【k8s实践】使用kubeadm搭建kubernetes集群
文章目录
环境要求
3台Linux虚拟机, 能联网, 我使用的发行版是Rocky Linux 9.4
最低配置: 2CPU, 2G内存, 20G硬盘
3台虚拟机的IP和主机名如下
k8s-master 192.168.52.200 (k8s主节点)
k8s-node1 192.168.52.201 (k8s从节点1)
k8s-node2 192.168.52.202 (k8s从节点2)
0. 准备操作
关闭防火墙
systemctl stop firewalld
systemctl disable firewalld
关闭SELINUX
setenforce 0
sed --follow-symlinks -i "s/SELINUX=enforcing/SELINUX=disabled/g" /etc/selinux/config
修改主机名
k8s主节点执行
hostnamectl set-hostname k8s-master
从节点1执行
hostnamectl set-hostname k8s-node1
从节点2执行
hostnamectl set-hostname k8s-node2
修改hosts文件
修改所有机器的/etc/hosts文件, 添加三台虚拟机的IP和主机名
192.168.52.200 k8s-master
192.168.52.201 k8s-node1
192.168.52.202 k8s-node2
禁用交换分区
kubelet默认行为是在节点上检测到交换内存时无法启动，所以这里先禁用交换分区。临时禁用交换分区方法:
swapoff -a
如需要永久禁用交换分区，修改/etc/fstab, 删除swap分区那一行的配置。
加载内核模块, 再设置内核参数
临时加载内核模块
modprobe ip_vs_rr
modprobe br_netfilter
每次启动自动加载
vim /etc/modules-load.d/k8s.conf
overlay
br_netfilter
再设置内核参数
cat <<EOF | tee /etc/sysctl.d/k8s.conf
net.bridge.bridge-nf-call-ip6tables = 1
net.bridge.bridge-nf-call-iptables = 1
net.ipv4.ip_forward = 1
EOF
sysctl -p /etc/sysctl.d/k8s.conf
1. 安装containerd, kubeadm, kubelet, kubectl, calico
国内机器需要更换YUM国内源
sed -e 's|^mirrorlist=|#mirrorlist=|g' \
-e 's|^#baseurl=http://dl.rockylinux.org/$contentdir|baseurl=https://mirrors.aliyun.com/rockylinux|g' \
-i.bak \
/etc/yum.repos.d/[Rr]ocky-*.repo
dnf makecache
所有机器安装containerd
dnf config-manager --add-repo https://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo # 国内用阿里源
#dnf config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo
dnf install -y containerd
配置containerd
containerd config default > /etc/containerd/config.toml
再修改/etc/containerd/config.toml
- 把SystemdCGroup的值改成true
- 把sandbox_image改为
registry.aliyuncs.com/google_containers/pause:3.9(国内用户需要做这一步，把镜像换成阿里的)
启动containerd
systemctl daemon-reload
systemctl enable --now containerd
查看containerd版本
# ctr version
Client:
Version: 1.7.24
# runc -v
runc version 1.2.2
所有机器安装kubeadm, kubelet, kubectl
先添加k8s的repo
cat <<EOF > /etc/yum.repos.d/kubernetes.repo
[kubernetes]
name=Kubernetes
baseurl=https://mirrors.aliyun.com/kubernetes/yum/repos/kubernetes-el7-x86_64/
enabled=1
gpgcheck=1
repo_gpgcheck=1
gpgkey=https://mirrors.aliyun.com/kubernetes/yum/doc/yum-key.gpg https://mirrors.aliyun.com/kubernetes/yum/doc/rpm-package-key.gpg
EOF
再通过yum安装kubelet, kubeadm, kubectl
yum install -y kubelet kubeadm kubectl
systemctl enable --now kubelet
查看kubelet, kubeadm, kubectl版本
kubeadm version
kubeadm version: &version.Info{Major:"1", Minor:"28", GitVersion:"v1.28.2", GitCommit:"89a4ea3e1e4ddd7f7572286090359983e0387b2f", GitTreeState:"clean", BuildDate:"2023-09-13T09:34:32Z", GoVersion:"go1.20.8", Compiler:"gc", Platform:"linux/amd64"}
[root@k8s-master yum.repos.d]# kubectl version
Client Version: v1.28.2
Kustomize Version: v5.0.4-0.20230601165947-6ce0bf390ce3
The connection to the server localhost:8080 was refused - did you specify the right host or port?
[root@k8s-master yum.repos.d]# kubelet --version
Kubernetes v1.28.2
说明: kubelet现在每隔几秒就会重启，它陷入了一个等待 kubeadm 指令的死循环, 这是符合预期的。 接下来需要在主节点执行kubeadm init，初始化k8s集群
2. 初始化k8s集群
在主节点执行kubeadm init
kubeadm init --apiserver-advertise-address 192.168.52.200 \
--image-repository registry.aliyuncs.com/google_containers \
--kubernetes-version v1.28.2 \
--pod-network-cidr=198.18.0.0/16
参数说明:
–apiserver-advertise-address：监听地址，填主节点IP
–image-repository：国内用户需指定镜像地址为阿里云的，默认是海外镜像你无法访问。
–kubernetes-version：指定kubernetes的版本
–pod-network-cidr=198.18.0.0/16 (这个cidr表示Pod的IP地址范围，根据你的网络环境自定义，不能和其他IP发生冲突即可)
执行时间较长，耐心等几分钟。 执行成功后，会打印如下内容，提示你下一步怎么做
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
Alternatively, if you are the root user, you can run:
export KUBECONFIG=/etc/kubernetes/admin.conf
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 192.168.52.200:6443 --token zk8fth.5psohqfk9lomq0tw \
--discovery-token-ca-cert-hash sha256:f32851bb6a86cc7f0a394f1d77e1db5b217cde1b0f40909ee3916959519173f7
我使用的是root用户，参照上面的提示，只需export环境变量KUBECONFIG，操作如下：
编辑/etc/profile，结尾添加一行
export KUBECONFIG=/etc/kubernetes/admin.conf
使环境变量立即生效
source /etc/profile
此时，kubectl已经可以查到如下pod, 但coredns pod运行不成功。下一步需要在主节点上安装网络插件
kubectl get pods -A
NAMESPACE NAME READY STATUS RESTARTS AGE
kube-system coredns-66f779496c-8ctsc 0/1 Pending 0 3m11s
kube-system coredns-66f779496c-hx76v 0/1 Pending 0 3m11s
kube-system etcd-k8s-master 1/1 Running 0 3m24s
kube-system kube-apiserver-k8s-master 1/1 Running 0 3m24s
kube-system kube-controller-manager-k8s-master 1/1 Running 0 3m24s
kube-system kube-proxy-89c9k 1/1 Running 0 3m11s
kube-system kube-scheduler-k8s-master 1/1 Running 0 3m24s
3. 在主节点安装calico网络插件
安装网络插件，可以选择calico或者flannel，我这里选calico，安装最新版本
calico安装，我参考了官方文档: https://docs.tigera.io/calico/latest/getting-started/kubernetes/quickstart
1、Install the Tigera Calico operator and custom resource definitions.
yum install -y wget
wget https://raw.githubusercontent.com/projectcalico/calico/v3.29.1/manifests/tigera-operator.yaml
kubectl create -f tigera-operator.yaml
2、Install Calico by creating the necessary custom resource.
wget https://raw.githubusercontent.com/projectcalico/calico/v3.29.1/manifests/custom-resources.yaml
修改custom-resources.yaml, 把cidr改成198.18.0.0/16
kubectl create -f custom-resources.yaml
3、Confirm that all of the pods are running with the following command.
watch kubectl get pods -n calico-system
Wait until each pod has the STATUS of Running.
4、Remove the taints on the control plane so that you can schedule pods on it.
kubectl taint nodes --all node-role.kubernetes.io/control-plane-
node/k8s-master untainted
5、 Confirm that you now have a node in your cluster with the following command.
kubectl get nodes -o wide
NAME STATUS ROLES AGE VERSION INTERNAL-IP EXTERNAL-IP OS-IMAGE KERNEL-VERSION CONTAINER-RUNTIME
k8s-master Ready control-plane 5h16m v1.28.2 10.206.216.96 <none> Rocky Linux 9.4 (Blue Onyx) 5.14.0-427.13.1.el9_4.x86_64 containerd://1.7.24
如果是国内用户，最常见问题是Pod启动失败，无法拉取镜像。 你可以用kubectl describe查看启动日志，获取拉取失败的镜像信息，然后从国内源拉取，再改一下tag即可
calico安装需要的镜像如下:
[root@k8s-master ~]# ctr -n k8s.io image list | awk '{print $1}'
REF
docker.io/calico/apiserver:v3.29.1
docker.io/calico/cni:v3.29.1
docker.io/calico/csi:v3.29.1
docker.io/calico/kube-controllers:v3.29.1
docker.io/calico/node-driver-registrar:v3.29.1
docker.io/calico/node:v3.29.1
docker.io/calico/pod2daemon-flexvol:v3.29.1
docker.io/calico/typha:v3.29.1
quay.io/tigera/operator:v1.36.2
国内镜像站: https://docker.aityp.com
例: 手动拉取docker.io/calico/kube-controllers:v3.29.1镜像，再打tag
ctr -n k8s.io images pull swr.cn-north-4.myhuaweicloud.com/ddn-k8s/docker.io/calico/kube-controllers:v3.29.1
ctr -n k8s.io images tag swr.cn-north-4.myhuaweicloud.com/ddn-k8s/docker.io/calico/kube-controllers:v3.29.1 docker.io/calico/kube-controllers:v3.29.1
安装calicoctl
calicoctl安装，参考了官方文档: https://docs.tigera.io/calico/latest/operations/calicoctl/install
curl -L https://github.com/projectcalico/calico/releases/download/v3.29.1/calicoctl-linux-amd64 -o calicoctl
chmod +x ./calicoctl
cp calicoctl /usr/bin/
查看calico Pod是否创建成功
kubectl get pods -A
NAMESPACE NAME READY STATUS RESTARTS AGE
kube-system calico-kube-controllers-658d97c59c-gftzg 1/1 Running 0 12m
kube-system calico-node-x7dhl 1/1 Running 0 12m
kube-system coredns-66f779496c-8ctsc 1/1 Running 0 62m
kube-system coredns-66f779496c-hx76v 1/1 Running 0 62m
kube-system etcd-k8s-master 1/1 Running 0 62m
kube-system kube-apiserver-k8s-master 1/1 Running 0 62m
kube-system kube-controller-manager-k8s-master 1/1 Running 0 62m
kube-system kube-proxy-89c9k 1/1 Running 0 62m
kube-system kube-scheduler-k8s-master 1/1 Running 0 62m
此时，通过calicoctl可以查到主节点k8s-master
# calicoctl node status
Calico process is running.
IPv4 BGP status
No IPv4 peers found.
IPv6 BGP status
No IPv6 peers found.
# calicoctl get nodes
NAME
k8s-master
4. 把其他两个从节点加入集群
先在Master节点上获取token
kubeadm token list | awk '{print $1}'
TOKEN
zk8fth.5psohqfk9lomq0tw
默认token 24小时内过期，如果过期了，可以在主节点上重新创建新token
kubeadm token create
再从主节点上获取–discovery-token-ca-cert-hash的值
openssl x509 -pubkey -in /etc/kubernetes/pki/ca.crt | openssl rsa -pubin -outform der 2>/dev/null | \
openssl dgst -sha256 -hex | sed 's/^.* //'
f32851bb6a86cc7f0a394f1d77e1db5b217cde1b0f40909ee3916959519173f7
最后,在两个从节点执行kubeadm join命令，将从节点加入集群:
kubeadm join --token zk8fth.5psohqfk9lomq0tw \
192.168.52.200:6443 \
--discovery-token-ca-cert-hash sha256:f32851bb6a86cc7f0a394f1d77e1db5b217cde1b0f40909ee3916959519173f7
[preflight] Running pre-flight checks
[WARNING Service-Kubelet]: kubelet service is not enabled, please run 'systemctl enable kubelet.service'
[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.
将kubelet设为开机自启动
systemctl enable kubelet.service
回到主节点，查看从节点是否加入成功
需要等几分钟，直到所有Pod创建完成，如下:
watch kubectl get pods -A
NAMESPACE NAME READY STATUS RESTARTS AGE
calico-apiserver calico-apiserver-7f67554766-dfzc9 1/1 Running 0 22m
calico-apiserver calico-apiserver-7f67554766-xsdlk 1/1 Running 0 22m
calico-system calico-kube-controllers-6b7df74554-qxqgf 1/1 Running 0 22m
calico-system calico-node-7lhhg 1/1 Running 0 10m
calico-system calico-node-ksrfp 1/1 Running 0 22m
calico-system calico-node-lnt8q 1/1 Running 0 10m
calico-system calico-typha-6855cf6f56-dzfd4 1/1 Running 0 22m
calico-system calico-typha-6855cf6f56-z77jt 1/1 Running 0 10m
calico-system csi-node-driver-cn6h5 2/2 Running 0 10m
calico-system csi-node-driver-pqrw8 2/2 Running 0 10m
calico-system csi-node-driver-rhd5m 2/2 Running 0 22m
kube-system coredns-5dd5756b68-84wqr 1/1 Running 0 5h32m
kube-system coredns-5dd5756b68-hc9xm 1/1 Running 0 5h32m
kube-system etcd-k8s-master 1/1 Running 0 5h32m
kube-system kube-apiserver-k8s-master 1/1 Running 0 5h32m
kube-system kube-controller-manager-k8s-master 1/1 Running 0 5h32m
kube-system kube-proxy-2hmd5 1/1 Running 0 10m
kube-system kube-proxy-4h2cz 1/1 Running 0 10m
kube-system kube-proxy-6qptd 1/1 Running 0 5h32m
kube-system kube-scheduler-k8s-master 1/1 Running 0 5h32m
tigera-operator tigera-operator-c7ccbd65-rddsw 1/1 Running 0 5h25m
可以查到两个从节点已经Ready
# kubectl get nodes
NAME STATUS ROLES AGE VERSION
k8s-master Ready control-plane 5h33m v1.28.2
k8s-node1 Ready <none> 11m v1.28.2
k8s-node2 Ready <none> 11m v1.28.2
# calicoctl node status
calicoctl node status
Calico process is running.
IPv4 BGP status
+---------------+-------------------+-------+----------+-------------+
| PEER ADDRESS | PEER TYPE | STATE | SINCE | INFO |
+---------------+-------------------+-------+----------+-------------+
| 10.206.216.98 | node-to-node mesh | up | 08:48:32 | Established |
| 10.206.216.99 | node-to-node mesh | up | 08:49:43 | Established |
+---------------+-------------------+-------+----------+-------------+
IPv6 BGP status
No IPv6 peers found.
# calicoctl get nodes
NAME
k8s-master
k8s-node1
k8s-node2
5. 测试集群，在集群上部署Nginx
创建Nginx deployment, 设置副本数为3
apiVersion: apps/v1
kind: Deployment
metadata:
name: nginx-deployment
spec:
selector:
matchLabels:
app: nginx
replicas: 3 # 副本数设置为3，假设集群中有三个节点，每个节点上会尝试运行一个Nginx实例（但k8s会根据资源情况和调度策略来实际分配）
template:
metadata:
labels:
app: nginx
spec:
containers:
- name: nginx
image: nginx:latest
ports:
- containerPort: 80
使用kubectl apply -f nginx-deployment.yaml命令部署Nginx
# kubectl get pods -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
nginx-deployment-7c79c4bf97-2bk2q 1/1 Running 0 22m 198.18.169.130 k8s-node2 <none> <none>
nginx-deployment-7c79c4bf97-5pdr5 1/1 Running 0 22m 198.18.235.199 k8s-master <none> <none>
nginx-deployment-7c79c4bf97-w4s8h 1/1 Running 0 22m 198.18.36.66 k8s-node1 <none> <none>
可以看到，每个节点都成功部署了一个Nginx
删除所有节点的Nginx Pod
[root@k8s-master ~]# kubectl delete deploy nginx-deployment
deployment.apps "nginx-deployment" deleted
6. 从节点退出集群
在主节点下删除节点
kubectl delete node k8s-node1
kubectl delete node k8s-node2
从节点退出后，如果想重新加入，在从节点上执行如下命令
systemctl stop kubelet
rm -rf /etc/kubernetes/*
kubeadm join ... # 从节点上执行，重新加入集群
参考
【1】 https://medium.com/@redswitches/install-kubernetes-on-rocky-linux-9-b01909d6ba72
【2】 https://juejin.cn/post/7286669548740591673
【3】 https://cloud.tencent.com/developer/article/2255721
原文地址：https://blog.csdn.net/pcj_888/article/details/144240636
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