docker筆記24-pod控制器
上一節，我們建立的pod，是透過資源配置清單定義的，如果手工把這樣的pod刪除後，不會自己重新建立，這樣建立的pod叫自主式Pod。
在生產中，我們很少使用自主式pod。
下面我們學習另外一種pod，叫控制器管理的Pod，控制器會按照定義的策略嚴格控制pod的數量，一旦發現pod數量少了，會立即自動建立出來新的pod；一旦發現pod多了，也會自動殺死多餘的Pod。
pod控制器：ReplicaSet控制器、Deployment控制器（必須掌握）、DaenibSet控制器、Job控制器
ReplicaSet控制器
：替使用者建立指定數量Pod的副本，並保證pod副本滿足使用者期望的數量；而且更新自動擴縮容機制。
replicat主要由三個元件組成：1、使用者期望的pod副本數量；2、標籤選擇器（控制管理pod副本）；3、pod資源模板（如果pod數量少於期望的，就根據pod模板來新建一定數量的pod）。
Deployment控制器 ：Deployment透過控制replicaset來控制Pod。Deployment支援滾動更新和回滾，宣告式配置的功能。Deployment只關注群體，而不關注個體。
DaemonSet控制器
：用於確保叢集中的每一個節點只執行一個pod副本（畫外音，如果沒有DaemonSet，一個節點可以執行多個pod副本）。如果在叢集中新加一個節點，那麼這個新節點也會自動生成一個Pod副本。
Job控制器
：對於那些
只做一次，只要完成就正常退出，沒完成才重構pod
，叫job控制器。
StatefulSet控制器：
管理有狀態應用，每一個pod副本都是被單獨管理的。它擁有著自己獨有的標識。
K8s在1.2+和1.7開始，支援TPR(third party resources 第三方資源)。在k8s 1.8+中，支援CDR(Custom Defined Reources，使用者自定義資源)。
replicaset控制器
[root@master manifests]# kubectl explain replicaset [root@master manifests]# kubectl explain rs (replicaset的簡寫) [root@master manifests]# kubectl explain rs.spec.template
[root@master manifests]# kubectl get deploy NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE myapp 2 2 2 0 10d mytomcat 3 3 3 3 10d nginx-deploy 1 1 1 1 13d [root@master manifests]# kubectl delete deploy myapp deployment.extensions "myapp" deleted [root@master manifests]# kubectl delete deploy nginx-deploy deployment.extensions "nginx-deploy" deleted
[root@master manifests]# cat rs-demo.yaml apiVersion: apps/v1 kind: ReplicaSet metadata: name: myapp namespace: default spec: #這是控制器的spec replicas: 2 #幾個副本 selector: #檢視幫助:,標籤選擇器。 kubectl explain rs.spec.selector matchLabels: app: myapp release: canary template: # 檢視幫助：模板 kubectl explain rs.spec.template metadata: # kubectl explain rs.spec.template.metadata name: myapp-pod labels: #必須符合上面定義的標籤選擇器selector裡面的內容 app: myapp release: canary environment: qa spec: #這是pod的spec containers: - name: myapp-container image: ikubernetes/nginx:latest ports: - name: http containerPort: 80
[root@master manifests]# kubectl create -f rs-demo.yaml replicaset.apps/myapp created
[root@master manifests]# kubectl get rs NAME DESIRED CURRENT READY AGE myapp 2 2 2 3m
看到上面的ready是2，表示兩個replcatset控制器都在正常執行。
[root@master manifests]# kubectl get pods --show-labels myapp-6kncv 1/1 Running 0 15m app=myapp,environment=qa,release=canary myapp-rbqjz 1/1 Running 0 15m app=myapp,environment=qa,release=canary 5m pod-demo 0/2 CrashLoopBackOff 2552 9d app=myapp,tier=frontend
上面就是replicatset控制器建立的兩個pod。
[root@master manifests]# kubectl describe pods myapp-6kncv IP: 10.244.2.44
[root@master manifests]# curl 10.244.2.44 Hello MyApp | Version: v1 | <a href="hostname.html">Pod Name</a>
編輯replicatset的配置檔案（這個檔案不是我們手工建立的，而是apiserver維護的）
[root@master manifests]# kubectl edit rs myapp
把裡面的replicas改成5，儲存後就立即生效。
[root@master manifests]# kubectl get pods --show-labels NAME READY STATUS RESTARTS AGE LABELS client 0/1 Error 0 11d run=client liveness-httpget-pod 1/1 Running 3 5d <none> myapp-6kncv 1/1 Running 0 31m app=myapp,environment=qa,release=canary myapp-c64mb 1/1 Running 0 3s app=myapp,environment=qa,release=canary myapp-fsrsg 1/1 Running 0 3s app=myapp,environment=qa,release=canary myapp-ljczj 0/1 ContainerCreating 0 3s app=myapp,environment=qa,release=canary myapp-rbqjz 1/1 Running 0 31m app=myapp,environment=qa,release=canary
同樣，也可以用命令kubectl edit rs myapp升級版本，改裡面的image: ikubernetes/myapp:v2，這樣就變成v2版本了。
[root@master manifests]# kubectl get rs -o wide NAME DESIRED CURRENT READY AGE CONTAINERS IMAGES SELECTOR myapp 5 5 5 1h myapp-container ikubernetes/myapp:v2 app=myapp,release=canary
不過，只有pod重建後，比如增加刪除Pod，才會更新成v2版本。
Deployment控制器
我們可以透過Deployment控制器來動態更新pod的版本。
我們先建立replicatset v2版本，然後一個一個的刪除replicatset v1版本中的Pod，這樣自動新建立的pod就會變成v2版本了。當pod全部變成v2版本後，replicatset v1並不會刪除，這樣一旦發現v2版本有問題，還可以回退到v1版本。
通常deployment預設保留10版本的replicatset。
[root@master manifests]# kubectl explain deploy [root@master manifests]# kubectl explain deploy.spec [root@master manifests]# kubectl explain deploy.spec.strategy （更新策略） [root@master ~]# kubectl delete rs myapp
[root@master manifests]# cat deploy-demo.yaml apiVersion: apps/v1 kind: Deployment metadata: name: myapp-deploy namespace: default spec: replicas: 2 selector: #標籤選擇器 matchLabels: #匹配的標籤為 app: myapp release: canary template: metadata: labels: app: myapp #和上面的myapp要匹配 release: canary spec: containers: - name: myapp image: ikubernetes/myapp:v1 ports: - name: http containerPort: 80
[root@master manifests]# kubectl apply -f deploy-demo.yaml deployment.apps/myapp-deploy created
apply表示是宣告式更新和建立。
[root@master manifests]# kubectl get deploy NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE myapp-deploy 2 2 2 2 1m
[root@master ~]# kubectl get rs NAME DESIRED CURRENT READY AGE myapp-deploy-69b47bc96d 2 2 2 17m
上面的rs式deployment自動建立的。
[root@master ~]# kubectl get pods NAME READY STATUS RESTARTS AGE myapp-deploy-69b47bc96d-7jnwx 1/1 Running 0 19m myapp-deploy-69b47bc96d-btskk 1/1 Running 0 19m
修改配置檔案deploy-demo.yaml，把replicas數字改成3，然後再執行kubectl apply -f deploy-demo.yaml 即可使配置檔案裡面的內容生效。
[root@master ~]# kubectl describe deploy myapp-deploy
[root@master ~]# kubectl get pods -l app=myapp -w
-l使標籤過濾
-w是動態監控
[root@master ~]# kubectl get rs -o wide NAME DESIRED CURRENT READY AGE CONTAINERS IMAGES SELECTOR myapp-deploy-69b47bc96d 2 2 2 1h myapp ikubernetes/myapp:v1 app=myapp,pod-template-hash=2560367528,release=canary
看滾動更新的歷史：
[root@master ~]# kubectl rollout history deployment myapp-deploy deployments "myapp-deploy" REVISION CHANGE-CAUSE 1 <none>
下面我們把deployment改成5個：我們可以使用vim deploy-demo.yaml方法，把裡面的replicas改成5。當然，還可以使用另外一種方法，就patch方法，舉例如下。
[root@master manifests]# kubectl patch deployment myapp-deploy -p '{"spec":{"replicas":5}}'
deployment.extensions/myapp-deploy patched
[root@master manifests]# kubectl get deploy NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE myapp-deploy 5 5 5 5 2h
[root@master manifests]# kubectl get pods NAME READY STATUS RESTARTS AGE myapp-deploy-69b47bc96d-7jnwx 1/1 Running 0 2h myapp-deploy-69b47bc96d-8gn7v 1/1 Running 0 59s myapp-deploy-69b47bc96d-btskk 1/1 Running 0 2h myapp-deploy-69b47bc96d-p5hpd 1/1 Running 0 59s myapp-deploy-69b47bc96d-zjv4p 1/1 Running 0 59s mytomcat-5f8c6fdcb-9krxn 1/1 Running 0 8h
下面修改策略：
[root@master manifests]# kubectl patch deployment myapp-deploy -p '{"spec":{"strategy":{"rollingUpdate":{"maxSurge":1,"maxUnavaliable":0}}}}'
deployment.extensions/myapp-deploy patched
strategy：表示策略
maxSurge：表示最多幾個控制器存在
maxUnavaliable：表示最多有幾個控制器不可用
[root@master manifests]# kubectl describe deployment myapp-deploy RollingUpdateStrategy: 0 max unavailable, 1 max surge
下面我們用set image命令，將映象myapp升級為v3版本，並且將myapp-deploy控制器標記為暫停。被pause命令暫停的資源不會被控制器協調使用，可以使“kubectl rollout resume”命令恢復已暫停資源。
[root@master manifests]# kubectl set image deployment myapp-deploy myapp=ikubernetes/myapp:v3 && kubectl rollout pause deployment myapp-deploy
[root@master ~]# kubectl get pods -l app=myapp -w
停止暫停：
[root@master ~]# kubectl rollout resume deployment myapp-deploy deployment.extensions/myapp-deploy resumed
看到繼續更新了（即刪一個更新一個，刪一個更新一個）：
[root@master manifests]# kubectl rollout status deployment myapp-deploy Waiting for deployment "myapp-deploy" rollout to finish: 2 out of 5 new replicas have been updated... Waiting for deployment spec update to be observed... Waiting for deployment spec update to be observed... Waiting for deployment "myapp-deploy" rollout to finish: 2 out of 5 new replicas have been updated... Waiting for deployment "myapp-deploy" rollout to finish: 3 out of 5 new replicas have been updated... Waiting for deployment "myapp-deploy" rollout to finish: 3 out of 5 new replicas have been updated... Waiting for deployment "myapp-deploy" rollout to finish: 4 out of 5 new replicas have been updated... Waiting for deployment "myapp-deploy" rollout to finish: 4 out of 5 new replicas have been updated... Waiting for deployment "myapp-deploy" rollout to finish: 4 out of 5 new replicas have been updated... Waiting for deployment "myapp-deploy" rollout to finish: 1 old replicas are pending termination... Waiting for deployment "myapp-deploy" rollout to finish: 1 old replicas are pending termination... deployment "myapp-deploy" successfully rolled out
[root@master manifests]# kubectl get rs -o wide NAME DESIRED CURRENT READY AGE CONTAINERS IMAGES SELECTOR myapp-deploy-69b47bc96d 0 0 0 6h myapp ikubernetes/myapp:v1 app=myapp,pod-template-hash=2560367528,release=canary myapp-deploy-6bdcd6755d 5 5 5 3h myapp ikubernetes/myapp:v3 app=myapp,pod-template-hash=2687823118,release=canary mytomcat-5f8c6fdcb 3 3 3 12h mytomcat tomcat pod-template-hash=194729876,run=mytomcat
上面可以看到myapp有v1和v3兩個版本。
[root@master manifests]# kubectl rollout history deployment myapp-deploy deployments "myapp-deploy" REVISION CHANGE-CAUSE 1 <none> 2 <none>
上面可以看到有兩個歷史更新記錄。
下面我們把v3回退到上一個版本（不指定就是上一個版本）。
[root@master manifests]# kubectl rollout undo deployment myapp-deploy --to-revision=1 deployment.extensions/myapp-deploy
可以看到第一版還原成第3版了：
[root@master manifests]# kubectl rollout history deployment myapp-deploy deployments "myapp-deploy" REVISION CHANGE-CAUSE 2 <none> 3 <none>
可以看到正在工作的是v1版，即回退到了v1版。
[root@master manifests]# kubectl get rs -o wide NAME DESIRED CURRENT READY AGE CONTAINERS IMAGES SELECTOR myapp-deploy-69b47bc96d 5 5 5 6h myapp ikubernetes/myapp:v1 app=myapp,pod-template-hash=2560367528,release=canary myapp-deploy-6bdcd6755d 0 0 0 3h myapp ikubernetes/myapp:v3 app=myapp,pod-template-hash=2687823118,release=canary
DaemonSet控制器
透過
[root@node1 manifests]# docker pull ikubernetes/filebeat:5.6.5-alpine [root@node2 manifests]# docker pull ikubernetes/filebeat:5.6.5-alpine
node1和node2上都下載filebeat映象。
[root@node1 ~]# docker image inspect ikubernetes/filebeat:5.6.5-alpine
[root@master manifests]# kubectl explain pods.spec.containers.env
[root@master manifests]# cat ds-demo.yaml apiVersion: apps/v1 kind: DaemonSet metadata: name: myapp-ds namespace: default spec: selector: #標籤選擇器 matchLabels: #匹配的標籤為 app: filebeat release: stable template: metadata: labels: app: filebeat #和上面的myapp要匹配 release: stable spec: containers: - name: myapp image: ikubernetes/myapp:v1 env: - name: REDIS_HOST value: redis.default.svc.cluster.local #隨便取的名字 name: REDIS_LOG_LEVEL value: info
[root@master manifests]# kubectl apply -f ds-demo.yaml daemonset.apps/myapp-ds created
看到myapp-ds已經執行起來了，並且是兩個myapp-ds，這是因為我們有兩個Node節點。另外master節點上是不會執行myapp-ds控制器的，因為master有汙點（除非你設定允許有汙點，才可以在master上允許myapp-ds）
[root@master manifests]# kubectl get pods NAME READY STATUS RESTARTS AGE myapp-ds-5tmdd 1/1 Running 0 1m myapp-ds-dkmjj 1/1 Running 0 1m
[root@master ~]# kubectl logs myapp-ds-dkmjj
[root@master manifests]# kubectl delete -f ds-demo.yaml
[root@master manifests]# cat ds-demo.yaml apiVersion: apps/v1 kind: Deployment metadata: name: redis namespace: default spec: replicas: 1 selector: matchLabels: app: redis role: logstor #日誌儲存角色 template: metadata: labels: app: redis role: logstor spec: #這個是容器的spec containers: - name: redis image: redis:4.0-alpine ports: - name: redis containerPort: 6379 #用減號隔離資源定義清單 --- apiVersion: apps/v1 kind: DaemonSet metadata: name: filebeat-ds namespace: default spec: selector: #標籤選擇器 matchLabels: #匹配的標籤為 app: filebeat release: stable template: metadata: labels: app: filebeat #和上面的myapp要匹配 release: stable spec: containers: - name: filebeat image: ikubernetes/filebeat:5.6.6-alpine env: - name: REDIS_HOST #這是環境變數名,value是它的值 value: redis.default.svc.cluster.local #隨便取的名字 - name: REDIS_LOG_LEVEL value: info
[root@master manifests]# kubectl create -f ds-demo.yaml deployment.apps/redis created daemonset.apps/filebeat-ds created
[root@master manifests]# kubectl expose deployment redis --port=6379 ##這是在用expose方式建立service，其實還有一種方式是根據清單建立service service/redis exposed
[root@master manifests]# kubectl get svc #service的簡稱 NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE redis ClusterIP 10.106.138.181 <none> 6379/TCP 48s
[root@master manifests]# kubectl get pods NAME READY STATUS RESTARTS AGE filebeat-ds-hgbhr 1/1 Running 0 9h filebeat-ds-xc7v7 1/1 Running 0 9h redis-5b5d6fbbbd-khws2 1/1 Running 0 33m
[root@master manifests]# kubectl exec -it redis-5b5d6fbbbd-khws2 -- /bin/sh /data # netstat -tnl Active Internet connections (only servers) Proto Recv-Q Send-Q Local Address Foreign Address State tcp 0 0 0.0.0.0:6379 0.0.0.0:* LISTEN tcp 0 0 :::6379 :::* LISTEN /data # nslookup redis.default.svc.cluster.local #看到DNS可以解析出來ip nslookup: can't resolve '(null)': Name does not resolve Name: redis.default.svc.cluster.local Address 1: 10.106.138.181 redis.default.svc.cluster.local /data # redis-cli -h redis.default.svc.cluster.local redis.default.svc.cluster.local:6379> keys * (empty list or set) redis.default.svc.cluster.local:6379>
[root@master manifests]# kubectl exec -it filebeat-ds-pnk8b -- /bin/sh
/ # ps aux
PID USER TIME COMMAND
1 root 0:00 /usr/local/bin/filebeat -e -c /etc/filebeat/filebeat.yml
15 root 0:00 /bin/sh
22 root 0:00 ps aux
/ # cat /etc/filebeat/filebeat.yml
filebeat.registry_file: /var/log/containers/filebeat_registry
filebeat.idle_timeout: 5s
filebeat.spool_size: 2048
logging.level: info
filebeat.prospectors:
- input_type: log
paths:
- "/var/log/containers/*.log"
- "/var/log/docker/containers/*.log"
- "/var/log/startupscript.log"
- "/var/log/kubelet.log"
- "/var/log/kube-proxy.log"
- "/var/log/kube-apiserver.log"
- "/var/log/kube-controller-manager.log"
- "/var/log/kube-scheduler.log"
- "/var/log/rescheduler.log"
- "/var/log/glbc.log"
- "/var/log/cluster-autoscaler.log"
symlinks: true
json.message_key: log
json.keys_under_root: true
json.add_error_key: true
multiline.pattern: '^\s'
multiline.match: after
document_type: kube-logs
tail_files: true
fields_under_root: true
output.redis:
hosts: ${REDIS_HOST:?No Redis host configured. Use env var REDIS_HOST to set host.}
key: "filebeat"
/ # printenv
REDIS_HOST=redis.default.svc.cluster.local
/ # nslookup redis.default.svc.cluster.local
nslookup: can't resolve '(null)': Name does not resolve
Name: redis.default.svc.cluster.local
Address 1: 10.106.138.181 redis.default.svc.cluster.local
daemon-set也支援滾動更新。
[root@master manifests]# kubectl set image daemonsets filebeat-ds filebeat=ikubernetes/filebeat:5.5.7-alpine
說明： daemonsets filebeat-ds表示daemonsets名字叫filebeat-ds；
filebeat=ikubernetes/filebeat:5.5.7-alpine表示filebeat容器=ikubernetes/filebeat:5.5.7-alpine
來自 “ ITPUB部落格 ” ，連結：http://blog.itpub.net/28916011/viewspace-2214692/，如需轉載，請註明出處，否則將追究法律責任。
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