Kubernetes之二workload資源編排

時間 2019-12-10

標籤 kubernetes 之二 workload 資源編排简体版

原文原文鏈接

資源配置清單用編排yaml的方式來編排Docker，採用RTETful的接口風格，主要的資源對象以下圖
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自主式Pod資源（不受控制器控制）

資源的清單格式：
    一級字段：apiVersion(group/version), kind, metadata(name,namespace,labels,annotations, ...), spec, status（只讀）
Pod資源：
    spec.containers <[]object>
     - name <string>
      image <string>
      imagePullPolicy  <string>
        Always, Never, IfNotPresent

    修改鏡像中的默認應用：
        command, args （容器的https://kubernetes.io/docs/tasks/inject-data-application/define-command-argument-container/ ）

標籤：（重要特性）
        key=value
            key: 字母、數字、_、-、.
            value：能夠爲空，只能字母或數字開頭及結尾，中間可以使用字母、數字、_、-、.
        例子：
           # kubectl get pods -l app (app是key值)
           # kubectl get pods --show-labels
           # kubectl label pods pod-demo release=canary --overwrite
           # kubectl get pods -l release=canary
            
標籤選擇器：
        等值關係：=，==，!=
        集合關係：
            KEY in (VALUE1,VALUE2,...)
            KEY notin (VALUE1,VALUE2,...)
            KEY
            !KEY
       許多資源支持內嵌字段定義其使用的標籤選擇器：
        matchLabels：直接給定鍵值
        matchExpressions：基於給定的表達式來定義使用標籤選擇器，{key:"KEY", operator:"OPERATOR", values:[VAL1,VAL2,...]}
            操做符：
                In, NotIn：values字段的值必須爲非空列表；
                Exists, NotExists：values字段的值必須爲空列表；
nodeSelector <map[string]string>
    節點標籤選擇器，能夠影響調度算法。

nodeName <string>

annotations:
    與label不一樣的地方在於，它不能用於挑選資源對象，僅用於爲對象提供「元數據」。

Pod生命週期

狀態：Pending, Running, Failed, Succeeded, Unknown
建立Pod經歷的過程：->apiServer->etcd保存->scheculer->etcd調度結果->當前節點運行pod（把狀態發回apiServer）->etcd保存
Pod生命週期中的重要行爲：
      1. 初始化容器
      2. 容器探測：
          liveness
          readiness (在生產環境中是必須配置的)
      3. 探針類型有三種：
          ExecAction、TCPSocketAction、HTTPGetAction
          # kubectl explain pod.spec.containers.livenessProbe
      4. restartPolicy:
          Always, OnFailure, Never. Default to Always.
      5. lifecycle
          # kubectl explain pods.spec.containers.lifecycle.preStop
          # kubectl explain pods.spec.containers.lifecycle.preStart

例子1， ExecAction探測

# vim liveness-pod.yaml
    apiVersion: v1
    kind: Pod
    metadata:
      name: liveness-exec-pod
      namespace: default
    spec:
      containers:
      - name: liveness-exec-container
        image: busybox:latest
        imagePullPolicy: IfNotPresent
        command: ["/bin/sh","-c","touch /tmp/healthy; sleep 30; rm -f /tmp/healthy; sleep 3600"]
        livenessProbe:
           exec:
             command: ["test","-e","/tmp/healthy"]
        initialDelaySeconds: 1
        periodSeconds: 3
# kubectl create -f liveness-pod.yaml
#  kubectl describe pod liveness-exec-pod
      State:          Running
      Started:      Thu, 09 Aug 2018 01:39:11 -0400
      Last State:     Terminated
      Reason:       Error
      Exit Code:    137
      Started:      Thu, 09 Aug 2018 01:38:03 -0400
      Finished:     Thu, 09 Aug 2018 01:39:09 -0400
      Ready:          True
      Restart Count:  1
      Liveness:       exec [test -e /tmp/healthy] delay=1s timeout=1s period=3s #success=1 #failure=3

例子2， HTTPGetAction探測

# vim liveness-http.yaml
    apiVersion: v1
    kind: Pod
    metadata:
      name: liveness-httpget-pod
      namespace: default
    spec:
      containers:
      - name: liveness-httpget-container
        image: ikubernetes/myapp:v1
        imagePullPolicy: IfNotPresent
    ports:
    - name: http
      containerPort: 80
    livenessProbe:
       httpGet:
             port: http
             path: /index.html
   initialDelaySeconds: 1
   periodSeconds: 3
# kubectl create -f liveness-http.yaml
# kubectl exec -it liveness-httpget-pod -- /bin/sh
    rm /usr/share/nginx/html/index.html
# kubectl describe pod liveness-httpget-pod
     Restart Count:  1
        Liveness:       http-get http://:http/index.html delay=1s timeout=1s period=3s #success=1 #failure=3

例子3 readiness的HTTPGetAction探測

# vim readiness-http.yaml
    apiVersion: v1
    kind: Pod
    metadata:
      name: readiness-httpget-pod
      namespace: default
    spec:
      containers:
      -  name: readiness-httpget-container
      image: ikubernetes/myapp:v1
      imagePullPolicy: IfNotPresent
    ports:
    - name: http
    containerPort: 80
   readinessProbe:
     httpGet:
       port: http
       path: /index.html
   initialDelaySeconds: 1
   periodSeconds: 3
#kubectl create -f readiness-http.yaml
# kubectl exec -it readiness-httpget-pod -- /bin/sh
    / # rm -f /usr/share/nginx/html/index.html
# kubectl get pods -w
    readiness-httpget-pod   0/1       Running   0          1m
    此docker的狀態是0，不會對外提供服務

例子4 lifetime的postStar啓動以後當即執行

# vim pod-postStart.yaml
    apiVersion: v1
    kind: Pod
    metadata:
          name: poststart-pod
          namespace: default
    spec:
      containers:
      - name: busybox-httpd
      image: busybox:latest
      imagePullPolicy: IfNotPresent
    lifecycle:
         postStart:
           exec:
         command: ['/bin/sh','-c','echo Home_Page >> /tmp/index.html']
    command: ['/bin/httpd']
    args: ['-f','-h /tmp']

Pod控制器

管理pod的中間層，運行於咱們期待的狀態。

ReplicaSet：

自動擴容和縮容，取代了以前的ReplicationController，用於管理無狀態的docker。Google不建議直接使用
    1. 用戶指望的pod副本
    2. label標籤選擇器，用於管理pod副本
    3. 新建pod根據pod template

ReplicaSet實例：

1.  vim replicaset.yaml
    apiVersion: apps/v1
    kind: ReplicaSet
    metadata:
        name: myapp
        namespace: default
    spec:
        replicas: 2
        selector:
            matchLabels:
                    app: myapp
                    release: canary
        template:
            metadata:
                    name: myapp-pod
                    labels:
                            app: myapp
                            release: canary
                            environment: qa
            spec:
                    containers:
                    - name: myapp-container
                      image: ikubernetes/myapp:v1
                      ports:
                      - name: http
                        containerPort: 80
2. kubectl create -f replicaset.yaml
3. kubectl get pods
    NAME          READY     STATUS    RESTARTS   AGE
    myapp-c6f58   1/1       Running   0          3s
    myapp-lvjk2   1/1       Running   0          3s
4. kubectl delete pod myapp-c6f58
5.  kubectl get pods (生成一個新的pod)
    NAME          READY     STATUS    RESTARTS   AGE
    myapp-lvjk2   1/1       Running   0          2m
    myapp-s9hgr   1/1       Running   0          10s
6. kubectl edit rs myapp
    replicas: 2改成5
7. kubectl get pods (pod自動增加爲5個）
    NAME          READY     STATUS    RESTARTS   AGE
    myapp-h2j68   1/1       Running   0          5s
    myapp-lvjk2   1/1       Running   0          8m
    myapp-nsv6z   1/1       Running   0          5s
    myapp-s9hgr   1/1       Running   0          6m
    myapp-wnf2b   1/1       Running   0          5s
    # curl 10.244.2.17
    Hello MyApp | Version: v1 | <a href="hostname.html">Pod Name</a>
8. kubectl get pods
    ikubernetes/myapp:v1更改成v2
    此時運行着的docker不會自到升級
    刪除一個pod
    # kubectl delete pod myapp-h2j68
    新的docker myapp-4qg8c 已經升級爲v2
      # curl 10.244.2.19
        Hello MyApp | Version: v2 | <a href="hostname.html">Pod Name</a>
    只刪除一個在線pod，新生成的pod會爲新的版本，這種叫金絲雀發佈。
    依次把全部舊版本的pod刪除，新版本的pod自動生成，這種是灰度發佈，此種發佈要注意系統負載的變化。
    還有一種發佈方式是藍綠髮布，以下圖

一批徹底更新完。如出一轍的環境。新建立一個RS2，刪除RS1，或者，建立RS2，和RS1並行，更改service，全指向RS2node

Deployment

經過控制ReplicaSet來控制pod，能提供比ReplicaSet更強大的功能。支持滾動更新和回滾。支持更新節奏和更新邏輯。

# kubectl explain deploy
    KIND:     Deployment
    VERSION:  extensions/v1beta1 （文檔的顯示落後於功能，最新apps/v1）
# kubectl explain deploy.spec.strategy
    rollingUpdate (控制更新粒度)
# kubectl explain deploy.spec.strategy.rollingUpdate
    maxSurge （）
    maxUnavailable （最多幾個不可用）
    兩個不可能同時爲零，即不能多也不能少。
# kubectl explain deploy.spec
     revisionHistoryLimit （保持多少個歷史）

Deployment實例

# vim deploy.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: myapp-deploy
  namespace: default
spec:
  replicas: 2
  selector:
    matchLabels:
        app: myapp
        release: canary
  template:
        metadata:
          labels:
            app: myapp
            release: canary
        spec:
          containers:
          - name: myapp
            image: ikubernetes/myapp:v1
            ports:
            - name: http
              containerPort: 80
# kubectl apply -f deploy.yaml
#  kubectl get rs
    NAME                      DESIRED   CURRENT   READY     AGE
    myapp-deploy-69b47bc96d   2         2         2         1m
    （69b47bc96d是模板的hash值）
# kubectl get pods
    NAME                            READY     STATUS    RESTARTS   AGE
    myapp-deploy-69b47bc96d-f4bp4   1/1       Running   0          3m
    myapp-deploy-69b47bc96d-qllnm   1/1       Running   0          3m
# 更改replicas: 3
# kubectl get pods
    NAME                            READY     STATUS    RESTARTS   AGE
    myapp-deploy-69b47bc96d-f4bp4   1/1       Running   0          4m
    myapp-deploy-69b47bc96d-qllnm   1/1       Running   0          4m
    myapp-deploy-69b47bc96d-s6t42   1/1       Running   0          17s
#  kubectl describe deploy myapp-deploy
    RollingUpdateStrategy:  25% max unavailable, 25% max surge （默認更新策略）
# kubectl get pod -w -l app=myapp （動態監控）
# 更改image: ikubernetes/myapp:v2
# kubectl apply -f deploy.yaml
#  kubectl get pod -w -l app=myapp （）
    NAME                            READY     STATUS    RESTARTS   AGE
    myapp-deploy-69b47bc96d-f4bp4   1/1       Running   0          6m
    myapp-deploy-69b47bc96d-qllnm   1/1       Running   0          6m
    myapp-deploy-69b47bc96d-s6t42   1/1       Running   0          2m
    myapp-deploy-67f6f6b4dc-tncmc   0/1       Pending   0         1s
    myapp-deploy-67f6f6b4dc-tncmc   0/1       Pending   0         1s
    myapp-deploy-67f6f6b4dc-tncmc   0/1       ContainerCreating   0         2s
    myapp-deploy-67f6f6b4dc-tncmc   1/1       Running   0         4s
# kubectl get rs （）
NAME                      DESIRED   CURRENT   READY     AGE
myapp-deploy-67f6f6b4dc   3         3         3         54s
myapp-deploy-69b47bc96d   0         0         0         8m
# kubectl rollout history deployment myapp-deploy 
#  kubectl patch deployment myapp-deploy -p '{"spec":{"replicas":5}}' 用patch方式更改replicas爲5
#  kubectl get pod -w -l app=myapp
    NAME                            READY     STATUS    RESTARTS   AGE
    myapp-deploy-67f6f6b4dc-fc7kj   1/1       Running   0          18s
    myapp-deploy-67f6f6b4dc-kssst   1/1       Running   0          5m
    myapp-deploy-67f6f6b4dc-tncmc   1/1       Running   0          5m
    myapp-deploy-67f6f6b4dc-xdzvc   1/1       Running   0          18s
    myapp-deploy-67f6f6b4dc-zjn77   1/1       Running   0          5m
#  kubectl patch deployment myapp-deploy -p '{"spec":{"strategy":{"rollingUpdate":{"maxSurge":1,"maxUnavaliable":0}}}}'
# kubectl describe deployment myapp-deploy
    RollingUpdateStrategy:  0 max unavailable, 1 max surge 
# 更新版本也可用setimage
     kubectl set image deployment myapp-deploy myapp=ikubernetes/myapp:v3 && kubectl rollout pause deployment myapp-deploy
#  kubectl rollout history deployment myapp-deploy
# kubectl rollout undo deployment myapp-deploy --to-revision=1 (回滾到初版本)

DaemonSet

確保只運行一個副本，運行在集羣中每個節點上。（也能夠部分節點上只運行一個且只有一個pod副本，如監控ssd硬盤）
# kubectl explain ds
# vim  filebeat.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: redis
  namespace: default
spec:
  replicas: 1
  selector:
    matchLabels:
      app: redis
      role: logstor
  template:
    metadata:
      labels:
        app: redis
        role: logstor
    spec:
      containers:
      - name: redis
        image: redis:4.0-alpine
        ports:
        - name: redis
          containerPort: 6379

apiVersion: apps/v1
    kind: DaemonSet
    metadata:
      name: myapp-ds
      namespace: default
    spec:
       selector:
       matchLabels:
                app: filebeat
                release: stable
       template:
        metadata:
          labels:
            app: filebeat
            release: stable
        spec:
          containers:
          - name: filebeat
            image: ikubernetes/filebeat:5.6.5-alpine
            env:
            - name: REDIS_HOST
              value: redis.default.svc.cluster.local
            - name: REDIS_LOG_LEVEL
              value: info
# kubectl apply -f filebeat.yaml
#  kubectl get pods -l app=filebeat -o wide (運行兩個是由於目前節點數爲2，默認不能運行在master，由於master有污點)
  filebeat-ds-chxl6   1/1       Running   1          8m        10.244.2.37   node2
    filebeat-ds-rmnxq   1/1       Running   0          8m        10.244.1.35   node1
# kubectl logs myapp-ds-r47zj
# kubectl expose deployment redis --port=6379
# kubectl describe ds filebeat
# 支持在線滾動更新
    kubectl set image daemonsets filebeat-ds filebeat=ikubernetes/filebeat:5.6.6-alpine
# kubectl explain pod.spec
    hostNetwork (DaemonSet能夠直接共享主機的網絡名稱，直接對外提供服務)

Job

按照用記指定的數量啓動N個pod資源，要不要從新建立取決於任務有沒有完成

Cronjob

週期任務

StatefulSet

有狀態應用，每個pod副本是單獨管理的。須要腳本，加入到模板中
TPR: Third Party Resource(1.2開始 1.7廢棄）
CDR：customer defined resource（1.8開始）
Operator：封裝（etcd,Prometheus只有幾個支持 ）

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