K8s Dashboard和coredns安裝及常用命令

一.部署Web UI（Dashboard）
1.解壓包，進入目錄
包就在之前的master部署組件裏
這裏裏面kubernetes-server-linux-amd64.tar.gz

2.執行yaml文件

查看啓動的pod，沒在默認命名空間，在kube-system下

注：
其中dashboard-controller.yaml這個裏面的dashboard鏡像是國外的，如果慢，可以換成國內的鏡像地址 image: registry.cn-hangzhou.aliyuncs.com/google_containers/kubernetes-dashboard-amd64:v1.10.0

3.創建Dashboard服務

4.查看啓動的Dashboard服務

外網訪問的是端口是44721

5.設置登陸令牌，訪問web界面
創建用戶訪問，綁定集羣管理員，使用它產生的密鑰

創建賬戶產生的token

查看token

複製token到頁面上即可

二.coredns的安裝
安裝coredns的yaml文檔可以在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結果
[root@master ~]# kubectl get pods -n kube-system

3.測試可以解析到集羣裏的服務

不同命名空間解析
後面加上命名空間.svc.cluster.local

三.kubectl管理工具

1.刪除
先刪除控制器，再刪服務

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

2.在默認命名空間下創建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的詳細信息describe
[root@master ~]# kubectl describe pod/nginx-7cfb59d88d-nmtp9

下面還有事件，可以用於排錯

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

5.顯示標籤
[root@master ~]# kubectl get pods --show-labels

注：設置標籤的好處，到時候pod多了，可以指定pod的標籤查找

6.查詢pod的詳細信息
[root@master ~]# kubectl get pods -o wide

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

8.啓動發佈服務
[root@master ~]# kubectl expose deployment nginx --port=88 --type=NodePort --target-port=80 --name=nginx-service

expose暴露服務
--port=88 外部ba暴露端口
type=NodePort 使用節點端口訪問應用
--target-port=80 內部端口
--name=nginx-service 服務名稱

通過集羣ip加外部暴露端口可以在任意節點訪問應用

或者通過node端口和節點地址地址訪問

四.故障排查
1.查看pod詳細信息
kubectl describe 容器pod id

2.查看pod日誌
kubectl log 容器pod id

3.進入到pod查看情況
kubectl exec -it pod id bash

五.更新鏡像
kubectl set --help 這個命令更新設置容器的設置
1.更新鏡像版本

將之前的nginx1.10跟新爲nginx1.11版本

這個過程是將之前的1.10版本的3個鏡像刪除，在創建3個1.11版本的鏡像

查看剛創建的pod詳細信息，已經變成nginx:1.11
[root@master ~]# kubectl describe pod nginx-799f6b8cfc-khbvf

2.還有另一種的辦法更新鏡像，直接編輯控制器資源文件
[root@master ~]# kubectl edit deploy/nginx

查看新創建的pod信息顯示image是nginx:1.12

3.可以查看版本歷史
[root@master ~]# kubectl rollout status deploy/nginx
[root@master ~]# kubectl rollout history deploy/nginx
再次升級爲nginx:1.13

更新完成

history可以查看之前的記錄

4.回滾狀態
現在版本是nginx:1.13,假設這個版本有問題，要根據history回滾到之前的版本

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

查看版本歷史，少了第三個版本，已經回滾到nginx:1.12了

查看新pod詳細信息已經是1.12了

六.擴容副本scale
由於高併發業務需要將後端pod擴展爲5個（現在爲3個）
[root@master ~]# kubectl scale deployment.apps/nginx --replicas=5

業務下來了還可以縮容

K8s Dashboard和coredns安裝及常用命令

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

get

kind: ServiceAccount
name: coredns
namespace: kube-system

replicas: not specified here:

key: Corefile
path: Corefile

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K8s Dashboard和coredns安裝及常用命令

apiVersion: v1kind: ServiceAccountmetadata:name: corednsnamespace: kube-systemlabels:kubernetes.io/cluster-service: "true"addonmanager.kubernetes.io/mode: Reconcile

get

kind: ServiceAccountname: corednsnamespace: kube-system

replicas: not specified here:

key: Corefilepath: Corefile

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

kind: ServiceAccount
name: coredns
namespace: kube-system

key: Corefile
path: Corefile