kubeadm 方式安装k8s集群

环境准备 #

准备三台Linux机器（本文以Ubuntu20.04LTS系统为例），三台机器之间能相互通信，我这边使用vps，不方便泄露IP见谅。

以下是本文使用的三台Ubuntu 20.04LTS：

hostname	system	memory
k8s-master	Ubuntu 20.04 LTS	8GB
k8s-worker1	Ubuntu 20.04 LTS	8GB
k8s-worker2	Ubuntu 20.04 LTS	8GB

安装containerd, kubeadm, kubelet, kubectl##

把下面的shell脚本保存成一个文件，比如叫master.sh，放到三台机器里。

然后分别在三台机器上执行sudo sh master.sh 运行脚本。

如果要修改Kubernetes版本，请修改下面脚本的最后一行，当前我们使用的版本是 1.28.0, 可以通过命令 apt list -a kubeadm 查看可用版本

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#!/bin/bash
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echo "[TASK 1] Disable and turn off SWAP"
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sed -i '/swap/d' /etc/fstab
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swapoff -a
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echo "[TASK 2] Stop and Disable firewall"
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systemctl disable --now ufw >/dev/null 2>&1
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echo "[TASK 3] Enable and Load Kernel modules"
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cat >>/etc/modules-load.d/containerd.conf<<EOF
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overlay
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br_netfilter
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EOF
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modprobe overlay
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modprobe br_netfilter
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echo "[TASK 4] Add Kernel settings"
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cat >>/etc/sysctl.d/kubernetes.conf<<EOF
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net.bridge.bridge-nf-call-ip6tables = 1
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net.bridge.bridge-nf-call-iptables  = 1
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net.ipv4.ip_forward                 = 1
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EOF
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sysctl --system >/dev/null 2>&1
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echo "[TASK 5] Install containerd runtime"
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mkdir -p /etc/apt/keyrings
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curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo gpg --dearmor -o /etc/apt/keyrings/docker.gpg
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echo   "deb [arch=$(dpkg --print-architecture) signed-by=/etc/apt/keyrings/docker.gpg] https://download.docker.com/linux/ubuntu \
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  $(lsb_release -cs) stable" | sudo tee /etc/apt/sources.list.d/docker.list > /dev/null
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apt -qq update >/dev/null 2>&1
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apt install -qq -y containerd.io >/dev/null 2>&1
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containerd config default >/etc/containerd/config.toml
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sed -i 's/SystemdCgroup = false/SystemdCgroup = true/' /etc/containerd/config.toml
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systemctl restart containerd
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systemctl enable containerd >/dev/null 2>&1
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echo "[TASK 6] Add apt repo for kubernetes"
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curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | apt-key add - >/dev/null 2>&1
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apt-add-repository "deb http://apt.kubernetes.io/ kubernetes-xenial main" >/dev/null 2>&1
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echo "[TASK 7] Install Kubernetes components (kubeadm, kubelet and kubectl)"
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apt install -qq -y kubeadm=1.28.0-00 kubelet=1.28.0-00 kubectl=1.28.0-00 >/dev/null 2>&1

脚本结束以后，可以检查下kubeadm，kubelet，kubectl的安装情况,如果都能获取到版本号，说明安装成功。

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kubeadm version
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kubelet --version
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kubectl version

初始化master节点#

[admonition title=“Warning” color=“blue”]以下操作都在master节点上进行[/admonition]

可以先拉取集群所需要的images（可做可不做）

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sudo kubeadm config images pull

如果拉取成功，会看到类似下面的输出：

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[config/images] Pulled registry.k8s.io/kube-apiserver:v1.28.2
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[config/images] Pulled registry.k8s.io/kube-controller-manager:v1.28.2
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[config/images] Pulled registry.k8s.io/kube-scheduler:v1.28.2
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[config/images] Pulled registry.k8s.io/kube-proxy:v1.28.2
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[config/images] Pulled registry.k8s.io/pause:3.9
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[config/images] Pulled registry.k8s.io/etcd:3.5.6-0
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[config/images] Pulled registry.k8s.io/coredns/coredns:v1.9.3

初始化Kubeadm

--apiserver-advertise-address 这个地址是本地用于和其他节点通信的IP地址，即Master 节点IP
--pod-network-cidr pod network 地址空间

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vagrant@k8s-master:~$ sudo kubeadm init --apiserver-advertise-address=192.168.56.10  --pod-network-cidr=10.244.0.0/16

最后一段的输出要保存好, 这一段指出后续需要做什么配置。

准备 .kube
部署pod network方案
添加worker节点

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Your Kubernetes control-plane has initialized successfully!
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To start using your cluster, you need to run the following as a regular user:
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  mkdir -p $HOME/.kube
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  sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
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  sudo chown $(id -u):$(id -g) $HOME/.kube/config
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Alternatively, if you are the root user, you can run:
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  export KUBECONFIG=/etc/kubernetes/admin.conf
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You should now deploy a pod network to the cluster.
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Run "kubectl apply -f [podnetwork].yaml" with one of the options listed at:
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  https://kubernetes.io/docs/concepts/cluster-administration/addons/
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Then you can join any number of worker nodes by running the following on each as root:
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kubeadm join ip:6443 --token 75tjpr.mekbas8r3yvimqen \
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        --discovery-token-ca-cert-hash sha256:3366cd93860eaac418ce9b35dda601c88676fe6ba99388672aba4e76cc7369e4

配置 .kube#

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

检查状态#

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$ kubectl get nodes
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$ kubectl get pods -A

shell 自动补全(Bash)#

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source <(kubectl completion bash)
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echo "source <(kubectl completion bash)" >> ~/.bashrc

部署pod network方案#

去https://kubernetes.io/docs/concepts/cluster-administration/addons/ 选择一个network方案，根据提供的具体链接去部署。

这里我们选择overlay的方案，名字叫 flannel 部署方法如下：

下载文件 https://raw.githubusercontent.com/flannel-io/flannel/master/Documentation/kube-flannel.yml ，并进行如下修改：

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curl -LO https://raw.githubusercontent.com/flannel-io/flannel/master/Documentation/kube-flannel.yml

确保network是我们配置的 –pod-network-cidr 10.244.0.0/16

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net-conf.json: |
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  {
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    "Network": "10.244.0.0/16",
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    "Backend": {
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      "Type": "vxlan"
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    }
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  }

在 kube-flannel的容器args里，确保有iface=网卡名是我们的–apiserver-advertise-address=ip 接口名

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ip a

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- name: kube-flannel
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 #image: flannelcni/flannel:v0.18.0 for ppc64le and mips64le (dockerhub limitations may apply)
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  image: rancher/mirrored-flannelcni-flannel:v0.18.0
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  command:
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  - /opt/bin/flanneld
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  args:
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  - --ip-masq
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  - --kube-subnet-mgr
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  - --iface=网卡名

举例：

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vagrant@k8s-master:~$ ip a
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1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
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    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
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    inet 127.0.0.1/8 scope host lo
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      valid_lft forever preferred_lft forever
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    inet6 ::1/128 scope host
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      valid_lft forever preferred_lft forever
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2: enp0s3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
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    link/ether 02:9a:67:51:1e:b6 brd ff:ff:ff:ff:ff:ff
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    inet 10.0.2.15/24 brd 10.0.2.255 scope global dynamic enp0s3
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      valid_lft 85351sec preferred_lft 85351sec
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    inet6 fe80::9a:67ff:fe51:1eb6/64 scope link
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      valid_lft forever preferred_lft forever
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3: enp0s8: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
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    link/ether 08:00:27:59:c5:26 brd ff:ff:ff:ff:ff:ff
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    inet 192.168.56.10/24 brd 192.168.56.255 scope global enp0s8
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      valid_lft forever preferred_lft forever
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    inet6 fe80::a00:27ff:fe59:c526/64 scope link
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      valid_lft forever preferred_lft forever

检查结果，如果显示下面的结果，pod都是running的状态，说明我们的network方案部署成功（特别是coredns和flannel)。

添加worker节点 #

添加worker节点非常简单，直接在worker节点上运行join即可，注意–token

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sudo kubeadm join 192.168.56.10:6443 --token 0pdoeh.wrqchegv3xm3k1ow \
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  --discovery-token-ca-cert-hash sha256:f4e693bde148f5c0ff03b66fb24c51f948e295775763e8c5c4e60d24ff57fe82

最后在master节点查看node和pod结果。(比如我们有两个worker节点)

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kubectl get nodes