K8s Dashboard和coredns安装及常用命令

一.部署Web UI（Dashboard）
1.解压包，进入目录
包就在之前的master部署组件里
这里里面kubernetes-server-linux-amd64.tar.gz

2.执行yaml文件

查看启动的pod，没在默认命名空间，在kube-system下

注：
其中dashboard-controller.yaml这个里面的dashboard镜像是国外的，如果慢，可以换成国内的镜像地址 image: registry.cn-hangzhou.aliyuncs.com/google_containers/kubernetes-dashboard-amd64:v1.10.0

3.创建Dashboard服务

4.查看启动的Dashboard服务

外网访问的是端口是44721

5.设置登陆令牌，访问web界面
创建用户访问，绑定集群管理员，使用它产生的密钥

创建账户产生的token

查看token

复制token到页面上即可

二.coredns的安装
安装coredns的yaml文档可以在kubernetes的github上找到https://github.com/kubernetes/kubernetes/edit/master/cluster/addons/dns/coredns/coredns.yaml.sed

[root@master ~]# vim coredns.yaml

 # Warning: This is a file generated from the base underscore template file: coredns.yaml.base

apiVersion: v1
kind: ServiceAccount
metadata:
name: coredns
namespace: kube-system
labels:
kubernetes.io/cluster-service: "true"
addonmanager.kubernetes.io/mode: Reconcile

apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
labels:
kubernetes.io/bootstrapping: rbac-defaults
addonmanager.kubernetes.io/mode: Reconcile
name: system:coredns
rules:

• apiGroups:
  • ""
    resources:
  • endpoints
  • services
  • pods
  • namespaces
    verbs:
  • list
  • watch
• apiGroups:
  • ""
    resources:
  • nodes
    verbs:

  • get

    apiVersion: rbac.authorization.k8s.io/v1
    kind: ClusterRoleBinding
    metadata:
    annotations:
    rbac.authorization.kubernetes.io/autoupdate: "true"
    labels:
    kubernetes.io/bootstrapping: rbac-defaults
    addonmanager.kubernetes.io/mode: EnsureExists
    name: system:coredns
    roleRef:
    apiGroup: rbac.authorization.k8s.io
    kind: ClusterRole
    name: system:coredns
    subjects:

• kind: ServiceAccount
  name: coredns
  namespace: kube-system

  apiVersion: v1
  kind: ConfigMap
  metadata:
  name: coredns
  namespace: kube-system
  labels:
  addonmanager.kubernetes.io/mode: EnsureExists
  data:
  Corefile: |
  .:53 {
  errors
  health
  kubernetes cluster.local in-addr.arpa ip6.arpa {
  pods insecure
  upstream
  fallthrough in-addr.arpa ip6.arpa
  }
  prometheus :9153
  proxy . /etc/resolv.conf
  cache 30
  loop
  reload
  loadbalance
  }

  apiVersion: extensions/v1beta1
  kind: Deployment
  metadata:
  name: coredns
  namespace: kube-system
  labels:
  k8s-app: kube-dns
  kubernetes.io/cluster-service: "true"
  addonmanager.kubernetes.io/mode: Reconcile
  kubernetes.io/name: "CoreDNS"
  spec:

  replicas: not specified here:

   # 1. In order to make Addon Manager do not reconcile this replicas parameter.
      # 2. Default is 1.
           # 3. Will be tuned in real time if DNS horizontal auto-scaling is turned on.

  strategy:
  type: RollingUpdate
  rollingUpdate:
  maxUnavailable: 1
  selector:
  matchLabels:
  k8s-app: kube-dns
  template:
  metadata:
  labels:
  k8s-app: kube-dns
  annotations:
  seccomp.security.alpha.kubernetes.io/pod: 'docker/default'
  spec:
  serviceAccountName: coredns
  tolerations:

  • key: "CriticalAddonsOnly"
    operator: "Exists"
    containers:
    • name: coredns
      image: coredns/coredns:1.2.6
      imagePullPolicy: IfNotPresent
      resources:
      limits:
      memory: 170Mi
      requests:
      cpu: 100m
      memory: 70Mi
      args: [ "-conf", "/etc/coredns/Corefile" ]
      volumeMounts:
  • name: config-volume
    mountPath: /etc/coredns
    readOnly: true
    ports:
  • containerPort: 53
    name: dns
    protocol: UDP
  • containerPort: 53
    name: dns-tcp
    protocol: TCP
  • containerPort: 9153
    name: metrics
    protocol: TCP
    livenessProbe:
    httpGet:
    path: /health
    port: 8080
    scheme: HTTP
    initialDelaySeconds: 60
    timeoutSeconds: 5
    successThreshold: 1
    failureThreshold: 5
    securityContext:
    allowPrivilegeEscalation: false
    capabilities:
    add:
    • NET_BIND_SERVICE
      drop:
    • all
      readOnlyRootFilesystem: true
      dnsPolicy: Default
      volumes:
  • name: config-volume
    configMap:
    name: coredns
    items:

    • key: Corefile
      path: Corefile

      apiVersion: v1
      kind: Service
      metadata:
      name: kube-dns
      namespace: kube-system
      annotations:
      prometheus.io/port: "9153"
      prometheus.io/scrape: "true"
      labels:
      k8s-app: kube-dns
      kubernetes.io/cluster-service: "true"
      addonmanager.kubernetes.io/mode: Reconcile
      kubernetes.io/name: "CoreDNS"
      spec:
      selector:
      k8s-app: kube-dns
      clusterIP: 10.0.0.2
      ports:

      • name: dns
        port: 53
        protocol: UDP
      • name: dns-tcp
        port: 53
        protocol: TCP

1.部署coredns

2.查看部署dns结果
[root@master ~]# kubectl get pods -n kube-system

3.测试可以解析到集群里的服务

不同命名空间解析
后面加上命名空间.svc.cluster.local

三.kubectl管理工具

1.删除
先删除控制器，再删服务

[root@master ~]# kubectl delete deployment.apps/nginx
[root@master ~]# kubectl delete service/nginx

2.在默认命名空间下创建nginx容器
[root@master ~]# kubectl run nginx --image=nginx --replicas=3 --labels="app=nignx-example" --image=nginx:1.10 --port=80
查看pod
[root@master ~]# kubectl get all

3.查看pod的详细信息describe
[root@master ~]# kubectl describe pod/nginx-7cfb59d88d-nmtp9

下面还有事件，可以用于排错

4.查看pod和service
[root@master ~]# kubectl get pod
[root@master ~]# kubectl get svc

5.显示标签
[root@master ~]# kubectl get pods --show-labels

注：设置标签的好处，到时候pod多了，可以指定pod的标签查找

6.查询pod的详细信息
[root@master ~]# kubectl get pods -o wide

7.查看控制用到的那些镜像
[root@master ~]# kubectl get deployment -o wide

8.启动发布服务
[root@master ~]# kubectl expose deployment nginx --port=88 --type=NodePort --target-port=80 --name=nginx-service

expose暴露服务
--port=88 外部ba暴露端口
type=NodePort 使用节点端口访问应用
--target-port=80 内部端口
--name=nginx-service 服务名称

通过集群ip加外部暴露端口可以在任意节点访问应用

或者通过node端口和节点地址地址访问

四.故障排查
1.查看pod详细信息
kubectl describe 容器pod id

2.查看pod日志
kubectl log 容器pod id

3.进入到pod查看情况
kubectl exec -it pod id bash

五.更新镜像
kubectl set --help 这个命令更新设置容器的设置
1.更新镜像版本

将之前的nginx1.10跟新为nginx1.11版本

这个过程是将之前的1.10版本的3个镜像删除，在创建3个1.11版本的镜像

查看刚创建的pod详细信息，已经变成nginx:1.11
[root@master ~]# kubectl describe pod nginx-799f6b8cfc-khbvf

2.还有另一种的办法更新镜像，直接编辑控制器资源文件
[root@master ~]# kubectl edit deploy/nginx

查看新创建的pod信息显示image是nginx:1.12

3.可以查看版本历史
[root@master ~]# kubectl rollout status deploy/nginx
[root@master ~]# kubectl rollout history deploy/nginx
再次升级为nginx:1.13

更新完成

history可以查看之前的记录

4.回滚状态
现在版本是nginx:1.13,假设这个版本有问题，要根据history回滚到之前的版本

[root@master ~]# kubectl rollout undo deployment.apps/nginx
[root@master ~]# kubectl rollout status deploy/nginx

查看版本历史，少了第三个版本，已经回滚到nginx:1.12了

查看新pod详细信息已经是1.12了

六.扩容副本scale
由于高并发业务需要将后端pod扩展为5个（现在为3个）
[root@master ~]# kubectl scale deployment.apps/nginx --replicas=5

业务下来了还可以缩容