一.概念解释

Kubernetes的名字来自希腊语，意思是“舵手” 或 “领航员”。K8s是将8个字母“ubernete”替换为“8”的缩写。
Kubernetes是Google开源的一个容器编排引擎，它支持自动化部署、大规模可伸缩、应用容器化管理。在生产环境中部署一个应用程序时，通常要部署该应用的多个实例以便对应用请求进行负载均衡。
在Kubernetes中，我们可以创建多个容器，每个容器里面运行一个应用实例，然后通过内置的负载均衡策略，实现对这一组应用实例的管理、发现、访问，而这些细节都不需要运维人员去进行复杂的手工配置和处理。

特点：

• 可移植: 支持公有云，私有云，混合云，多重云（multi-cloud）
• 可扩展: 模块化，插件化，可挂载，可组合
• 自动化: 自动部署，自动重启，自动复制，自动伸缩/扩展

二.构建K8s管理集群

1.清除实验环境(server1、server2、server3操作相同)

• 清除列表管理(之前部署swarm的集群)

[root@server1 ~]# docker service ls
[root@server1 ~]# docker service rm web
[root@server1 ~]# docker stack rm portainer

• 清理卷

[root@server1 ~]# docker volume ls
[root@server1 ~]# docker volume prune 

• 删除容器

[root@server1 ~]# docker rm -f  `docker ps -aq`

• 删除网络

[root@server1 ~]# docker network ls
[root@server1 ~]# docker network rm we_net1

• 节点离开swarm集群

[root@server1 ~]# docker swarm leave -f

• 禁用swap分区

[root@server1 ~]# swapoff -a
[root@server1 ~]# vim /etc/fstab 

[root@server2 ~]# swapoff -a
[root@server2 ~]# vim /etc/fstab 

[root@server3 ~]# swapoff -a
[root@server3 ~]# vim /etc/fstab 

2.为server1,server2,server3安装软件包

[root@server1 ~]# ls
cri-tools-1.13.0-0.x86_64.rpm  kubectl-1.15.0-0.x86_64.rpm  kubernetes-cni-0.7.5-0.x86_64.rpm
kubeadm-1.15.0-0.x86_64.rpm    kubelet-1.15.0-0.x86_64.rpm
[root@server1 ~]# yum install * -y
[root@server1 ~]# scp * server2:
[root@server1 ~]# scp * server3:

[root@server2 ~]# ls
cri-tools-1.13.0-0.x86_64.rpm  kubectl-1.15.0-0.x86_64.rpm  kubernetes-cni-0.7.5-0.x86_64.rpm
kubeadm-1.15.0-0.x86_64.rpm    kubelet-1.15.0-0.x86_64.rpm
[root@server2 ~]# yum install *

[root@server3 ~]# ls
cri-tools-1.13.0-0.x86_64.rpm  kubectl-1.15.0-0.x86_64.rpm  kubernetes-cni-0.7.5-0.x86_64.rpm
kubeadm-1.15.0-0.x86_64.rpm    kubelet-1.15.0-0.x86_64.rpm
[root@server3 ~]# yum install * -y

3.所有节点导入相关镜像

[root@server1 ~]# for i in *.tar; do docker load -i $i ;done

4.将镜像传给server2、server3，并导入镜像

[root@server1 ~]# scp *.tar server2:
[root@server1 ~]# scp *.tar server3:

[root@server2 ~]# for i in *.tar; do docker load -i $i ;done

[root@server3 ~]# for i in *.tar; do docker load -i $i ;done

5.在所有节点的/etc/sysctl.d/k8s.conf内写入内容并查看

[root@server1 ~]# vim /etc/sysctl.d/k8s.conf
[root@server1 ~]# cat /etc/sysctl.d/k8s.conf
net.bridge.bridge-nf-call-ip6tables = 1
net.bridge.bridge-nf-call-iptables = 1
[root@server1 ~]# scp /etc/sysctl.d/k8s.conf server2:/etc/sysctl.d/
k8s.conf                                                                      100%   79     0.1KB/s   00:00    
[root@server1 ~]# scp /etc/sysctl.d/k8s.conf server3:/etc/sysctl.d/
k8s.conf           

[root@server1 ~]# sysctl --system
      

6.在server1，server2,server3开启kubelet服务（此时查看状态仍未开启）

[root@server1 ~]# systemctl start kubelet
[root@server1 ~]# systemctl enable kubelet

6.初始化管理节点

[root@server1 ~]# kubeadm init --pod-network-cidr=10.244.0.0/16 --apiserver-advertise-address=172.25.31.1

注意：如果第一次初始化集群失败，需要执行命令"kubeadm reset"进行重置，重置之后再执行初始化集群的命令，进行集群初始化。

7.创建用户kubeadm，并赋予所有权限

[root@server1 k8s]# useradd kubeadm
[root@server1 k8s]# vim /etc/sudoers

8.切换到kubeadm用户下创建文件并将其复制

[root@server1 ~]# su - kubeadm 
[kubeadm@server1 ~]$ mkdir -p $HOME/.kube
[kubeadm@server1 ~]$ sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
[kubeadm@server1 ~]$ sudo chown $(id -u):$(id -g) $HOME/.kube/config
[kubeadm@server1 ~]$ exit
logout

9.在server1上配置 kubectl 命令补齐功能:

[kubeadm@server1 ~]$ echo "source <(kubectl completion bash)" >> .bashrc
[kubeadm@server1 ~]$ logout
[root@server1 ~]# su - kubeadm 

10.在server1上将kube-flannel.yml文件发送到/home/k8s目录下。因为kube-flannel.yml文件原来的/root/k8s目录下，普通用户k8s无法访问

[root@server1 ~]# cp kube-flannel.yml /home/kubeadm/
[root@server1 ~]# su - kubeadm 
Last login: Fri Aug  9 14:25:33 CST 2019 on pts/0
[kubeadm@server1 ~]$ ls
kube-flannel.yml
[kubeadm@server1 ~]$ kubectl apply -f kube-flannel.yml
clusterrole.rbac.authorization.k8s.io/flannel created
clusterrolebinding.rbac.authorization.k8s.io/flannel created
serviceaccount/flannel created
configmap/kube-flannel-cfg created
daemonset.extensions/kube-flannel-ds-amd64 created
daemonset.extensions/kube-flannel-ds-arm64 created
daemonset.extensions/kube-flannel-ds-arm created
daemonset.extensions/kube-flannel-ds-ppc64le created
daemonset.extensions/kube-flannel-ds-s390x created

11.在所有节点导入flannel

[root@server1 ~]# docker load -i flannel.tar 
cd7100a72410: Loading layer  4.403MB/4.403MB
3b6c03b8ad66: Loading layer  4.385MB/4.385MB
93b0fa7f0802: Loading layer  158.2kB/158.2kB
4165b2148f36: Loading layer  36.33MB/36.33MB
b883fd48bb96: Loading layer   5.12kB/5.12kB
Loaded image: quay.io/coreos/flannel:v0.10.0-amd64
[root@server1 ~]# scp flannel.tar server2:
flannel.tar                             100%   43MB  43.2MB/s   00:00    
[root@server1 ~]# scp flannel.tar server3:
flannel.tar                             100%   43MB  43.2MB/s   00:0

server2:

[root@server2 ~]# docker load  -i flannel.tar 
cd7100a72410: Loading layer  4.403MB/4.403MB
3b6c03b8ad66: Loading layer  4.385MB/4.385MB
93b0fa7f0802: Loading layer  158.2kB/158.2kB
4165b2148f36: Loading layer  36.33MB/36.33MB
b883fd48bb96: Loading layer   5.12kB/5.12kB
Loaded image: quay.io/coreos/flannel:v0.10.0-amd64

server3：

[root@server3 ~]# docker load -i flannel.tar 
cd7100a72410: Loading layer  4.403MB/4.403MB
3b6c03b8ad66: Loading layer  4.385MB/4.385MB
93b0fa7f0802: Loading layer  158.2kB/158.2kB
4165b2148f36: Loading layer  36.33MB/36.33MB
b883fd48bb96: Loading layer   5.12kB/5.12kB
Loaded image: quay.io/coreos/flannel:v0.10.0-amd64

11.在server2和server3上加载ipvs内核模块并使其临时生效

[root@server2 ~]# modprobe ip_vs_wrr
[root@server2 ~]# modprobe ip_vs_rr
[root@server2 ~]# modprobe ip_vs_sh
[root@server2 ~]# modprobe ip_vs

[root@server3 ~]# modprobe ip_vs_wrr
[root@server3 ~]# modprobe ip_vs_rr
[root@server3 ~]# modprobe ip_vs_sh
[root@server3 ~]# modprobe ip_vs

12.server2、server3加入节点

[root@server3 ~]# kubeadm join 172.25.31.1:6443 --token pu2qxd.7i5itunef7xta8wg \
>     --discovery-token-ca-cert-hash sha256:d2999b6e117e399234cf47884a183229aabb834dc700ecacf42449c9d36a0074 

[root@server2 ~]# kubeadm join 172.25.31.1:6443 --token pu2qxd.7i5itunef7xta8wg \
>     --discovery-token-ca-cert-hash sha256:d2999b6e117e399234cf47884a183229aabb834dc700ecacf42449c9d36a0074 

13.获取默认namespace（default）下的pod，查看所有节点的状态是否都是ready，查看pods状态是否是running

[kubeadm@server1 ~]$ kubectl get nodes
[kubeadm@server1 ~]$ kubectl get pods --all-namespaces

14.查看master状态

[kubeadm@server1 ~]$ kubectl get cs
[kubeadm@server1 ~]$ kubectl get node
[kubeadm@server1 ~]$  kubectl get all -n kube-system

注意：
1.master节点要求cpu>=2
2.

三.布置UI界面

1.在所有节点导入kubernetes-dashboard.tar镜像

server1：
server2:
server3:

2.获取或者自己编写kubernetes-dashboard.yaml并发送到/home/kubeadm/

[root@server1 ~]# cp kubernetes-dashboard.yaml /home/kubeadm/
[root@server1 ~]# cd /home/kubeadm/
[root@server1 kubeadm]# ls
kube-flannel.yml  kubernetes-dashboard.yaml

# Copyright 2017 The Kubernetes Authors.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

# ------------------- Dashboard Secret ------------------- #

apiVersion: v1
kind: Secret
metadata:
  labels:
    k8s-app: kubernetes-dashboard
  name: kubernetes-dashboard-certs
  namespace: kube-system
type: Opaque

---
# ------------------- Dashboard Service Account ------------------- #

apiVersion: v1
kind: ServiceAccount
metadata:
  labels:
    k8s-app: kubernetes-dashboard
  name: kubernetes-dashboard
  namespace: kube-system

---
# ------------------- Dashboard Role & Role Binding ------------------- #

kind: Role
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: kubernetes-dashboard-minimal
  namespace: kube-system
rules:
  # Allow Dashboard to create 'kubernetes-dashboard-key-holder' secret.
- apiGroups: [""]
  resources: ["secrets"]
  verbs: ["create"]
  # Allow Dashboard to create 'kubernetes-dashboard-settings' config map.
- apiGroups: [""]
  resources: ["configmaps"]
  verbs: ["create"]
  # Allow Dashboard to get, update and delete Dashboard exclusive secrets.
- apiGroups: [""]
  resources: ["secrets"]
  resourceNames: ["kubernetes-dashboard-key-holder", "kubernetes-dashboard-certs"]
  verbs: ["get", "update", "delete"]
  # Allow Dashboard to get and update 'kubernetes-dashboard-settings' config map.
- apiGroups: [""]
  resources: ["configmaps"]
  resourceNames: ["kubernetes-dashboard-settings"]
  verbs: ["get", "update"]
  # Allow Dashboard to get metrics from heapster.
- apiGroups: [""]
  resources: ["services"]
  resourceNames: ["heapster"]
  verbs: ["proxy"]
- apiGroups: [""]
  resources: ["services/proxy"]
  resourceNames: ["heapster", "http:heapster:", "https:heapster:"]
  verbs: ["get"]

---
apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
  name: kubernetes-dashboard-minimal
  namespace: kube-system
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: Role
  name: kubernetes-dashboard-minimal
subjects:
- kind: ServiceAccount
  name: kubernetes-dashboard
  namespace: kube-system

---
# ------------------- Dashboard Deployment ------------------- #

kind: Deployment
apiVersion: apps/v1
metadata:
  labels:
    k8s-app: kubernetes-dashboard
  name: kubernetes-dashboard
  namespace: kube-system
spec:
  replicas: 1
  revisionHistoryLimit: 10
  selector:
    matchLabels:
      k8s-app: kubernetes-dashboard
  template:
    metadata:
      labels:
        k8s-app: kubernetes-dashboard
    spec:
      containers:
      - name: kubernetes-dashboard
        image: k8s.gcr.io/kubernetes-dashboard-amd64:v1.10.1
        ports:
        - containerPort: 8443
          protocol: TCP
        args:
          - --auto-generate-certificates
          # Uncomment the following line to manually specify Kubernetes API server Host
          # If not specified, Dashboard will attempt to auto discover the API server and connect
          # to it. Uncomment only if the default does not work.
          # - --apiserver-host=http://my-address:port
        volumeMounts:
        - name: kubernetes-dashboard-certs
          mountPath: /certs
          # Create on-disk volume to store exec logs
        - mountPath: /tmp
          name: tmp-volume
        livenessProbe:
          httpGet:
            scheme: HTTPS
            path: /
            port: 8443
          initialDelaySeconds: 30
          timeoutSeconds: 30
      volumes:
      - name: kubernetes-dashboard-certs
        secret:
          secretName: kubernetes-dashboard-certs
      - name: tmp-volume
        emptyDir: {}
      serviceAccountName: kubernetes-dashboard
      # Comment the following tolerations if Dashboard must not be deployed on master
      tolerations:
      - key: node-role.kubernetes.io/master
        effect: NoSchedule

---
# ------------------- Dashboard Service ------------------- #

kind: Service
apiVersion: v1
metadata:
  labels:
    k8s-app: kubernetes-dashboard
  name: kubernetes-dashboard
  namespace: kube-system
spec:
  ports:
    - port: 443
      targetPort: 8443
  selector:
    k8s-app: kubernetes-dashboard

3.切换用户

[root@server1 kubeadm]# su - kubeadm 
Last login: Fri Aug  9 14:57:20 CST 2019 on pts/0
[kubeadm@server1 ~]$ ls
kube-flannel.yml  kubernetes-dashboard.yaml
[kubeadm@server1 ~]$ vim kubernetes-dashboard.yaml 
[kubeadm@server1 ~]$ kubectl create -f kubernetes-dashboard.yaml 

4.更改type

[kubeadm@server1 ~]$ kubectl edit service kubernetes-dashboard -n kube-system
service/kubernetes-dashboard edited
##编辑类型type：NodePort

5.获取NodePort

[kubeadm@server1 ~]$ kubectl describe svc kubernetes-dashboard -n kube-system
[kubeadm@server1 ~]$ kubectl get pods -n kube-system 

6.新建用户，用来管理UI界面

[kubeadm@server1 ~]$ vim dashboard-admin.yaml
[kubeadm@server1 ~]$ kubectl create -f dashboard-admin.yaml 
serviceaccount/admin-user created
clusterrolebinding.rbac.authorization.k8s.io/admin-user created

文件内容：

apiVersion: v1
kind: ServiceAccount
metadata:
  name: admin-user
  namespace: kube-system

---

apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: admin-user
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: cluster-admin
subjects:
- kind: ServiceAccount
  name: admin-user
  namespace: kube-system

7.获取令牌（token）

[kubeadm@server1 ~]$ kubectl get secrets -n kube-system | grep admin
admin-user-token-zgt2v                           kubernetes.io/service-account-token   3      3m54s
[kubeadm@server1 ~]$ kubectl describe secrets admin-user-token-zgt2v -n kube-system

测试：

浏览器输入：https://172.25.31.1:31912

注意：

• 确保每个节点都加入镜像
• 每个节点都要有网关，并能上网，（刚开始要连网）