導讀
經過前面k8s系列的文章，這一系列已經基本完成，現在就用幾篇文章說一下日常的叢集維護。
目錄
更新資源物件的Label
Namespace：叢集環境共享與隔離
部署叢集監控
部署Web UI管理叢集：Dashboard
更新資源物件的Label
比如對Pod進行Label的增刪改。
新增：
kubectl label pod pod-name key=value
修改：
kubelet label pod pod-name key=value --overwrite
刪除
kubelet label pod pod-name label_key
Namespace：叢集環境共享與隔離
不同的工作組可以在同一個k8s叢集中工作，k8s通過名稱空間和Context的設定對不同的工作組進行區分，讓它們可以在同一個k8s叢集中工作
（1）定義Context
需要為每個工作組分別設定一個Context，即執行環境，這個執行環境屬於某個名稱空間
通過kubectl context set-context命令定義Context，並將Context置於某個名稱空間中
例如：建立一個名為context-test1的context，繫結名稱空間context-text
建立一個叢集名稱：
kubectl config set-cluster kubernetes --server=https://localhost:8080 kubectl config set-context context-test1 --namespace=context-text --cluster=kubernetes
使用kubectl config view命令檢視已定義的Context（不知道叢集名也可以使用此命令檢視）
kubectl config view
通過kubectl config命令在${HOME}/.kube目錄下生成了一個名為config的檔案，檔案的內容為以kubectl config view命令檢視到的內容。所以也可以通過手工編輯該檔案的方式來設定Context。
（2）設定工作組在特定Context環境工作
使用如下命令設定當前執行環境
kubectl config use-context context-test1
之後所有操作都會在context-test1環境繫結的名稱空間中完成。
部署叢集監控
在Kubernetes新的監控體系中，Metrics Server用於提供核心指標（Core Metrics），包括Node、Pod的CPU和記憶體使用指標。對其他自定義指標（Custom Metrics）的監控則由Prometheus等元件來完成。
通過Metrics Server監控Pod和Node的CPU和記憶體資源使用資料。
Metrics Server在部署完成後，將通過Kubernetes核心API Server的“/apis/metrics.k8s.io/v1beta1”路徑提供Pod和Node的監控資料。Metrics Server原始碼和部署配置可以在GitHub程式碼庫（https://github.com/kubernetes-incubator/metrics-server）找到。
首先，部署Metrics Server例項，
從https://github.com/kubernetes-sigs/metrics-server/releases/download/v0.3.7/components.yaml獲取到最新的yaml檔案，
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
name: system:aggregated-metrics-reader
labels:
rbac.authorization.k8s.io/aggregate-to-view: "true"
rbac.authorization.k8s.io/aggregate-to-edit: "true"
rbac.authorization.k8s.io/aggregate-to-admin: "true"
rules:
- apiGroups: ["metrics.k8s.io"]
resources: ["pods", "nodes"]
verbs: ["get", "list", "watch"]
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
name: metrics-server:system:auth-delegator
roleRef:
apiGroup: rbac.authorization.k8s.io
kind: ClusterRole
name: system:auth-delegator
subjects:
- kind: ServiceAccount
name: metrics-server
namespace: kube-system
---
apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
name: metrics-server-auth-reader
namespace: kube-system
roleRef:
apiGroup: rbac.authorization.k8s.io
kind: Role
name: extension-apiserver-authentication-reader
subjects:
- kind: ServiceAccount
name: metrics-server
namespace: kube-system
---
apiVersion: apiregistration.k8s.io/v1beta1
kind: APIService
metadata:
name: v1beta1.metrics.k8s.io
spec:
service:
name: metrics-server
namespace: kube-system
group: metrics.k8s.io
version: v1beta1
insecureSkipTLSVerify: true
groupPriorityMinimum: 100
versionPriority: 100
---
apiVersion: v1
kind: ServiceAccount
metadata:
name: metrics-server
namespace: kube-system
---
apiVersion: apps/v1
kind: Deployment
metadata:
name: metrics-server
namespace: kube-system
labels:
k8s-app: metrics-server
spec:
selector:
matchLabels:
k8s-app: metrics-server
template:
metadata:
name: metrics-server
labels:
k8s-app: metrics-server
spec:
serviceAccountName: metrics-server
volumes:
# mount in tmp so we can safely use from-scratch images and/or read-only containers
- name: tmp-dir
emptyDir: {}
containers:
- name: metrics-server
image: yakdhane/metrics-server:v0.3.7
imagePullPolicy: IfNotPresent
args:
- --cert-dir=/tmp
- --secure-port=4443
command:
- /metrics-server
- --metric-resolution=30s
- --kubelet-insecure-tls
- --kubelet-preferred-address-types=InternalIP
ports:
- name: main-port
containerPort: 4443
protocol: TCP
securityContext:
readOnlyRootFilesystem: true
runAsNonRoot: true
runAsUser: 1000
volumeMounts:
- name: tmp-dir
mountPath: /tmp
nodeSelector:
kubernetes.io/os: linux
---
apiVersion: v1
kind: Service
metadata:
name: metrics-server
namespace: kube-system
labels:
kubernetes.io/name: "Metrics-server"
kubernetes.io/cluster-service: "true"
spec:
selector:
k8s-app: metrics-server
ports:
- port: 443
protocol: TCP
targetPort: main-port
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
name: system:metrics-server
rules:
- apiGroups:
- ""
resources:
- pods
- nodes
- nodes/stats
- namespaces
- configmaps
verbs:
- get
- list
- watch
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
name: system:metrics-server
roleRef:
apiGroup: rbac.authorization.k8s.io
kind: ClusterRole
name: system:metrics-server
subjects:
- kind: ServiceAccount
name: metrics-server
namespace: kube-system
yaml檔案需要修改，新增以下內容：
如果不新增上述內容，啟動會報錯
- --kubelet-preferred-address-types 改為支援ip通訊，InternalIP(default [Hostname,InternalDNS,InternalIP,ExternalDNS,ExternalIP])
- --kubelet-insecure-tls 忽略證書錯誤
在部署完成後確保metrics-server的Pod啟動成功：
kubectl -n kube-system get pod -l k8s-app=metrics-server
使用kubectl top nodes和kubectl top pods命令監控CPU和記憶體資源的使用情況：
Metrics Server提供的資料也可以供HPA控制器使用，以實現基於CPU使用率或記憶體使用值的Pod自動擴縮容功能。
部署Web UI管理叢集
Kubernetes的Web UI網頁管理工具kubernetes-dashboard可提供部署應用、資源物件管理、容器日誌查詢、系統監控等常用的叢集管理功能。為了在頁面上顯示系統資源的使用情況，要求部署Metrics Server。
可通過https://rawgit.com/kubernetes/dashboard/master/src/deploy/kubernetes-dashboard.yaml頁面下載部署kubernetes- dashboard的YAML配置檔案。
其中包含Deployment和Service的定義：
# 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.
apiVersion: v1
kind: Namespace
metadata:
name: kubernetes-dashboard
---
apiVersion: v1
kind: ServiceAccount
metadata:
labels:
k8s-app: kubernetes-dashboard
name: kubernetes-dashboard
namespace: kubernetes-dashboard
---
kind: Service
apiVersion: v1
metadata:
labels:
k8s-app: kubernetes-dashboard
name: kubernetes-dashboard
namespace: kubernetes-dashboard
spec:
type: NodePort
ports:
- port: 443
targetPort: 8443
nodePort: 9090
selector:
k8s-app: kubernetes-dashboard
---
apiVersion: v1
kind: Secret
metadata:
labels:
k8s-app: kubernetes-dashboard
name: kubernetes-dashboard-certs
namespace: kubernetes-dashboard
type: Opaque
---
apiVersion: v1
kind: Secret
metadata:
labels:
k8s-app: kubernetes-dashboard
name: kubernetes-dashboard-csrf
namespace: kubernetes-dashboard
type: Opaque
data:
csrf: ""
---
apiVersion: v1
kind: Secret
metadata:
labels:
k8s-app: kubernetes-dashboard
name: kubernetes-dashboard-key-holder
namespace: kubernetes-dashboard
type: Opaque
---
kind: ConfigMap
apiVersion: v1
metadata:
labels:
k8s-app: kubernetes-dashboard
name: kubernetes-dashboard-settings
namespace: kubernetes-dashboard
---
kind: Role
apiVersion: rbac.authorization.k8s.io/v1
metadata:
labels:
k8s-app: kubernetes-dashboard
name: kubernetes-dashboard
namespace: kubernetes-dashboard
rules:
# Allow Dashboard to get, update and delete Dashboard exclusive secrets.
- apiGroups: [""]
resources: ["secrets"]
resourceNames: ["kubernetes-dashboard-key-holder", "kubernetes-dashboard-certs", "kubernetes-dashboard-csrf"]
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.
- apiGroups: [""]
resources: ["services"]
resourceNames: ["heapster", "dashboard-metrics-scraper"]
verbs: ["proxy"]
- apiGroups: [""]
resources: ["services/proxy"]
resourceNames: ["heapster", "http:heapster:", "https:heapster:", "dashboard-metrics-scraper", "http:dashboard-metrics-scraper"]
verbs: ["get"]
---
kind: ClusterRole
apiVersion: rbac.authorization.k8s.io/v1
metadata:
labels:
k8s-app: kubernetes-dashboard
name: kubernetes-dashboard
rules:
# Allow Metrics Scraper to get metrics from the Metrics server
- apiGroups: ["metrics.k8s.io"]
resources: ["pods", "nodes"]
verbs: ["get", "list", "watch"]
---
apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
labels:
k8s-app: kubernetes-dashboard
name: kubernetes-dashboard
namespace: kubernetes-dashboard
roleRef:
apiGroup: rbac.authorization.k8s.io
kind: Role
name: kubernetes-dashboard
subjects:
- kind: ServiceAccount
name: kubernetes-dashboard
namespace: kubernetes-dashboard
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
name: kubernetes-dashboard
roleRef:
apiGroup: rbac.authorization.k8s.io
kind: ClusterRole
name: kubernetes-dashboard
subjects:
- kind: ServiceAccount
name: kubernetes-dashboard
namespace: kubernetes-dashboard
---
kind: Deployment
apiVersion: apps/v1
metadata:
labels:
k8s-app: kubernetes-dashboard
name: kubernetes-dashboard
namespace: kubernetes-dashboard
spec:
replicas: 1
revisionHistoryLimit: 10
selector:
matchLabels:
k8s-app: kubernetes-dashboard
template:
metadata:
labels:
k8s-app: kubernetes-dashboard
spec:
containers:
- name: kubernetes-dashboard
image: kubernetesui/dashboard:v2.0.0-rc3
imagePullPolicy: Always
ports:
- containerPort: 8443
protocol: TCP
args:
- --auto-generate-certificates
- --namespace=kubernetes-dashboard
# 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
securityContext:
allowPrivilegeEscalation: false
readOnlyRootFilesystem: true
runAsUser: 1001
runAsGroup: 2001
volumes:
- name: kubernetes-dashboard-certs
secret:
secretName: kubernetes-dashboard-certs
- name: tmp-volume
emptyDir: {}
serviceAccountName: kubernetes-dashboard
nodeSelector:
"beta.kubernetes.io/os": linux
# Comment the following tolerations if Dashboard must not be deployed on master
tolerations:
- key: node-role.kubernetes.io/master
effect: NoSchedule
---
kind: Service
apiVersion: v1
metadata:
labels:
k8s-app: dashboard-metrics-scraper
name: dashboard-metrics-scraper
namespace: kubernetes-dashboard
spec:
ports:
- port: 8000
targetPort: 8000
selector:
k8s-app: dashboard-metrics-scraper
---
kind: Deployment
apiVersion: apps/v1
metadata:
labels:
k8s-app: dashboard-metrics-scraper
name: dashboard-metrics-scraper
namespace: kubernetes-dashboard
spec:
replicas: 1
revisionHistoryLimit: 10
selector:
matchLabels:
k8s-app: dashboard-metrics-scraper
template:
metadata:
labels:
k8s-app: dashboard-metrics-scraper
annotations:
seccomp.security.alpha.kubernetes.io/pod: 'runtime/default'
spec:
containers:
- name: dashboard-metrics-scraper
image: kubernetesui/metrics-scraper:v1.0.3
ports:
- containerPort: 8000
protocol: TCP
livenessProbe:
httpGet:
scheme: HTTP
path: /
port: 8000
initialDelaySeconds: 30
timeoutSeconds: 30
volumeMounts:
- mountPath: /tmp
name: tmp-volume
securityContext:
allowPrivilegeEscalation: false
readOnlyRootFilesystem: true
runAsUser: 1001
runAsGroup: 2001
serviceAccountName: kubernetes-dashboard
nodeSelector:
"beta.kubernetes.io/os": linux
# Comment the following tolerations if Dashboard must not be deployed on master
tolerations:
- key: node-role.kubernetes.io/master
effect: NoSchedule
volumes:
- name: tmp-volume
emptyDir: {}
這裡，Service設定了NodePort對映到物理機的埠號，用於客戶端瀏覽器訪問。
建立ServiceAccount，ClusterRoleBinding，繫結cluster-admin的ClusterRole，允許訪問所有資源。
---
apiVersion: v1
kind: ServiceAccount
metadata:
labels:
k8s-app: kubernetes-dashboard
name: kubernetes-dashboard-admin
namespace: kube-system
---
apiVersion: rbac.authorization.k8s.io/v1beta1
kind: ClusterRoleBinding
metadata:
name: kubernetes-dashboard-admin
labels:
k8s-app: kubernetes-dashboard
roleRef:
apiGroup: rbac.authorization.k8s.io
kind: ClusterRole
name: cluster-admin
subjects:
- kind: ServiceAccount
name: kubernetes-dashboard-admin
namespace: kube-system
開啟瀏覽器，輸入某Node的IP和9090埠號，例如https://cnode-1:9090/#/login，就能訪問Dashboard的頁面了
選擇Token方式登陸，
利用下列命令獲取Token：
kubectl -n kube-system describe secret $(kubectl -n kube-system get secret | grep kubernetes-dashboard-admin-token | awk '{print $1}')
登入之後就可以看到叢集的全部資訊了（包括對資源的增刪改查等管理）：
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