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使用虚拟机安装一个K8s集群

✇Liu Zijian's Blog

因阿里云加速服务调整，镜像加速服务自2024年7月起不再支持，拉取镜像，下载网络插件等操作，需要科学上网访问DockerHub。

安装全过程均使用ROOT权限。

1.安装前准备工作

这里采用3台CentOS虚拟机进行集群安装，安装前需要环境准备：

  1. 使用虚拟机VMware新建一个NAT类型网络(一般都会默认自带，只进行设置即可)，我的起名叫VMnet8，设置VMnet8的子网IP为192.168.228.0，子网掩码为255.255.255.0，网关地址为192.168.228.2，起止IP地址范围192.168.228.3-192.168.228.254，并勾选”将主机虚拟适配器连接到此网络”为物理机分配IP地址，一般会分配192.168.228.1给物理机。

  2. VMware安装3台Linux虚拟机，可以安装一台，然后完整克隆，这里我采用的安装镜像版本是CentOS-7-x86_64-Minimal-2009，安装完成后，设置网络为VMnet8，将IP获取方式由DHCP修改为静态，并将IP地址分别设置为192.168.228.131，192.168.228.132，192.168.228.133，再分别设置网关，子网掩码，DNS，MAC地址，并保证MAC地址互相不重复。

系统下载地址 https://mirrors.aliyun.com/centos/7/isos/x86_64/

2.安装docker

K8s是个容器编排工具，需要容器环境，这里容器环境采用Docker，每台机器都要安装docker环境

3.安装K8s集群

3.1 安装条件

  • 兼容的Linux发行版（Ubuntu，CentOS等等）
  • 机器需要2GB内存，CPU2核及以上
  • 集群中机器网络彼此互通
  • 集群中不可有重复的主机名
  • 集群中不可有重复的MAC地址

3.2 安装规划

主节点一台机器，从节点两台机器

  • 主节点master

    主机名：k8s131， IP：192.168.228.131

  • 从节点node

    主机名：k8s132， IP：192.168.228.132
    主机名：k8s133， IP：192.168.228.133

3.3 安装前设置

三台机器都要进行设置。

1.设置主机名

在对应IP地址的机器上分别设置主机名为k8s131，k8s132，k8s133

hostnamectl set-hostname xxx

执行后，检查是否都设置好了

hostname

会话exit退出后重连shell，就会看到shell的计算机名已经变成了自己设置的计算机名root@k8s131

Last login: Thu Nov 21 17:47:02 2024 from 192.168.228.1[root@k8s133 ~]#

2.关闭交换分区

使用free -m命令，可以查看交换分区情况，安装K8s前，需要关闭交换分区，且永久关闭

[root@localhost ~]# free -m              total        used        free      shared  buff/cache   availableMem:           1819         309        1166           9         342        1360Swap:          2047           0        2047

执行命令，永久关闭交换分区(将Swap设置为 0 0 0)

swapoff -a  sed -ri 's/.*swap.*/#&/' /etc/fstab

3.禁用，并永久禁用SELinux

sudo setenforce 0sudo sed -i 's/^SELINUX=enforcing$/SELINUX=permissive/' /etc/selinux/config

4.设置允许iptables检查桥接流量

将IPV6流量桥接到IPV4网卡上，是K8s官方要求的做法

cat <<EOF | sudo tee /etc/modules-load.d/k8s.confbr_netfilterEOFcat <<EOF | sudo tee /etc/sysctl.d/k8s.confnet.bridge.bridge-nf-call-ip6tables = 1net.bridge.bridge-nf-call-iptables = 1EOFsudo sysctl --system

5.关闭防火墙

CentOS7默认打开防火墙firewalld，3台都需要关闭firewalld

systemctl stop firewalldsystemctl disable firewalld

3.4 安装K8s组件

1.安装kubelet、kubeadm、kubectl

首先添加k8s软件包的yum源到三台机器

cat <<EOF | sudo tee /etc/yum.repos.d/kubernetes.repo[kubernetes]name=Kubernetesbaseurl=http://mirrors.aliyun.com/kubernetes/yum/repos/kubernetes-el7-x86_64enabled=1gpgcheck=0repo_gpgcheck=0gpgkey=http://mirrors.aliyun.com/kubernetes/yum/doc/yum-key.gpg   http://mirrors.aliyun.com/kubernetes/yum/doc/rpm-package-key.gpgexclude=kubelet kubeadm kubectlEOF

三台机器依次执行安装命令

sudo yum install -y kubelet-1.20.9 kubeadm-1.20.9 kubectl-1.20.9 --disableexcludes=kubernetes

三台机器都启动kubelet，并设置开机启动

sudo systemctl enable --now kubelet

不停执行systemctl status kubelet会发现服务一直处于闪断状态，因为kubelet一直在等待

3.5 初始化主节点

使用kubeadm引导集群，初始化主节点。

1.首先所有机器都要先下载需要的镜像

docker pull registry.k8s.io/kube-apiserver:v1.20.9docker pull registry.k8s.io/kube-proxy:v1.20.9docker pull registry.k8s.io/kube-controller-manager:v1.20.9docker pull registry.k8s.io/kube-scheduler:v1.20.9docker pull registry.k8s.io/coredns:1.7.0docker pull registry.k8s.io/etcd:3.4.13-0docker pull registry.k8s.io/pause:3.2

下载完成后docker images验证

2.设置主节点域名映射

3台机器都必须添加master节点(又叫集群的入口节点)的域名映射，IP按实际情况修改。

echo "192.168.228.131  cluster-endpoint" >> /etc/hosts

3.初始化主节点

在主节点所在机器上执行命令，初始化主节点

参数解释

  • --service-cidr, --pod-network-cidr 两项设置的网络范围不能重叠，也不能同服务器所在网络范围重叠。
  • --apiserver-advertise-address改成自己主节点的IP。
  • --control-plane-endpoint改为自己设置的主节点域名。

命令 

kubeadm init \--image-repository registry.k8s.io \--apiserver-advertise-address=192.168.228.131 \--control-plane-endpoint=cluster-endpoint \--kubernetes-version=v1.20.9 \--service-cidr=10.96.0.0/16 \--pod-network-cidr=192.168.23.0/24

等待初始化完成后，终端输出提示成功，说明初始化完成。输出的内容需要复制保存备用。

[root@k8s131 ~]# kubeadm init \> --image-repository registry.k8s.io \> --apiserver-advertise-address=192.168.228.131 \> --control-plane-endpoint=cluster-endpoint \> --kubernetes-version=v1.20.9 \> --service-cidr=10.96.0.0/16 \> --pod-network-cidr=192.168.23.0/24 [init] Using Kubernetes version: v1.20.9[preflight] Running pre-flight checks[WARNING Firewalld]: firewalld is active, please ensure ports [6443 10250] are open or your cluster may not function correctly[WARNING IsDockerSystemdCheck]: detected "cgroupfs" as the Docker cgroup driver. The recommended driver is "systemd". Please follow the guide at https://kubernetes.io/docs/setup/cri/[WARNING SystemVerification]: this Docker version is not on the list of validated versions: 20.10.7. Latest validated version: 19.03[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 [cluster-endpoint k8s131 kubernetes kubernetes.default kubernetes.default.svc kubernetes.default.svc.cluster.local] and IPs [10.96.0.1 192.168.228.131][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 [k8s131 localhost] and IPs [192.168.228.131 127.0.0.1 ::1][certs] Generating "etcd/peer" certificate and key[certs] etcd/peer serving cert is signed for DNS names [k8s131 localhost] and IPs [192.168.228.131 127.0.0.1 ::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[apiclient] All control plane components are healthy after 14.007116 seconds[upload-config] Storing the configuration used in ConfigMap "kubeadm-config" in the "kube-system" Namespace[kubelet] Creating a ConfigMap "kubelet-config-1.20" 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 k8s131 as control-plane by adding the labels "node-role.kubernetes.io/master=''" and "node-role.kubernetes.io/control-plane='' (deprecated)"[mark-control-plane] Marking the node k8s131 as control-plane by adding the taints [node-role.kubernetes.io/master:NoSchedule][bootstrap-token] Using token: 4qn4kj.52saric9a3vqnk1w[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-proxyYour 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/configAlternatively, if you are the root user, you can run:  export KUBECONFIG=/etc/kubernetes/admin.confYou 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/You can now join any number of control-plane nodes by copying certificate authoritiesand service account keys on each node and then running the following as root:  kubeadm join cluster-endpoint:6443 --token 4qn4kj.52saric9a3vqnk1w \    --discovery-token-ca-cert-hash sha256:7f12181600006aeb62fb38bcb82582809a9ad1911e49065f1fd13f9c68c95774 \    --control-plane Then you can join any number of worker nodes by running the following on each as root:kubeadm join cluster-endpoint:6443 --token 4qn4kj.52saric9a3vqnk1w \    --discovery-token-ca-cert-hash sha256:7f12181600006aeb62fb38bcb82582809a9ad1911e49065f1fd13f9c68c95774

4.配置文件目录

按照上述的输出提示“To start using your cluster, you need to run the following as a regular user” 还需要需要在主节点执行下面的命令

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

5.部署网络插件

按照上述的输出提示 You should now deploy a pod network to the cluster. Run “kubectl apply -f [podnetwork].yaml”，接下来还需要部署一个pod网络插件到master节点上。

输入命令kubectl get nodes -A，测试下主节点状态，返回NotReady是因为还没有部署网络插件。

[root@k8s131 ~]# kubectl get nodes -ANAME     STATUS     ROLES                  AGE    VERSIONk8s131   NotReady   control-plane,master   5h5m   v1.20.9

k8s支持多种网络插件，例如calico，安装前要先将它的编排文件下载到本地目录

curl https://docs.projectcalico.org/v3.20/manifests/calico.yaml -O

配置文件中找到以下内容

# - name: CALICO_IPV4POOL_CIDR#   value: "192.168.0.0/16"

将默认的192.168.0.0/16修改为--pod-network-cidr=指定的地址192.168.23.0/24，并解除注释

- name: CALICO_IPV4POOL_CIDR  value: "192.168.23.0/24"

在主节点执行命令，部署网络插件calico，部署过程需要联网下载镜像

kubectl apply -f calico.yaml
[root@k8s131 opt]# kubectl apply -f calico.yaml configmap/calico-config createdcustomresourcedefinition.apiextensions.k8s.io/bgpconfigurations.crd.projectcalico.org createdcustomresourcedefinition.apiextensions.k8s.io/bgppeers.crd.projectcalico.org createdcustomresourcedefinition.apiextensions.k8s.io/blockaffinities.crd.projectcalico.org createdcustomresourcedefinition.apiextensions.k8s.io/clusterinformations.crd.projectcalico.org createdcustomresourcedefinition.apiextensions.k8s.io/felixconfigurations.crd.projectcalico.org createdcustomresourcedefinition.apiextensions.k8s.io/globalnetworkpolicies.crd.projectcalico.org createdcustomresourcedefinition.apiextensions.k8s.io/globalnetworksets.crd.projectcalico.org createdcustomresourcedefinition.apiextensions.k8s.io/hostendpoints.crd.projectcalico.org createdcustomresourcedefinition.apiextensions.k8s.io/ipamblocks.crd.projectcalico.org createdcustomresourcedefinition.apiextensions.k8s.io/ipamconfigs.crd.projectcalico.org createdcustomresourcedefinition.apiextensions.k8s.io/ipamhandles.crd.projectcalico.org createdcustomresourcedefinition.apiextensions.k8s.io/ippools.crd.projectcalico.org createdcustomresourcedefinition.apiextensions.k8s.io/kubecontrollersconfigurations.crd.projectcalico.org createdcustomresourcedefinition.apiextensions.k8s.io/networkpolicies.crd.projectcalico.org createdcustomresourcedefinition.apiextensions.k8s.io/networksets.crd.projectcalico.org createdclusterrole.rbac.authorization.k8s.io/calico-kube-controllers createdclusterrolebinding.rbac.authorization.k8s.io/calico-kube-controllers createdclusterrole.rbac.authorization.k8s.io/calico-node createdclusterrolebinding.rbac.authorization.k8s.io/calico-node createddaemonset.apps/calico-node createdserviceaccount/calico-node createddeployment.apps/calico-kube-controllers createdserviceaccount/calico-kube-controllers createdpoddisruptionbudget.policy/calico-kube-controllers created

输入kubectl get pods -A查看网络插件pod部署情况

状态为ContainerCreating，Init说明正在下载部署

[root@k8s131 opt]# kubectl get pods -ANAMESPACE     NAME                                       READY   STATUS              RESTARTS   AGEkube-system   calico-kube-controllers-577f77cb5c-wpxh7   0/1     ContainerCreating   0          21mkube-system   calico-node-7wb4z                          0/1     Init:2/3            0          9m3skube-system   coredns-76c6f6bbc9-4q5f9                   0/1     ContainerCreating   0          5h41mkube-system   coredns-76c6f6bbc9-nkdcl                   0/1     ContainerCreating   0          5h41mkube-system   etcd-k8s131                                1/1     Running             1          5h41mkube-system   kube-apiserver-k8s131                      1/1     Running             1          5h41mkube-system   kube-controller-manager-k8s131             1/1     Running             1          5h41mkube-system   kube-proxy-nt5jf                           1/1     Running             1          5h41mkube-system   kube-scheduler-k8s131                      1/1     Running             1          5h41m

完成后状态均为Running

[root@k8s131 opt]# kubectl get pods -ANAMESPACE     NAME                                       READY   STATUS    RESTARTS   AGEkube-system   calico-kube-controllers-577f77cb5c-wpxh7   1/1     Running   0          24mkube-system   calico-node-7wb4z                          1/1     Running   0          12mkube-system   coredns-76c6f6bbc9-4q5f9                   1/1     Running   0          5h44mkube-system   coredns-76c6f6bbc9-nkdcl                   1/1     Running   0          5h44mkube-system   etcd-k8s131                                1/1     Running   1          5h45mkube-system   kube-apiserver-k8s131                      1/1     Running   1          5h45mkube-system   kube-controller-manager-k8s131             1/1     Running   1          5h45mkube-system   kube-proxy-nt5jf                           1/1     Running   1          5h44mkube-system   kube-scheduler-k8s131                      1/1     Running   1          5h45m

再次输入命令kubectl get nodes -A测试主节点状态，已经变为Ready，准备就绪，网络插件到此部署完成。

[root@k8s131 opt]# kubectl get nodes -ANAME     STATUS   ROLES                  AGE     VERSIONk8s131   Ready    control-plane,master   5h53m   v1.20.9

主节点至此初始化完成。

3.6 从节点加入集群

从节点加入集群的命令，在初始化主节点命令输出的内容中就有，在之前复制的输出内容中找到Then you can join any number of worker nodes by running the following on each as root:，并找到它下面的一行命令在每个从节点执行，该命令24小时内有效

kubeadm join cluster-endpoint:6443 --token 4qn4kj.52saric9a3vqnk1w \    --discovery-token-ca-cert-hash sha256:7f12181600006aeb62fb38bcb82582809a9ad1911e49065f1fd13f9c68c95774

如果令牌忘记了，或者超过了24小时，在master节点上执行下面的命令，生成新的令牌

kubeadm token create --print-join-command

在两个从节点执行这个命令，执行后，以下提示，说明加入成功

[root@k8s132 ~]# kubeadm join cluster-endpoint:6443 --token bjme49.uhg7ubgjn2m16b76     --discovery-token-ca-cert-hash sha256:7f12181600006aeb62fb38bcb82582809a9ad1911e49065f1fd13f9c68c95774[preflight] Running pre-flight checks[WARNING IsDockerSystemdCheck]: detected "cgroupfs" as the Docker cgroup driver. The recommended driver is "systemd". Please follow the guide at https://kubernetes.io/docs/setup/cri/[WARNING SystemVerification]: this Docker version is not on the list of validated versions: 20.10.7. Latest validated version: 19.03[WARNING Hostname]: hostname "k8s132" could not be reached[WARNING Hostname]: hostname "k8s132": lookup k8s132 on 192.168.228.2:53: server misbehaving[preflight] Reading configuration from the cluster...[preflight] FYI: You can look at this config file with 'kubectl -n kube-system get cm kubeadm-config -o yaml'[kubelet-start] Writing kubelet configuration to file "/var/lib/kubelet/config.yaml"[kubelet-start] Writing kubelet environment file with flags to file "/var/lib/kubelet/kubeadm-flags.env"[kubelet-start] Starting the kubelet[kubelet-start] Waiting for the kubelet to perform the TLS Bootstrap...This node has joined the cluster:* Certificate signing request was sent to apiserver and a response was received.* The Kubelet was informed of the new secure connection details.Run 'kubectl get nodes' on the control-plane to see this node join the cluster.

回到主节点执行命令kubectl get nodes -A，查看节点状态，可以看到两个从节点了，但是状态是NotReady，此时执行kubectl get pods -A查看pods状态，发现是因为从节点的网络插件未初始化成功完成导致，此时需要耐心等待网络插件加载完成，以我的经验来说加载网络插件需要下载很久。

管理集群要靠主节点，kubectl命令只能在主节点执行

[root@k8s131 ~]# kubectl get nodes -ANAME     STATUS     ROLES                  AGE     VERSIONk8s131   Ready      control-plane,master   2d23h   v1.20.9k8s132   NotReady   <none>                 6m49s   v1.20.9k8s133   NotReady   <none>                 6m41s   v1.20.9
[root@k8s131 ~]# kubectl get pods -ANAMESPACE     NAME                                       READY   STATUS                  RESTARTS   AGEkube-system   calico-kube-controllers-577f77cb5c-wpxh7   1/1     Running                 1          2d18hkube-system   calico-node-7wb4z                          1/1     Running                 1          2d18hkube-system   calico-node-plcdp                          0/1     Init:ImagePullBackOff   0          8m22skube-system   calico-node-zwmrg                          0/1     Init:ImagePullBackOff   0          8m30skube-system   coredns-76c6f6bbc9-4q5f9                   1/1     Running                 1          2d23hkube-system   coredns-76c6f6bbc9-nkdcl                   1/1     Running                 1          2d23hkube-system   etcd-k8s131                                1/1     Running                 2          2d23hkube-system   kube-apiserver-k8s131                      1/1     Running                 2          2d23hkube-system   kube-controller-manager-k8s131             1/1     Running                 2          2d23hkube-system   kube-proxy-flrq9                           1/1     Running                 0          8m22skube-system   kube-proxy-nt5jf                           1/1     Running                 2          2d23hkube-system   kube-proxy-tcrjv                           1/1     Running                 0          8m30skube-system   kube-scheduler-k8s131                      1/1     Running                 2          2d23h

等到kubectl get pods -A全部变为Running，再次测试kubectl get nodes -A

[root@k8s131 ~]# kubectl get nodes -ANAME     STATUS   ROLES                  AGE   VERSIONk8s131   Ready    control-plane,master   3d    v1.20.9k8s132   Ready    <none>                 23m   v1.20.9k8s133   Ready    <none>                 22m   v1.20.9

所有节点状态都是Ready，至此，两个从节点加入了K8s集群并进入就绪状态，整个K8s集群安装完成！

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