kubernetes===》kubeadm安装

一、kubeadm安装

服务器配置至少是2G2核的。如果不是则可以在集群初始化后面增加 --ignore-preflight-errors=NumCPU

1.准备环境

1）部署软件、系统要求

软件	版本
Centos	CentOS Linux release 7.5及以上
Docker	19.03.12
Kubernetes	V1.19.1
Flannel	V0.13.0
Kernel-lm	kernel-lt-4.4.245-1.el7.elrepo.x86_64.rpm
Kernel-lm-deve	kernel-lt-devel-4.4.245-1.el7.elrepo.x86_64.rpm

2）节点规划

IP建议采用192网段，避免与kubernetes内网冲突

二、部署k8s

1、系统优化（所有节点都做）

1）关闭swap分区

#1.一旦触发 swap，会导致系统性能急剧下降，所以一般情况下，K8S 要求关闭 swap
vim /etc/fstab
用#注释掉UUID swap分区那一行

swapoff -a 
echo 'KUBELET_EXTRA_ARGS="--fail-swap-on=false"' > /etc/sysconfig/kubelet

2）关闭selinux、firewalld

sed -i 's#enforcing#disabled#g' /etc/selinux/config
setenforce 0  #临时关闭selinux
systemctl disable firewalld  #永久关闭selinux

3)修改主机名并且做域名解析

#1.修改主机名
hostnamectl set-hostname k8s-master1
hostnamectl set-hostname k8s-node1
hostnamectl set-hostname k8s-node2

#2.修改hosts文件 (主节点)
vim /etc/hosts
192.168.12.11  k8s-master1 m1
192.168.12.12  k8s-node1   n1
192.168.12.13  k8s-node2   n2

4）配置免密登录、分发公钥（主节点）

ssh-keygen -t rsa
for i in m1 n1 n2;do ssh-copy-id -i ~/.ssh/id_rsa.pub root@$i;done

5）同步集群时间

在集群中，时间是一个很重要的概念，一旦集群当中某台机器视觉按跟集群时间不一致，可能会导致集群面临很多问题。所以，在部署集群之前，需要同步集群当中的所有机器时间
yum install ntpdate -y
ln -sf /usr/share/zoneinfo/Asia/Shanghai /etc/localtime
echo 'Asia/Shanghai' > /etc/timezone
ntpdate time2.aliyun.com
#写入定时任务
*/1 * * * * ntpdate time2.aliyun.com > /dev/null 2>&1

6）配置镜像源

#1.默认情况下，centos使用的是官方yum源，所以一般情况下在国内使用时非常慢的，所以我们可以替换成国内的一些比较成熟的yum源，例如：清华大学镜像源，网易云镜像源等等。
curl  -o /etc/yum.repos.d/CentOS-Base.repo https://repo.huaweicloud.com/repository/conf/CentOS-7-reg.repo

#2.刷新缓存
 yum clean all
 
 yum makecache

7）更新系统

yum update -y --exclud=kernel*

8）安装基础常用软件

yum install wget expect vim net-tools ntp bash-completion ipvsadm ipset jq iptables conntrack sysstat libseccomp -y

9）更新系统内核（docker对系统内核要求比较高，最好用4.4+）

#如果是centos8则不需要升级内核
wget https://elrepo.org/linux/kernel/el7/x86_64/RPMS/kernel-lt-5.4.107-1.el7.elrepo.x86_64.rpm

wget  https://elrepo.org/linux/kernel/el7/x86_64/RPMS/kernel-lt-devel-5.4.107-1.el7.elrepo.x86_64.rpm

10）安装系统内容

yum localinstall -y kernel-lt*

grub2-set-default  0 && grub2-mkconfig -o /etc/grub2.cfg  #调到默认启动

grubby --default-kernel  #查看当前默认启动的内核

reboot  #重启

11）安装IPVS

#IPVS是系统内核中的一个模块，其网络转发性能很高。一般情况下我们首选ipvs
yum install -y conntrack-tools ipvsadm ipset conntrack libseccomp

vim /etc/sysconfig/modules/ipvs.modules  #加载IPVS模块
#!/bin/bash
    ipvs_modules="ip_vs ip_vs_lc ip_vs_wlc ip_vs_rr ip_vs_wrr ip_vs_lblc ip_vs_lblcr ip_vs_dh ip_vs_sh ip_vs_fo ip_vs_nq ip_vs_sed ip_vs_ftp nf_conntrack"
    for kernel_module in \${ipvs_modules}; do
      /sbin/modinfo -F filename \${kernel_module} > /dev/null 2>&1
      if [ $? -eq 0 ]; then
        /sbin/modprobe \${kernel_module}
      fi
    done

chmod 755 /etc/sysconfig/modules/ipvs.modules && bash   #给文件修改权限

/etc/sysconfig/modules/ipvs.modules && lsmod | grep ip_vs

12）修改内核启动参数

#内核参数优化的主要目的是使其更合适kubernetes的正常运行
vim /etc/sysctl.d/k8s.conf
net.ipv4.ip_forward = 1
net.bridge.bridge-nf-call-iptables = 1
net.bridge.bridge-nf-call-ip6tables = 1
fs.may_detach_mounts = 1
vm.overcommit_memory=1
vm.panic_on_oom=0
fs.inotify.max_user_watches=89100
fs.file-max=52706963
fs.nr_open=52706963
net.ipv4.tcp_keepalive_time = 600
net.ipv4.tcp.keepaliv.probes = 3
net.ipv4.tcp_keepalive_intvl = 15
net.ipv4.tcp.max_tw_buckets = 36000
net.ipv4.tcp_tw_reuse = 1
net.ipv4.tcp.max_orphans = 327680
net.ipv4.tcp_orphan_retries = 3
net.ipv4.tcp_syncookies = 1
net.ipv4.tcp_max_syn_backlog = 16384
net.ipv4.ip_conntrack_max = 65536
net.ipv4.tcp_max_syn_backlog = 16384
net.ipv4.top_timestamps = 0
net.core.somaxconn = 16384

sysctl --system  #立即生效

2.安装docker（所有节点）

docker主要是作为k8s管理得常用的容器工具之一

#1.卸载之前安装过的docker
sudo yum remove docker docker-common docker-selinux docker-engine

#2.安装docker需要的依赖包
sudo yum install -y yum-utils device-mapper-persistent-data lvm2

#3.安装docker的yum源
wget -O /etc/yum.repos.d/docker-ce.repo https://repo.huaweicloud.com/docker-ce/linux/centos/docker-ce.repo

#4.安装docker
yum install docker-ce -y

#5.设置开机自启
systemctl enable --now docker.service

3.安装kubele(所有节点)

#1.安装kebenetes  yum源
vim /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

#2.安装kubelet
yum install -y kubelet kubeadm kubectl 
systemctl enable --now kubelet

4.初始化master节点（只在master节点执行）

 kubeadm init \
 --image-repository=registry.cn-hangzhou.aliyuncs.com/k8sos \
--kubernetes-version=v1.20.2 \
--service-cidr=10.96.0.0/12 \
--pod-network-cidr=10.244.0.0/16

5.初始化后续（只在master节点执行）

#1.建立用户集群权限
mkdir -p $HOME/.kube
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
sudo chown $(id -u):$(id -g) $HOME/.kube/config
 #如果是root用户，则可以使用：export KUBECONFIG=/etc/kubernetes/admin.conf

#2.安装集群网络插件（flannel.yaml）
vi /root/flannel.yaml
---
apiVersion: policy/v1beta1
kind: PodSecurityPolicy
metadata:
  name: psp.flannel.unprivileged
  annotations:
    seccomp.security.alpha.kubernetes.io/allowedProfileNames: docker/default
    seccomp.security.alpha.kubernetes.io/defaultProfileName: docker/default
    apparmor.security.beta.kubernetes.io/allowedProfileNames: runtime/default
    apparmor.security.beta.kubernetes.io/defaultProfileName: runtime/default
spec:
  privileged: false
  volumes:
  - configMap
  - secret
  - emptyDir
  - hostPath
  allowedHostPaths:
  - pathPrefix: "/etc/cni/net.d"
  - pathPrefix: "/etc/kube-flannel"
  - pathPrefix: "/run/flannel"
  readOnlyRootFilesystem: false
  # Users and groups
  runAsUser:
    rule: RunAsAny
  supplementalGroups:
    rule: RunAsAny
  fsGroup:
    rule: RunAsAny
  # Privilege Escalation
  allowPrivilegeEscalation: false
  defaultAllowPrivilegeEscalation: false
  # Capabilities
  allowedCapabilities: ['NET_ADMIN', 'NET_RAW']
  defaultAddCapabilities: []
  requiredDropCapabilities: []
  # Host namespaces
  hostPID: false
  hostIPC: false
  hostNetwork: true
  hostPorts:
  - min: 0
    max: 65535
  # SELinux
  seLinux:
    # SELinux is unused in CaaSP
    rule: 'RunAsAny'
---
kind: ClusterRole
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: flannel
rules:
- apiGroups: ['extensions']
  resources: ['podsecuritypolicies']
  verbs: ['use']
  resourceNames: ['psp.flannel.unprivileged']
- apiGroups:
  - ""
  resources:
  - pods
  verbs:
  - get
- apiGroups:
  - ""
  resources:
  - nodes
  verbs:
  - list
  - watch
- apiGroups:
  - ""
  resources:
  - nodes/status
  verbs:
  - patch
---
kind: ClusterRoleBinding
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: flannel
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: flannel
subjects:
- kind: ServiceAccount
  name: flannel
  namespace: kube-system
---
apiVersion: v1
kind: ServiceAccount
metadata:
  name: flannel
  namespace: kube-system
---
kind: ConfigMap
apiVersion: v1
metadata:
  name: kube-flannel-cfg
  namespace: kube-system
  labels:
    tier: node
    app: flannel
data:
  cni-conf.json: |
    {
    
    
      "name": "cbr0",
      "cniVersion": "0.3.1",
      "plugins": [
        {
    
    
          "type": "flannel",
          "delegate": {
    
    
            "hairpinMode": true,
            "isDefaultGateway": true
          }
        },
        {
    
    
          "type": "portmap",
          "capabilities": {
    
    
            "portMappings": true
          }
        }
      ]
    }
  net-conf.json: |
    {
    
    
      "Network": "10.244.0.0/16",
      "Backend": {
    
    
        "Type": "vxlan"
      }
    }
---
apiVersion: apps/v1
kind: DaemonSet
metadata:
  name: kube-flannel-ds
  namespace: kube-system
  labels:
    tier: node
    app: flannel
spec:
  selector:
    matchLabels:
      app: flannel
  template:
    metadata:
      labels:
        tier: node
        app: flannel
    spec:
      affinity:
        nodeAffinity:
          requiredDuringSchedulingIgnoredDuringExecution:
            nodeSelectorTerms:
            - matchExpressions:
              - key: kubernetes.io/os
                operator: In
                values:
                - linux
      hostNetwork: true
      priorityClassName: system-node-critical
      tolerations:
      - operator: Exists
        effect: NoSchedule
      serviceAccountName: flannel
      initContainers:
      - name: install-cni
        image: registry.cn-hangzhou.aliyuncs.com/alvinos/flanned:v0.13.1-rc1
        command:
        - cp
        args:
        - -f
        - /etc/kube-flannel/cni-conf.json
        - /etc/cni/net.d/10-flannel.conflist
        volumeMounts:
        - name: cni
          mountPath: /etc/cni/net.d
        - name: flannel-cfg
          mountPath: /etc/kube-flannel/
      containers:
      - name: kube-flannel
        image: registry.cn-hangzhou.aliyuncs.com/alvinos/flanned:v0.13.1-rc1
        command:
        - /opt/bin/flanneld
        args:
        - --ip-masq
        - --kube-subnet-mgr
        resources:
          requests:
            cpu: "100m"
            memory: "50Mi"
          limits:
            cpu: "100m"
            memory: "50Mi"
        securityContext:
          privileged: false
          capabilities:
            add: ["NET_ADMIN", "NET_RAW"]
        env:
        - name: POD_NAME
          valueFrom:
            fieldRef:
              fieldPath: metadata.name
        - name: POD_NAMESPACE
          valueFrom:
            fieldRef:
              fieldPath: metadata.namespace
        volumeMounts:
        - name: run
          mountPath: /run/flannel
        - name: flannel-cfg
          mountPath: /etc/kube-flannel/
      volumes:
      - name: run
        hostPath:
          path: /run/flannel
      - name: cni
        hostPath:
          path: /etc/cni/net.d
      - name: flannel-cfg
        configMap:
          name: kube-flannel-cfg

kubectl apply -f flannel.yaml

#3.将node节点加入集群
[root@gdx1 ~]# kubeadm token create    --print-join-command 
kubeadm join 192.168.15.31:6443 --token s6svmh.lw88lchyl6m24tts     --discovery-token-ca-cert-hash sha256:4d7e3e37e73176a97322e26fe501d2c27830a7bf3550df56f3a55b68395b507b 
注：将上方生成的内容（token）复制到node的两台节点上执行

6.检查集群状态（主节点）

#1.第一种方式
kubectl get nodes
NAME       STATUS   ROLES                  AGE   VERSION
k8s-m-01   Ready    control-plane,master   13m   v1.20.5
k8s-n-01   Ready    <none>                 35s   v1.20.5
k8s-n-02   Ready    <none>                 39s   v1.20.5
注：都出现ready的状态就证明成功

#2.第二种方式
kubectl get pods -n kube-system
NAME                               READY   STATUS    RESTARTS   AGE
coredns-f68b4c98f-5t7wm            1/1     Running   0          5m54s
coredns-f68b4c98f-5xqjs            1/1     Running   0          5m54s
etcd-k8s-m-01                      1/1     Running   0          6m3s
kube-apiserver-k8s-m-01            1/1     Running   0          6m3s
kube-controller-manager-k8s-m-01   1/1     Running   0          6m3s
kube-flannel-ds-7bcwl              1/1     Running   0          104s
kube-proxy-ntpjx                   1/1     Running   0          5m54s
kube-scheduler-k8s-m-01            1/1     Running   0          6m3s
注：看到所有状态都是1/1就证明成功

#3.第三种方式：直接验证集群DNS
kubectl run test -it --rm --image=busybox:1.28.3
If you don't see a command prompt, try pressing enter.
/ # nslookup kubernetes  #进入容器输入这行内容（有内容反馈就证明成功）
Server:    10.96.0.10
Address 1: 10.96.0.10 kube-dns.kube-system.svc.cluster.local

Name:      kubernetes
Address 1: 10.96.0.1 kubernetes.default.svc.cluster.local