Kubernetes-8:Deployment、DaemonSet、Job、CronJob等各控制器介绍及演示
前文中也都已经提及过k8s都有哪些常用的控制器,本文对这些控制器进行细剖及演示一下
RS与RC与Deployment关联
RC主要作用就是用来确保容器应用副本数保持用户的期望值数目,即如果有pod异常退出,则会自动再创建Pod,同理会把多出来的Pod删除掉
Kubernetes官方建议使用RS来代替RC进行部署,RS跟RC没有本质的差别,只是名字不同,并且RS支持selector
vim rs.yaml ... apiVersion: extensions/v1beta1 kind: ReplicaSet metadata: name: frontend spec: replicas: 3 #副本数,对应下边的template selector: #选择(匹配)标签 matchLabels: tier: frontend #匹配标签为tier: frontend的Pod template: #模板 metadata: lables: #标签 tire: frontend spec: containers: - name: nginx image: hub.vfancloud.com/myapp/nginx:v1 env: - name: GET_HOSTS_FROM value: dns ports: - containerPort: 80 ... [root@Centos8 k8sYaml]# kubectl apply -f rs.yaml replicaset.extensions/frontend created [root@Centos8 k8sYaml]# kubectl get rs NAME DESIRED CURRENT READY AGE frontend 3 3 3 21s [root@Centos8 k8sYaml]# kubectl get pod NAME READY STATUS RESTARTS AGE frontend-6r2n9 1/1 Running 0 24s frontend-9vrvv 1/1 Running 0 24s frontend-vbt9c 1/1 Running 0 24s [root@Centos8 k8sYaml]# kubectl delete pod frontend-6r2n9 pod "frontend-6r2n9" deleted ## 维持了原本的副本数目 [root@Centos8 k8sYaml]# kubectl get pod NAME READY STATUS RESTARTS AGE frontend-9vrvv 1/1 Running 0 61s frontend-vbt9c 1/1 Running 0 61s frontend-zk7jn 1/1 Running 0 11s ## 删除RS,Pod也会随之删除 [root@Centos8 k8sYaml]# kubectl delete rs frontend replicaset.extensions "frontend" deleted [root@Centos8 k8sYaml]# kubectl get pod No resources found.
Deployment
Deployment 为 Pod 和 ReplicaSet 提供了一个声名式的定义(declarative)方法,用来代替以前的ReplicationController 来方便的管理应用,典型的应用场景包括:
- 定义Deployment来创建Pod和ReplicaSet
- 滚动升级和回滚应用
- 扩容和缩容
- 暂停和继续Delpoyment
资源清单
vim dm.yaml ... apiVersion: extensions/v1beta1 kind: Deployment metadata: name: nginx-deployment spec: relicas: 3 template: metadata: labels: app: nginx spec: containers: - name: nginx image: hub.vfancloud.com/myapp/nginx:v1 ports: - containerPort: 80 ... # --record 表示记录deployment Rollout的每一次变化 kubectl apply -f dm.yaml --record deployment.extensions/nginx-deployment created [root@Centos8 k8sYaml]# kubectl get deployment NAME READY UP-TO-DATE AVAILABLE AGE nginx-deployment 3/3 3 3 53s [root@Centos8 k8sYaml]# kubectl get pod NAME READY STATUS RESTARTS AGE nginx-deployment-66c8c6957b-bqxm6 1/1 Running 0 56s nginx-deployment-66c8c6957b-rdfxj 1/1 Running 0 56s nginx-deployment-66c8c6957b-tb8t4 1/1 Running 0 56s
扩容
# 将副本数扩充为7个 [root@Centos8 k8sYaml]# kubectl scale deployment/nginx-deployment --replicas=7 deployment.extensions/nginx-deployment scaled [root@Centos8 k8sYaml]# kubectl get pod NAME READY STATUS RESTARTS AGE nginx-deployment-66c8c6957b-6d4qf 1/1 Running 0 13s nginx-deployment-66c8c6957b-bqxm6 1/1 Running 0 2m48s nginx-deployment-66c8c6957b-pjz9h 1/1 Running 0 13s nginx-deployment-66c8c6957b-rdfxj 1/1 Running 0 2m48s nginx-deployment-66c8c6957b-shn7b 1/1 Running 0 13s nginx-deployment-66c8c6957b-tb8t4 1/1 Running 0 2m48s nginx-deployment-66c8c6957b-ttzhc 1/1 Running 0 13s
如果集群支持horizontal pod autoscaling设置自动扩展
# 根据cpu使用率来增加或减少模板数量 kubectl autoscale deployment nginx-deployment --min=10 --max=15 --cpu-percent=80
更新镜像也比较简单
# 将container name=nginx 的容器镜像修改为nginx:1.2.1 kubectl set image deployment nginx-deployment nginx=nginx:1.2.1 deployment.extensions/nginx-deployment image updated ## 滚动升级中... [root@Centos8 k8sYaml]# kubectl get pod NAME READY STATUS RESTARTS AGE nginx-deployment-54988485fb-5cfdd 0/1 ContainerCreating 0 9s nginx-deployment-54988485fb-rgmp2 0/1 ContainerCreating 0 9s nginx-deployment-66c8c6957b-6d4qf 1/1 Terminating 0 56m nginx-deployment-66c8c6957b-bqxm6 1/1 Running 0 59m nginx-deployment-66c8c6957b-pjz9h 1/1 Running 0 56m nginx-deployment-66c8c6957b-rdfxj 1/1 Running 0 59m nginx-deployment-66c8c6957b-shn7b 1/1 Running 0 56m nginx-deployment-66c8c6957b-tb8t4 1/1 Running 0 59m nginx-deployment-66c8c6957b-ttzhc 1/1 Running 0 56m ## 更新完毕 [root@Centos8 k8sYaml]# kubectl get pod NAME READY STATUS RESTARTS AGE nginx-deployment-54988485fb-2zksn 1/1 Running 0 100s nginx-deployment-54988485fb-5cfdd 1/1 Running 0 116s nginx-deployment-54988485fb-c6dpc 1/1 Running 0 106s nginx-deployment-54988485fb-rgmp2 1/1 Running 0 116s nginx-deployment-54988485fb-v24qq 1/1 Running 0 100s nginx-deployment-54988485fb-x6q56 1/1 Running 0 31s nginx-deployment-54988485fb-zxh27 1/1 Running 0 106s [root@Centos8 k8sYaml]# curl 10.244.3.56 <html> <head> <title>Welcome to nginx!</title> </head> <body bgcolor="white" text="black"> <center><h1>Welcome to nginx!</h1></center> </body> </html>
回滚
# 回滚为上一个nginx-deployment版本 [root@Centos8 k8sYaml]# kubectl rollout undo deployment nginx-deployment deployment.extensions/nginx-deployment rolled back ## 回滚中... [root@Centos8 k8sYaml]# kubectl get pod NAME READY STATUS RESTARTS AGE nginx-deployment-54988485fb-2zksn 1/1 Terminating 0 4m24s nginx-deployment-54988485fb-5cfdd 1/1 Running 0 4m40s nginx-deployment-54988485fb-c6dpc 1/1 Running 0 4m30s nginx-deployment-54988485fb-rgmp2 1/1 Running 0 4m40s nginx-deployment-54988485fb-v24qq 1/1 Terminating 0 4m24s nginx-deployment-54988485fb-x6q56 1/1 Terminating 0 3m15s nginx-deployment-54988485fb-zxh27 1/1 Running 0 4m30s nginx-deployment-66c8c6957b-dtsb6 0/1 ContainerCreating 0 1s nginx-deployment-66c8c6957b-f65gq 0/1 ContainerCreating 0 1s nginx-deployment-66c8c6957b-xj8j4 1/1 Running 0 5s nginx-deployment-66c8c6957b-xmstc 1/1 Running 0 5s
Deployment更新策略
# Deployment可以保证在升级时有一定的Pod必须处于UP状态,一般比整体副本数-1个处于UP状态,也就是一个Pod一个Pod的进行更新 # 未来的版本中,将从 1—>1 到 25%—>25% kubectl describe deployment
Rollover(多个Rollover并行)
假如创建了10个镜像为nginx:1.7.9replica的Deployment,开始创建到第3个时,你将镜像修改为了nginx:1.9.1版本,那么K8S会立刻删除之前旧镜像的3个Pod,开始创建新镜像的Pod
回退Deployment
只要Deployment的rollout被触发就会创建一个revision,也就是说当且仅当Deployment的template中内容被修改,例如更新template下的label和容器镜像,就会出现一个新的revision。其他操作,例如扩容Deployment不会触发Rollout
# 修改deployment的容器镜像 kubectl set image deployment nginx-deployment nginx=nginx:1.9.1 # 查看deployment下rollout的状态 kubectl rollout status deployment nginx-deployment # 查看当前pod 默认namespace为default kubectl get pod # 查看deployment所有的历史版本 kubectl rollout history deployment nginx-deployment # 回退为上一个版本的deployment kubectl rollout undo deployment nginx-deployment # 回退为指定版本的deployment --to-revision指定版本 kubectl rollout undo deployment nginx-deployment --to-revision=2 # 暂停deployment的更新 kubectl rollout pause deployment nginx-deployment
修改policy
可以通过设置spec.revisionHistoryLimit项来指定保留多少个revision历史记录,默认的会保留所有的revision,如果将该项设置为0,Deployment就不允许回退了
DaemonSet
DaemonSet确保全部(或者一些)Node上运行一个Pod副本、当有Node加入集群时,也会为他们新增一个Pod,当有Node从集群移除时,这些Pod也会被回收,删除DaemonSet将会删除它创建的所有Pod。
使用DaemonSet的一些典型用法
- 运行集群存储daemon,例如在每个Node上运行 glusterd、ceph
- 在每个Node节点运行日志收集damon,例如logstash、fluentd
- 在每个Node节点运行监控damon,例如Prometheus Node Exporter、collectd、Datadog代理、New Relic代理等
apiVersion: apps/v1
kind: DaemonSet
metadata:
name: daemonset-example
labels:
app: daemonset
spec:
selector:
matchLabels:
name: daemonset-example
template:
metadata:
name: daemonset-example
labels: daemonset
spec:
containers:
- name: deamonset-example
image: hub.vfancloud.com/myapp:v1
Job
Job负责批处理任务,即仅执行一次的任务,它保证批处理任务的一个或多个Pod成功结束
特殊说明
- spec.template格式同Pod
- RestartPolicy仅支持Never或OnFailure
- 单个Pod时,默认Pod成功运行后Job即结束
- .spec.completions标志Job结束需要成功运行的Pod个数,默认为1
- .spec.parallelism标志并行运行的Pod的个数,默认为1
- .spec.activeDeadlineSeconds 标志失败Pod重试的最大时间,超过这个时间不会继续重试
Example
vim job.yaml ... apiVersion: batch/v1 kind: Job metadata: name: p1 spec: template: metadata: labels: type: job name: p1 spec: containers: - name: p1 image: perl:v1 command: ["perl","-Mbignum=bpi","-wle","print bpi(2000)"] #圆周率后2000位 imagePullPolicy: IfNotPresent restartPolicy: Never ... [root@Centos8 k8sYaml]# kubectl create -f job.yaml job.batch/p1 created [root@Centos8 k8sYaml]# kubectl get pod NAME READY STATUS RESTARTS AGE p1-49lcs 1/1 Running 0 6s [root@Centos8 k8sYaml]# kubectl get job NAME COMPLETIONS DURATION AGE p1 1/1 14s 21s ## 圆周率小数点后2000位 [root@Centos8 k8sYaml]# kubectl logs p1-49lcs 3.1415926535897932384626433832795028841971693993751058209749445923078164062862089986280348253421170679821480865132823066470938446095505822317253594081284811174502841027019385211055596446229489549303819644288109756659334461284756482337867831652712019091456485669234603486104543266482133936072602491412737245870066063155881748815209209628292540917153643678925903600113305305488204665213841469519415116094330572703657595919530921861173819326117931051185480744623799627495673518857527248912279381830119491298336733624406566430860213949463952247371907021798609437027705392171762931767523846748184676694051320005681271452635608277857713427577896091736371787214684409012249534301465495853710507922796892589235420199561121290219608640344181598136297747713099605187072113499999983729780499510597317328160963185950244594553469083026425223082533446850352619311881710100031378387528865875332083814206171776691473035982534904287554687311595628638823537875937519577818577805321712268066130019278766111959092164201989380952572010654858632788659361533818279682303019520353018529689957736225994138912497217752834791315155748572424541506959508295331168617278558890750983817546374649393192550604009277016711390098488240128583616035637076601047101819429555961989467678374494482553797747268471040475346462080466842590694912933136770289891521047521620569660240580381501935112533824300355876402474964732639141992726042699227967823547816360093417216412199245863150302861829745557067498385054945885869269956909272107975093029553211653449872027559602364806654991198818347977535663698074265425278625518184175746728909777727938000816470600161452491921732172147723501414419735685481613611573525521334757418494684385233239073941433345477624168625189835694855620992192221842725502542568876717904946016534668049886272327917860857843838279679766814541009538837863609506800642251252051173929848960841284886269456042419652850222106611863067442786220391949450471237137869609563643719172874677646575739624138908658326459958133904780275898
CronJob
CronJob执行会自动创建Job,然后Job再创建Pod,最后再执行任务,其模式就跟创建Deployment会自动创建ReplicaSet再生成Pod一致。
- .spec.schedule指定任务运行周期,格式同Cron
- .spec.jobTemplate指定需要运行的任务,格式同Job
- .spec.startingDeadineSeconds指定任务开始的截止期限
- .spec.concurrencyPolicy指定任务的并发策略,支持Allow、Forbid和Replace三个选项
vim cronjob.yaml ... apiVersion: batch/v1beta1 kind: CronJob metadata: name: hello spec: schedule: "*/1 * * * *" jobTemplate: spec: template: spec: containers: - name: hello image: busybox:v1 command: ["/bin/sh","-c","date;echo Welcome here"] imagePullPolicy: IfNotPresent restartPolicy: OnFailure ... [root@Centos8 k8sYaml]# kubectl create -f cronjob.yaml cronjob.batch/hello created [root@Centos8 k8sYaml]# kubectl get cronjob NAME SCHEDULE SUSPEND ACTIVE LAST SCHEDULE AGE hello */1 * * * * False 0 <none> 24s [root@Centos8 k8sYaml]# kubectl get pod NAME READY STATUS RESTARTS AGE hello-1589101500-shzd6 0/1 Completed 0 2m9s hello-1589101560-ddrp7 0/1 Completed 0 69s hello-1589101620-vmwfg 0/1 Completed 0 9s ## 可以看到,命令每1分钟执行一次 [root@Centos8 k8sYaml]# kubectl log hello-1589101500-shzd6 log is DEPRECATED and will be removed in a future version. Use logs instead. Sun May 10 09:05:02 UTC 2020 Welcome here [root@Centos8 k8sYaml]# kubectl log hello-1589101560-ddrp7 log is DEPRECATED and will be removed in a future version. Use logs instead. Sun May 10 09:06:02 UTC 2020 Welcome here