简单理解：
docker默认是单机使用的，不可以跨主机，也没有高可用，所以生产环境一般不会单独使用docker跑应用，k8s主要是作为docker的一个调度器来使用，可以使容器实现跨节点通信，当一台运行容器的节点故障后，容器会自动迁移到其它可用节点上继续运行服务，目前比较常用的是k8s
k8s架构：k8s主要由master节点和node节点构成，而且常用操作都在master上操作，作为控制节点角色，node节点提供计算功能
master：
kubectl:k8s的所有操作都是通过kubectl指令操作的
REST API：k8s对外部服务提供的接口服务，例如图形化界面或者kubectl都会通过REST API接口下发指令来控制k8s
scheduler：调度器，例如创建pod，scheduler可以控制将pod分配到哪个pod节点
controller-manager：检测pod或者node的健康状态，并维持pod的正常运行，如果pod故障，controller-manger会自动修复，例如在启动一个pod副本
kubelet：代理软件，例如在master上对node节点下发的指令，都需要通过kubelet组建来告知各个组件
etcd：数据库，所有配置数据都存放在etcd数据库中
kubeproxy:在所有节点都需要运行kubeproxy，后期通过创建svc来将pod映射到外网，当外部通过svc-ip访问pod的时候就需要通过kubeporxy进行路由转发到pod
node：
pod：k8s环境运行的最小单位，一个pod中可以包含一个或多个容器
安装方式：
kubeadmin（生产）
yum
源码安装（学习，深刻理解）
===================================================================================
节点规划
开始安装：
初始化各个节点的配置：
安装常用工具
yum -y install wget telnet net-tools lrzsz vim zip unzip
修改主机名
将master节点主机名修改为k8s-master01 node节点为k8s-node01 以这种命名规则命名即可
关闭防火墙
[root@k8s-node01 ~]# systemctl stop firewalld && systemctl disable firewalld
永久关闭selinux
[root@k8s-node01 ~]# sed -i 's/SELINUX=enforcing/SELINUX=disabled/' /etc/selinux/config;cat /etc/selinux/config
临时关闭selinux
[root@k8s-node01 ~]# setenforce 0
配置hosts
[root@k8s-node01 ~]# cat >> /etc/hosts <<EOF 10.1.1.100 k8s-master01 10.1.1.110 k8s-node01 10.1.1.120 k8s-node02 EOF
临时关闭swap
[root@k8s-node01 ~]# swapoff -a
永久关闭swap
[root@k8s-node01 ~]# vim /etc/fstab
配置yum源(自带的kubernetes版本太低)
rm -rf /etc/yum.repos.d/*
cd /etc/yum.repo/
wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-7.repo
wget -O /etc/yum.repos.d/epel.repo http://mirrors.aliyun.com/repo/epel-7.repo
vim k8s.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
yum clean all && yum makecache
安装docker
[root@k8s-master01 ~]#yum install -y yum-utils device-mapper-persistent-data lvm2
[root@k8s-master01 ~]# yum -y install docker
由于内核不支持 overlay2所以需要升级内核或者禁用overlay2(我们选择禁用，安装完docker可以启动docker测试下是否支持，启动docker不报错的可以忽略这一步)
vim /etc/sysconfig/docker 将 --selinux-enabled=false
启动docker服务
[root@k8s-master01 ~]# systemctl start docker && systemctl enable docker
设置服务器时区
timedatectl set-timezone Asia/Shanghai
设置相关k8s参数
cat > /etc/sysctl.d/k8s.conf << EOF net.bridge.bridge-nf-call-ip6tables = 1 net.bridge.bridge-nf-call-iptables = 1 EOF
[root@k8s-master01 ~]# sysctl -p
[root@k8s-master01 ~]# echo "1" > /proc/sys/net/ipv4/ip_forward
安装k8s相关安装包 这里安装的是1.15.1版本，可以根据自己的需求指定版本，前提是你yum源支持 使用 yum list kube\* 来查看当前yum源支持的最新版本
[root@k8s-master01 ~]#yum -y install kubeadm-1.15.1 kubelet-1.15.1 kubectl-1.15.1
启动服务
[root@k8s-master01 ~]# systemctl restart kubelet && systemctl enable kubelet
====================================以上操作在所有节点执行，如果新加node节点也需要执行上述操作================================================================
开始初始化k8s集群：在master上执行
$ kubeadm init \ --apiserver-advertise-address=10.1.1.100 \ #master组件监听的api地址，这里写masterIP地址即可或者多网卡选择另一个IP地址 --image-repository registry.aliyuncs.com/google_containers \ --kubernetes-version v1.15.1 \ --service-cidr=10.2.0.0/16 \ --pod-network-cidr=10.244.0.0/16
初始化完成后kubelet服务如果没异常的话应该正常启动了
mkdir -p $HOME/.kube sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config sudo chown $(id -u):$(id -g) $HOME/.kube/config
安装flannel网络
vim kube-flannel.yml添加下面内容
--- kind: ClusterRole apiVersion: rbac.authorization.k8s.io/v1beta1 metadata: name: flannel rules: - apiGroups: - "" resources: - pods verbs: - get - apiGroups: - "" resources: - nodes verbs: - list - watch - apiGroups: - "" resources: - nodes/status verbs: - patch --- kind: ClusterRoleBinding apiVersion: rbac.authorization.k8s.io/v1beta1 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", "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: extensions/v1beta1 kind: DaemonSet metadata: name: kube-flannel-ds-amd64 namespace: kube-system labels: tier: node app: flannel spec: template: metadata: labels: tier: node app: flannel spec: hostNetwork: true nodeSelector: beta.kubernetes.io/arch: amd64 tolerations: - operator: Exists effect: NoSchedule serviceAccountName: flannel initContainers: - name: install-cni image: quay.io/coreos/flannel:v0.11.0-amd64 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:v0.11.0-amd64 command: - /opt/bin/flanneld args: - --ip-masq - --kube-subnet-mgr resources: requests: cpu: "100m" memory: "50Mi" limits: cpu: "100m" memory: "50Mi" securityContext: privileged: true env: - name: POD_NAME valueFrom: fieldRef: fieldPath: metadata.name - name: POD_NAMESPACE valueFrom: fieldRef: fieldPath: metadata.namespace volumeMounts: - name: run mountPath: /run - name: flannel-cfg mountPath: /etc/kube-flannel/ volumes: - name: run hostPath: path: /run - name: cni hostPath: path: /etc/cni/net.d - name: flannel-cfg configMap: name: kube-flannel-cfg --- apiVersion: extensions/v1beta1 kind: DaemonSet metadata: name: kube-flannel-ds-arm64 namespace: kube-system labels: tier: node app: flannel spec: template: metadata: labels: tier: node app: flannel spec: hostNetwork: true nodeSelector: beta.kubernetes.io/arch: arm64 tolerations: - operator: Exists effect: NoSchedule serviceAccountName: flannel initContainers: - name: install-cni image: quay.io/coreos/flannel:v0.11.0-arm64 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:v0.11.0-arm64 command: - /opt/bin/flanneld args: - --ip-masq - --kube-subnet-mgr resources: requests: cpu: "100m" memory: "50Mi" limits: cpu: "100m" memory: "50Mi" securityContext: privileged: true env: - name: POD_NAME valueFrom: fieldRef: fieldPath: metadata.name - name: POD_NAMESPACE valueFrom: fieldRef: fieldPath: metadata.namespace volumeMounts: - name: run mountPath: /run - name: flannel-cfg mountPath: /etc/kube-flannel/ volumes: - name: run hostPath: path: /run - name: cni hostPath: path: /etc/cni/net.d - name: flannel-cfg configMap: name: kube-flannel-cfg --- apiVersion: extensions/v1beta1 kind: DaemonSet metadata: name: kube-flannel-ds-arm namespace: kube-system labels: tier: node app: flannel spec: template: metadata: labels: tier: node app: flannel spec: hostNetwork: true nodeSelector: beta.kubernetes.io/arch: arm tolerations: - operator: Exists effect: NoSchedule serviceAccountName: flannel initContainers: - name: install-cni image: quay.io/coreos/flannel:v0.11.0-arm 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:v0.11.0-arm command: - /opt/bin/flanneld args: - --ip-masq - --kube-subnet-mgr resources: requests: cpu: "100m" memory: "50Mi" limits: cpu: "100m" memory: "50Mi" securityContext: privileged: true env: - name: POD_NAME valueFrom: fieldRef: fieldPath: metadata.name - name: POD_NAMESPACE valueFrom: fieldRef: fieldPath: metadata.namespace volumeMounts: - name: run mountPath: /run - name: flannel-cfg mountPath: /etc/kube-flannel/ volumes: - name: run hostPath: path: /run - name: cni hostPath: path: /etc/cni/net.d - name: flannel-cfg configMap: name: kube-flannel-cfg --- apiVersion: extensions/v1beta1 kind: DaemonSet metadata: name: kube-flannel-ds-ppc64le namespace: kube-system labels: tier: node app: flannel spec: template: metadata: labels: tier: node app: flannel spec: hostNetwork: true nodeSelector: beta.kubernetes.io/arch: ppc64le tolerations: - operator: Exists effect: NoSchedule serviceAccountName: flannel initContainers: - name: install-cni image: quay.io/coreos/flannel:v0.11.0-ppc64le 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:v0.11.0-ppc64le command: - /opt/bin/flanneld args: - --ip-masq - --kube-subnet-mgr resources: requests: cpu: "100m" memory: "50Mi" limits: cpu: "100m" memory: "50Mi" securityContext: privileged: true env: - name: POD_NAME valueFrom: fieldRef: fieldPath: metadata.name - name: POD_NAMESPACE valueFrom: fieldRef: fieldPath: metadata.namespace volumeMounts: - name: run mountPath: /run - name: flannel-cfg mountPath: /etc/kube-flannel/ volumes: - name: run hostPath: path: /run - name: cni hostPath: path: /etc/cni/net.d - name: flannel-cfg configMap: name: kube-flannel-cfg --- apiVersion: extensions/v1beta1 kind: DaemonSet metadata: name: kube-flannel-ds-s390x namespace: kube-system labels: tier: node app: flannel spec: template: metadata: labels: tier: node app: flannel spec: hostNetwork: true nodeSelector: beta.kubernetes.io/arch: s390x tolerations: - operator: Exists effect: NoSchedule serviceAccountName: flannel initContainers: - name: install-cni image: quay.io/coreos/flannel:v0.11.0-s390x 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:v0.11.0-s390x command: - /opt/bin/flanneld args: - --ip-masq - --kube-subnet-mgr resources: requests: cpu: "100m" memory: "50Mi" limits: cpu: "100m" memory: "50Mi" securityContext: privileged: true env: - name: POD_NAME valueFrom: fieldRef: fieldPath: metadata.name - name: POD_NAMESPACE valueFrom: fieldRef: fieldPath: metadata.namespace volumeMounts: - name: run mountPath: /run - name: flannel-cfg mountPath: /etc/kube-flannel/ volumes: - name: run hostPath: path: /run - name: cni hostPath: path: /etc/cni/net.d - name: flannel-cfg configMap: name: kube-flannel-cfg