Kubernetes 是一个可移植的、可扩展的开源平台，用于管理容器化的工作负载和服务，可促进声明式配置和自动化。Kubernetes 拥有一个庞大且快速增长的生态系统。Kubernetes 的服务、支持和工具广泛可用。

Kubernetes是一个全新的基于容器技术的分布式领先方案。简称：K8S。它是Google开源的容器集群管理系统，它的设计灵感来自于Google内部的一个叫作Borg的容器管理系统。继承了Google十余年的容器集群使用经验。它为容器化的应用提供了部署运行、资源调度、服务发现和动态伸缩等一些列完整的功能，极大地提高了大规模容器集群管理的便捷性。

kubernetes是一个完备的分布式系统支撑平台。具有完备的集群管理能力，多扩多层次的安全防护和准入机制、多租户应用支撑能力、透明的服务注册和发现机制、內建智能负载均衡器、强大的故障发现和自我修复能力、服务滚动升级和在线扩容能力、可扩展的资源自动调度机制以及多粒度的资源配额管理能力。

在集群管理方面，Kubernetes将集群中的机器划分为一个Master节点和一群工作节点Node，其中，在Master节点运行着集群管理相关的一组进程kube-apiserver、kube-controller-manager和kube-scheduler，这些进程实现了整个集群的资源管理、Pod调度、弹性伸缩、安全控制、系统监控和纠错等管理能力，并且都是全自动完成的。Node作为集群中的工作节点，运行真正的应用程序，在Node上Kubernetes管理的最小运行单元是Pod。Node上运行着Kubernetes的kubelet、kube-proxy服务进程，这些服务进程负责Pod的创建、启动、监控、重启、销毁以及实现软件模式的负载均衡器。

在Kubernetes集群中，它解决了传统IT系统中服务扩容和升级的两大难题。如果今天的软件并不是特别复杂并且需要承载的峰值流量不是特别多，那么后端项目的部署其实也只需要在虚拟机上安装一些简单的依赖，将需要部署的项目编译后运行就可以了。但是随着软件变得越来越复杂，一个完整的后端服务不再是单体服务，而是由多个职责和功能不同的服务组成，服务之间复杂的拓扑关系以及单机已经无法满足的性能需求使得软件的部署和运维工作变得非常复杂，这也就使得部署和运维大型集群变成了非常迫切的需求。

Kubernetes 的出现不仅主宰了容器编排的市场，更改变了过去的运维方式，不仅将开发与运维之间边界变得更加模糊，而且让 DevOps 这一角色变得更加清晰，每一个软件工程师都可以通过 Kubernetes 来定义服务之间的拓扑关系、线上的节点个数、资源使用量并且能够快速实现水平扩容、蓝绿部署等在过去复杂的运维操作。

2、k8s组件

在K8S中，分为两种资源。
1、集群级资源
2、命名空间级资源

Master   
    kube-apiserver    
    kube-controller-manager    
    kube-scheduler  
    kubelet   
    kube-proxy    
    CoreDNS   
    flannel

Worker

    flannel

    kubelet

    kube-proxy

3、kubeadm安装Master

1、修改主机名
[root@localhost ~]# hostnamectl set-hostname k8s-master-01

2、解析Hostname
[root@localhost ~]# vi /etc/hosts
192.168.11.101 k8s-master-01

3、关闭Selinux和防火墙
[root@localhost ~]# setenforce 0
[root@localhost ~]# vi /etc/selinux/config
SELINUX=disabled
[root@localhost ~]# systemctl disable --now firewalld

4、升级系统内核
yum localinstall -y kernel-lt*
grub2-set-default  0 && grub2-mkconfig -o /etc/grub2.cfg
grubby --default-kernel
reboot

5、关闭swap分区
echo 'KUBELET_EXTRA_ARGS="--fail-swap-on=false"' > /etc/sysconfig/kubelet

6、安装IPVS
# 安装IPVS
yum install -y conntrack-tools ipvsadm ipset conntrack libseccomp
# 加载IPVS模块
cat > /etc/sysconfig/modules/ipvs.modules <<EOF
#!/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
EOF

chmod 755 /etc/sysconfig/modules/ipvs.modules && bash /etc/sysconfig/modules/ipvs.modules && lsmod | grep ip_vs


7、设置内核参数
cat > /etc/sysctl.d/k8s.conf << EOF
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
EOF

# 立即生效
sysctl --system


8、安装基础软件
yum install wget expect vim net-tools ntp bash-completion ipvsadm ipset jq iptables conntrack sysstat libseccomp -y

9、安装docker
scp 。。。
yum install -y yum-utils device-mapper-persistent-data lvm2
yum-config-manager --add-repo https://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo

yum install docker-ce-19.03.9 -y
sudo mkdir -p /etc/docker
sudo tee /etc/docker/daemon.json <<-'EOF'
{
  "registry-mirrors": ["https://8mh75mhz.mirror.aliyuncs.com"]
}
EOF
sudo systemctl daemon-reload ; systemctl restart docker;systemctl enable --now docker.service

10、安装k8s
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

yum install -y kubelet-1.21.3 kubeadm-1.21.3 kubectl-1.21.3

systemctl enable kubelet && systemctl start kubelet

11、初始化k8s
kubeadm init \
--image-repository=registry.cn-hangzhou.aliyuncs.com/k8sos \
--kubernetes-version=v1.21.3 \
--service-cidr=10.96.0.0/12 \
--pod-network-cidr=10.244.0.0/16

--image-repository : 下载镜像的仓库
--kubernetes-version ： 指定安装k8s的版本
--service-cidr ： 指定k8s service的网段
--pod-network-cidr ：指定Pod的网段


按照提示
复制（见下图）


12、安装网络插件
[root@localhost ~]# kubectl apply -f kube-flannel.yaml 

kubectl get pods -n kube-system -w  #查看是否安装完成

13、测试
kubectl run -it --rm test --image=busybox:1.28.3 (这里只有master节点，所以不会成功)

 

 github.com--搜索 flannel--Documentation--kube-flannel.yml——复制粘贴到kube-flannel.yaml    即以下内容

---
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-plugin
        image: rancher/mirrored-flannelcni-flannel-cni-plugin:v1.0.0
        command:
        - cp
        args:
        - -f
        - /flannel
        - /opt/cni/bin/flannel
        volumeMounts:
        - name: cni-plugin
          mountPath: /opt/cni/bin
      - name: install-cni
        image: quay.io/coreos/flannel:v0.15.1
        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: quay.io/coreos/flannel:v0.15.1
        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-plugin
        hostPath:
          path: /opt/cni/bin
      - name: cni
        hostPath:
          path: /etc/cni/net.d
      - name: flannel-cfg
        configMap:
          name: kube-flannel-cfg

4.kubeadm安装worker节点 192.168.15.104

1、修改主机名
[root@localhost ~]# hostnamectl set-hostname k8s-node-01

2、解析Hostname（master 和worker节点都要解析）
[root@localhost ~]# vi /etc/hosts
192.168.11.101 k8s-master-01
192.168.11.104 k8s-node-01

3、关闭Selinux和防火墙
[root@localhost ~]# setenforce 0
[root@localhost ~]# vi /etc/selinux/config
SELINUX=disabled
[root@localhost ~]# systemctl disable --now firewalld

4、升级系统内核
yum localinstall -y kernel-lt*
grub2-set-default  0 && grub2-mkconfig -o /etc/grub2.cfg
grubby --default-kernel
reboot

5、关闭swap分区
echo 'KUBELET_EXTRA_ARGS="--fail-swap-on=false"' > /etc/sysconfig/kubelet

6、安装IPVS
# 安装IPVS
yum install -y conntrack-tools ipvsadm ipset conntrack libseccomp
# 加载IPVS模块
cat > /etc/sysconfig/modules/ipvs.modules <<EOF
#!/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
EOF

chmod 755 /etc/sysconfig/modules/ipvs.modules && bash /etc/sysconfig/modules/ipvs.modules && lsmod | grep ip_vs


7、设置内核参数
cat > /etc/sysctl.d/k8s.conf << EOF
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
EOF

# 立即生效
sysctl --system


8、安装基础软件
yum install wget expect vim net-tools ntp bash-completion ipvsadm ipset jq iptables conntrack sysstat libseccomp -y

9、安装docker

[root@localhost ~]# scp kernel-lt-* root@192.168.15.101:/root

yum install -y yum-utils device-mapper-persistent-data lvm2
yum-config-manager --add-repo https://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo

yum install docker-ce-19.03.9 -y
sudo mkdir -p /etc/docker
sudo tee /etc/docker/daemon.json <<-'EOF'
{
  "registry-mirrors": ["https://8mh75mhz.mirror.aliyuncs.com"]
}
EOF
sudo systemctl daemon-reload ; systemctl restart docker;systemctl enable --now docker.service

10、安装k8s
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

yum install -y kubelet-1.21.3 kubeadm-1.21.3 kubectl-1.21.3

systemctl enable kubelet && systemctl start kubelet

11、加入Master  （注意每台机器的不一样哦，按自己机器上的）
[root@k8s-node-01 ~]# kubeadm join 192.168.11.101:6443 --token foy413.nu3umjkcq3cjhvsz \
> --discovery-token-ca-cert-hash sha256:be1fa9173275c5bdff1430ab53279d9f5a256f1a53a486dda1a1986db9203fad 

在master上 查看是否是ready状态
   [root@k8s-master-01 ~]# kubectl get nodes

12、测试集群网络
[root@k8s-master-01 ~]# kubectl run test -it --rm --image=busybox:1.28.3
If you don't see a command prompt, try pressing enter.
/ # nslookup kubernetes
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
出现上面的表示安装成功

附：报错swap解决方案

关闭swap

第一步关闭swap分区:(fdisk 查看磁盘分区)
swapoff /mnt/swap
1
第二步修改配置文件 - /etc/fstab
删除 /mnt/swap swap swap defaults 0 0 这一行或者注释掉这一行

第三步确认swap已经关闭
free -m
1
若都显示 0 则表示关闭成功
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原文链接：https://blog.csdn.net/dejunyang/article/details/97972399