Docker 与 K8S学习笔记（二十三）—— Kubernetes集群搭建

小伙伴们，好久不见，这几个月实在太忙，所以一直没有更新，今天刚好有空，咱们继续k8s的学习，由于我们后面需要深入学习Pod的调度，所以我们原先使用MiniKube搭建的实验环境就不能满足我们的需求了，我们这一节将使用kubeadm搭建Kubernets集群。

一、虚拟机创建

我们的集群包含三个节点kubevm1、kubevm2、kubevm3，其中kubevm1作为Master

我们首先需要使用Virtualbox创建一个虚拟机，步骤如下：

1、新建虚拟机

我们设置内存2G，硬盘20G，CPU 2核，在光驱设置中选择已经下好的Centos镜像。

设置网络为【桥接网卡】

2、安装系统

启动虚拟机，进入安装界面，根据安装向导：

• 设置时区；

• 选择安装磁盘并分区（直接自动分区即可）；
• 安装模式选【Minimal Install】，附加软件全选；
• "NETWORK & HOST NAME"中打开OnBoot，主机名如果不在这里设置，在安装完系统后可以通过“hostnamectl”命令设置；
• 安装过程中可以设置root用户密码或者添加新用户，我们这里图省事就直接用root账户了。

等待系统安装完毕后，重起虚拟机，为了操作方便，我们使用宿主机的终端ssh到虚拟机。

PS：由于是最小化安装，是没有ifconfig命令的，所以我们可以通过ip addr获取到虚拟机IP，然后再通过ssh登陆。

3、系统设置

1）禁用SELinux

• 临时关闭：命令行执行 setenforce 0

• 永久关闭：修改/etc/selinux/config文件，将SELINUX=enforcing改为SELINUX=disabled

2）关闭防火墙

systemctl disable firewalld && systemctl stop firewalld

3）关闭交换分区

swapoff -a && sed -i '/ swap / s/^/#/' /etc/fstab

4）更改iptables设置

echo 1 > /proc/sys/net/bridge/bridge-nf-call-iptables

PS：如果提示找不到bridge-nf-call-iptables，可执行一下命令：

modprobe br_netfilter

二、安装Docker

yum install docker -y

三、安装Kubernetes

1、设置yum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

2、添加docker镜像

vim /etc/docker/daemon.json
添加如下内容：
"registry-mirrors": ["https://registry.docker-cn.co"]

3、安装kubectl、kubeadm、kubelet

yum install -y kubelet-1.19.16 kubeadm-1.19.16 kubectl-1.19.16

4、启动docker和kubelet

systemctl enable docker && systemctl start docker
systemctl enable kubelet && systemctl start kubelet

四、Kubernetes集群安装与配置

1、复制虚拟机并配置hosts

我们首先复制出两个虚拟机，并分别修改其hostname为kubevm2和kubevm3。

hostnamectl set-hostnam xxx

将三台虚拟机的地址写入到宿主机和每一台虚拟机的hosts文件中：

vim /etc/hosts

192.168.0.187   kubevm1
192.168.0.185   kubevm2
192.168.0.184   kubevm3

2、初始化master（kubevm1）

在kubevm1上执行kubeadm init

[root@kubevm1 ~]# kubeadm init --apiserver-advertise-address=192.168.56.120 --image-repository=registry.aliyuncs.com/google_containers --kubernetes-version=v1.19.16 --service-cidr=10.1.0.0/16 --pod-network-cidr=10.244.0.0/16
W0518 23:27:14.470037    2551 configset.go:348] WARNING: kubeadm cannot validate component configs for API groups [kubelet.config.k8s.io kubeproxy.config.k8s.io]
[init] Using Kubernetes version: v1.19.16
[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'
[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 [kubernetes kubernetes.default kubernetes.default.svc kubernetes.default.svc.cluster.local kubevm1] and IPs [10.1.0.1 192.168.56.120]
[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 [kubevm1 localhost] and IPs [192.168.56.120 127.0.0.1 ::1]
[certs] Generating "etcd/peer" certificate and key
[certs] etcd/peer serving cert is signed for DNS names [kubevm1 localhost] and IPs [192.168.56.120 127.0.0.1 ::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
[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] Starting the kubelet
[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 43.002951 seconds
[upload-config] Storing the configuration used in ConfigMap "kubeadm-config" in the "kube-system" Namespace
[kubelet] Creating a ConfigMap "kubelet-config-1.19" 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 kubevm1 as control-plane by adding the label "node-role.kubernetes.io/master=''"
[mark-control-plane] Marking the node kubevm1 as control-plane by adding the taints [node-role.kubernetes.io/master:NoSchedule]
[bootstrap-token] Using token: wribbh.31c6e1tnddpnpwn9
[bootstrap-token] Configuring bootstrap tokens, cluster-info ConfigMap, RBAC Roles
[bootstrap-token] configured RBAC rules to allow Node Bootstrap tokens to get nodes
[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
[kubelet-finalize] Updating "/etc/kubernetes/kubelet.conf" to point to a rotatable kubelet client certificate and key
[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 192.168.56.120:6443 --token wribbh.31c6e1tnddpnpwn9 \
    --discovery-token-ca-cert-hash sha256:1804e7ee43d7469839b3f5fdbf2c57f5d53eee1da6bc40c59a1b04fce6edddd5

接下来我们执行以下命令，这样我们就可以使用kubectl管理集群了：

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

我们先查看下当前集群各个组件状态：

[root@kubevm1 ~]# kubectl get pods,svc -n kube-system
NAME                                  READY   STATUS    RESTARTS   AGE
pod/coredns-6d56c8448f-jf9gg          0/1     Pending   0          2m4s
pod/coredns-6d56c8448f-m2cdp          0/1     Pending   0          2m3s
pod/etcd-kubevm1                      1/1     Running   0          2m17s
pod/kube-apiserver-kubevm1            1/1     Running   0          2m17s
pod/kube-controller-manager-kubevm1   1/1     Running   0          2m17s
pod/kube-proxy-rv7g4                  1/1     Running   0          2m4s
pod/kube-scheduler-kubevm1            1/1     Running   0          2m17s

NAME               TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)                  AGE
service/kube-dns   ClusterIP   10.1.0.10    <none>        53/UDP,53/TCP,9153/TCP   2m19s

我们发现coredns都处于NotReady状态，这是因为我们还没有安装网络组件。

3、安装网络插件

下载fannel的yaml配置文件：

wget https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml

这里确认下yaml中Network是否与前面执行kubeadm init时--pod-network-cidr参数的值一致。

kubectl apply -f kube-flannel.yml

等待一会儿，我们可以看到集群中网络服务对应的Pod都ok了：

[root@kubevm1 ~]# kubectl get pods,svc -n kube-system
NAME                                  READY   STATUS    RESTARTS   AGE
pod/coredns-6d56c8448f-jf9gg          1/1     Running   0          28m
pod/coredns-6d56c8448f-m2cdp          1/1     Running   0          28m
pod/etcd-kubevm1                      1/1     Running   0          28m
pod/kube-apiserver-kubevm1            1/1     Running   0          28m
pod/kube-controller-manager-kubevm1   1/1     Running   0          28m
pod/kube-flannel-ds-td89l             1/1     Running   0          13m
pod/kube-proxy-rv7g4                  1/1     Running   0          28m
pod/kube-scheduler-kubevm1            1/1     Running   0          28m

NAME               TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)                  AGE
service/kube-dns   ClusterIP   10.1.0.10    <none>        53/UDP,53/TCP,9153/TCP   28m

4、注册Node

在kubevm2、kubevm3中执行以下命令，注册到master：

kubeadm join 192.168.56.120:6443 --token wribbh.31c6e1tnddpnpwn9 \
    --discovery-token-ca-cert-hash sha256:1804e7ee43d7469839b3f5fdbf2c57f5d53eee1da6bc40c59a1b04fce6edddd5

注册后我们使用kubectl get node查看一下：

[root@kubevm1 ~]# kubectl get nodes
NAME      STATUS   ROLES    AGE   VERSION
kubevm1   Ready    master   46m   v1.19.16
kubevm2   Ready    <none>   15m   v1.19.16
kubevm3   Ready    <none>   14m   v1.19.16

ok，至此整个集群搭建完成。