetes或日常开发的用户使用。

部署地址：https://kubernetes.io/docs/setup/minikube/

kubeadm

Kubeadm也是一个工具，提供kubeadm init和kubeadm join，用于快速部署Kubernetes集群。

部署地址：https://kubernetes.io/docs/reference/setup-tools/kubeadm/kubeadm/

二进制

推荐，从官方下载发行版的二进制包，手动部署每个组件，组成Kubernetes集群。

下载地址：https://github.com/kubernetes/kubernetes/releases

1. 安装要求

在开始之前，部署Kubernetes集群机器需要满足以下几个条件：

- 一台或多台机器，操作系统 CentOS7.x-86_x64
- 硬件配置：2GB或更多RAM，2个CPU或更多CPU，硬盘30GB或更多
- 集群中所有机器之间网络互通
- 可以访问外网，需要拉取镜像
- 禁止swap分区

2. 学习目标

1. 在所有节点上安装Docker和kubeadm
2. 部署Kubernetes Master
3. 部署容器网络插件
4. 部署 Kubernetes Node，将节点加入Kubernetes集群中
5. 部署Dashboard Web页面，可视化查看Kubernetes资源

3. 准备环境

关闭防火墙：

systemctl stop firewalld
systemctl disable firewalld

关闭selinux：

sed -i 's/enforcing/disabled/' /etc/selinux/config 
setenforce 0

关闭swap：

swapoff -a # 临时
vim /etc/fstab # 永久

添加主机名与IP对应关系）：

cat /etc/hosts
192.168.140.130 k8s-master
192.168.140.131 k8s-node1
192.168.140.132 k8s-node2

设置Maeter/node1/node2主机名：

hostnamectl set-hostname k8s-master
hostnamectl set-hostname k8s-node1
hostnamectl set-hostname k8s-node2

将桥接的IPv4流量传递到iptables的链：

cat > /etc/sysctl.d/k8s.conf << EOF
net.bridge.bridge-nf-call-ip6tables = 1
net.bridge.bridge-nf-call-iptables = 1
EOF

sysctl --system

设置时间同步

yum -y install ntpdate
ntpdate time.windows.com

4. 所有节点安装Docker/kubeadm/kubelet

Kubernetes默认CRI（容器运行时）为Docker，因此先安装Docker。

4.1 安装Docker

每台机器上安装Docker，建议使用18.09版本。

wget https://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo -O /etc/yum.repos.d/docker-ce.repo
yum list docker-ce --showduplicates | sort -r
yum -y install docker-ce-18.09.9-3.el7

设置cgroup驱动，推荐systemd：

 cat > /etc/docker/daemon.json <<EOF
{
  "exec-opts": ["native.cgroupdriver=systemd"],
  "log-driver": "json-file",
  "log-opts": {
    "max-size": "100m"
  },
  "storage-driver": "overlay2"
}
EOF
systemctl enable docker
systemctl start docker

镜像下载加速：

curl -sSL https://get.daocloud.io/daotools/set_mirror.sh | sh -s http://f1361db2.m.daocloud.io

因为追加过cgroup驱动的配置，运行以上命令加载静态加速会使daemon.json的格式不正确，修改为如下

{"registry-mirrors": ["http://f1361db2.m.daocloud.io"],
  "exec-opts": ["native.cgroupdriver=systemd"],
  "log-driver": "json-file",
  "log-opts": {"max-size": "100m"},
  "storage-driver": "overlay2"
}

重新加载
systemctl restart docker

4.2 添加阿里云YUM软件源

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

4.3 安装kubeadm，kubelet和kubectl

由于版本更新频繁，这里指定版本号部署：

yum install -y kubelet-1.16.0 kubeadm-1.16.0 kubectl-1.16.0
systemctl enable kubelet

5. 部署Kubernetes Master

在192.168.140.130（Master）执行。

 kubeadm init \
  --apiserver-advertise-address=192.168.140.130 \
  --image-repository registry.aliyuncs.com/google_containers \
  --kubernetes-version v1.16.0 \
  --service-cidr=10.1.0.0/16 \
  --pod-network-cidr=10.244.0.0/16

由于默认拉取镜像地址k8s.gcr.io国内无法访问，这里指定阿里云镜像仓库地址。

具体创建过程

[root@k8s-master ~]# kubeadm init   --apiserver-advertise-address=192.168.146.130   --image-repository registry.aliyuncs.com/google_containers   --kubernetes-version v1.16.0   --service-cidr=10.1.0.0/16   --pod-network-cidr=10.244.0.0/16
[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 [k8s-master kubernetes kubernetes.default kubernetes.default.svc kubernetes.default.svc.cluster.local] and IPs [10.1.0.1 192.168.146.130]
[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 [192.168.146.130 127.0.0.1 ::1]
[certs] Generating "etcd/peer" certificate and key
[certs] etcd/peer serving cert is signed for DNS names [k8s-master localhost] and IPs [192.168.146.130 127.0.0.1 ::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
[apiclient] All control plane components are healthy after 37.002058 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 k8s-master as control-plane by adding the label "node-role.kubernetes.io/master=''"
[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: z5w3q8.oodwazhy81hs0guy
[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 192.168.146.130:6443 --token z5w3q8.oodwazhy81hs0guy \    #加入node需要验证的token
    --discovery-token-ca-cert-hash sha256:00573b2c69770af26f300158845535faf4fc4be4aab5470b245653a95e85ba0d

使用kubectl工具：

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

[root@k8s-master ~]# kubectl get node
NAME         STATUS   ROLES    AGE    VERSION
k8s-master   Ready    master   4m2s   v1.16.0

6. 安装Pod网络插件（CNI）

这个文件 kube-flannel.yaml 需要注意镜像地址、还有网络地址跟kubeadm init创建的地址要一致pod-network-cidr=10.244.0.0/16

文件预先已设置好，上传到master

https://pan.baidu.com/s/1kYIJXu5J2clmynXbsFZtpg 提取码 bxhp

kubectl apply -f kube-flannel.yaml
kubectl get pods -n kube-system

[root@k8s-master ~]# kubectl get pods -n kube-system
NAME                                 READY   STATUS     RESTARTS   AGE
coredns-58cc8c89f4-2rplz             0/1     Pending    0          3m6s
coredns-58cc8c89f4-rqbpg             0/1     Pending    0          3m6s
etcd-k8s-master                      1/1     Running    0          2m26s
kube-apiserver-k8s-master            1/1     Running    0          2m13s
kube-controller-manager-k8s-master   1/1     Running    0          2m27s
kube-flannel-ds-amd64-l4gcz          0/1     Init:0/1   0          15s
kube-proxy-bhxc2                     1/1     Running    0          3m6s
kube-scheduler-k8s-master            1/1     Running    0          2m13s

7. 加入Kubernetes Node

在192.168.140.131/132（Node）执行。

向集群添加新节点，执行在kubeadm init输出的kubeadm join命令：

kubeadm join 192.168.140.130:6443 --token esce21.q6hetwm8si29qxwn \
    --discovery-token-ca-cert-hash sha256:00603a05805807501d7181c3d60b478788408cfe6cedefedb1f97569708be9c5

[root@k8s-master ~]# kubectl get node
NAME         STATUS   ROLES    AGE     VERSION
k8s-master   Ready    master   8m53s   v1.16.0
k8s-node1    Ready    <none>   3m31s   v1.16.0
k8s-node2    Ready    <none>   91s     v1.16.0

默认token有效期为24小时，当过期之后，该token就不可用了。这时就需要重新创建token，操作如下：

kubeadm token create
kubeadm token list
openssl x509 -pubkey -in /etc/kubernetes/pki/ca.crt | openssl rsa -pubin -outform der 2>/dev/null | openssl dgst -sha256 -hex | sed 's/^.* //'
63bca849e0e01691ae14eab449570284f0c3ddeea590f8da988c07fe2729e924

kubeadm join 192.168.140.130:6443 --discovery-token nuja6n.o3jrhsffiqs9swnu --discovery-token-ca-cert-hash 63bca849e0e01691ae14eab449570284f0c3ddeea590f8da988c07fe2729e924
```

<https://kubernetes.io/docs/reference/setup-tools/kubeadm/kubeadm-join/>

8. 测试kubernetes集群

在Kubernetes集群中创建一个pod，验证是否正常运行：

kubectl create deployment web --image=nginx
kubectl expose deployment web --port=80 --target-port=80 --type=NodePort

[root@k8s-master ~]# kubectl get pods,svc
NAME                      READY   STATUS              RESTARTS   AGE
pod/web-d86c95cc9-9ktfn   0/1     ContainerCreating   0          83s

NAME                 TYPE        CLUSTER-IP    EXTERNAL-IP   PORT(S)        AGE
service/kubernetes   ClusterIP   10.1.0.1      <none>        443/TCP        11m
service/web          NodePort    10.1.87.160   <none>        80:32541/TCP   19s

访问地址：http://NodeIP:Port

确保所有节点都能访问（master、node1、node2）

9. 部署 Dashboard

https://pan.baidu.com/s/1F4fHAas2fDPDgy8h-QS6KA 提取码vb7o

  type: NodePort
  ports:
    - port: 443
      targetPort: 8443
      nodePort: 30001

这个yaml文件增加了一个类型NodePort，端口为30001，其它跟官方yaml一致

kubectl apply -f dashboard.yaml 
kubectl get pods -n kubernetes-dashboard

访问地址：http://NodeIP:30001

创建service account并绑定默认cluster-admin管理员集群角色：

kubectl create serviceaccount dashboard-admin -n kubernetes-dashboard
kubectl create clusterrolebinding dashboard-admin --clusterrole=cluster-admin --serviceaccount=kubernetes-dashboard:dashboard-admin
kubectl describe secrets -n kubernetes-dashboard $(kubectl -n kubernetes-dashboard get secret | awk '/dashboard-admin/{print $1}')

使用输出的token登录Dashboard。