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Docker 与 K8S学习笔记之Kubernetes集群搭建

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=
enabled=1
gpgcheck=0
repo_gpgcheck=0
gpgkey= 
 EOF   

2、添加docker镜像

  vim  /etc/docker/daemon.json
添加如下内容:
"registry-mirrors": ["#34;]  

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  Pod s 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:
  

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    

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。

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