容器编排系统k8s之DaemonSet、Job和CronJob控制器
DaemonSet控制器的主要作用是管理守护进程类的Pod，通常用于在每个节点需要运行一个这样的Pod场景；比如我们要收集日志到es中，我们就可以使用这种控制器在每个节点上运行一个Pod；DaemonSet控制器和Deployment控制器很类似，不同的是ds(DaemonSet的简写)控制器不需要我们手动指定其运行的pod数量，它会根据k8s集群节点数量的变化而变化，如果新加入一个节点它会自动扩展对应pod数量，减少节点时，它也不会把之前运行在该节点上的pod调度到其他节点，总之一个节点上只能运行同类型Pod1个；除此之外ds它还支持通过节点选择器来做选择性的调度；比如，在某个拥有对应标签的节点就运行对应pod，没有就不运行；其他的更新操作和deployment差不多；
前文我们了解了k8s上的pod控制器中的常用的两种控制器ReplicaSet和Deployment控制器的相关话题，回顾请参考：https://www.cnblogs.com/qiuhom-1874/p/14149042.html；今天我们来了解下DaemonSet、Job和CronJob控制器相关话题；
1、DaemonSet控制器
从名字上就可以看出这个控制器是管理守护进程类的pod；DaemonSet控制器的主要作用是管理守护进程类的Pod，通常用于在每个节点需要运行一个这样的Pod场景；比如我们要收集日志到es中，我们就可以使用这种控制器在每个节点上运行一个Pod；DaemonSet控制器和Deployment控制器很类似，不同的是ds(DaemonSet的简写)控制器不需要我们手动指定其运行的pod数量，它会根据k8s集群节点数量的变化而变化，如果新加入一个节点它会自动扩展对应pod数量，减少节点时，它也不会把之前运行在该节点上的pod调度到其他节点，总之一个节点上只能运行同类型Pod1个；除此之外ds它还支持通过节点选择器来做选择性的调度；比如，在某个拥有对应标签的节点就运行对应pod，没有就不运行；其他的更新操作和deployment差不多；
示例：创建DaemonSet控制器
[root@master01 ~]# cat ds-demo-nginx-1.14.yaml
apiVersion: apps/v1
kind: DaemonSet
metadata:
name: ds-demo
namespace: default
spec:
selector:
matchLabels:
app: ngx-ds
template:
metadata:
labels:
app: ngx-ds
spec:
containers:
- name: nginx
image: nginx:1.14-alpine
ports:
- name: http
containerPort: 80
minReadySeconds: 5
[root@master01 ~]#
提示：对于ds控制器来说，它在spec中最主要定义选择器和pod模板，这个定义和deploy控制器一样；上述配置文件主要使用ds控制器运行一个nginx pod，其标签名为ngx-ds；
应用配置清单
[root@master01 ~]# kubectl apply -f ds-demo-nginx-1.14.yaml daemonset.apps/ds-demo created [root@master01 ~]# kubectl get ds -o wide NAME DESIRED CURRENT READY UP-TO-DATE AVAILABLE NODE SELECTOR AGE CONTAINERS IMAGES SELECTOR ds-demo 3 3 3 3 3 <none> 14s nginx nginx:1.14-alpine app=ngx-ds
提示：可以看到我们并没有指定pod数量，对应控制器它会根据节点数量在每个node节点上创建pod；
验证：查看pod情况，看看是不是每个节点都被调度运行了一个pod?
[root@master01 ~]# kubectl get pod -o wide NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES ds-demo-fm9cb 1/1 Running 0 27s 10.244.1.57 node01.k8s.org <none> <none> ds-demo-pspbk 1/1 Running 0 27s 10.244.3.57 node03.k8s.org <none> <none> ds-demo-zvpbb 1/1 Running 0 27s 10.244.2.69 node02.k8s.org <none> <none> [root@master01 ~]#
提示：可以看到对应pod在每个node节点都仅跑了一个pod；
定义节点选择器
[root@master01 ~]# cat ds-demo-nginx-1.14.yaml
apiVersion: apps/v1
kind: DaemonSet
metadata:
name: ds-demo
namespace: default
spec:
selector:
matchLabels:
app: ngx-ds
template:
metadata:
labels:
app: ngx-ds
spec:
containers:
- name: nginx
image: nginx:1.14-alpine
ports:
- name: http
containerPort: 80
nodeSelector:
app: nginx-1.14-alpine
minReadySeconds: 5
[root@master01 ~]#
提示：定义节点选择器需要在pod模板中的spec字段下使用nodeSelector字段来定义，这个字段的值为一个字典；以上配置定义了只有节点标签为app=nginx-1.14-alpine才会在对应节点上创建pod，否则就不予创建；
应用配置清单
[root@master01 ~]# kubectl get ds NAME DESIRED CURRENT READY UP-TO-DATE AVAILABLE NODE SELECTOR AGE ds-demo 3 3 3 3 3 <none> 14m [root@master01 ~]# kubectl apply -f ds-demo-nginx-1.14.yaml daemonset.apps/ds-demo configured [root@master01 ~]# kubectl get ds NAME DESIRED CURRENT READY UP-TO-DATE AVAILABLE NODE SELECTOR AGE ds-demo 0 0 0 0 0 app=nginx-1.14-alpine 14m [root@master01 ~]# kubectl get pod NAME READY STATUS RESTARTS AGE ds-demo-pspbk 0/1 Terminating 0 14m [root@master01 ~]# kubectl get pod No resources found in default namespace. [root@master01 ~]#
提示：可以看到加上了节点选择器以后，对应pod都被删除了，原因是在k8s节点上没有任何一个节点拥有对应节点选择器中的标签，所以都不满足调度条件，当然对应pod就被控制器删除了；
测试：给node01.k8s.org节点添加一个节点标签，其名为app=nginx-1.14-alpine，看看对应节点是否会创建pod？
[root@master01 ~]# kubectl label node node01.k8s.org app=nginx-1.14-alpine node/node01.k8s.org labeled [root@master01 ~]# kubectl get ds -o wide NAME DESIRED CURRENT READY UP-TO-DATE AVAILABLE NODE SELECTOR AGE CONTAINERS IMAGES SELECTOR ds-demo 1 1 1 1 1 app=nginx-1.14-alpine 20m nginx nginx:1.14-alpine app=ngx-ds [root@master01 ~]# kubectl get pod -o wide NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES ds-demo-8hfnq 1/1 Running 0 18s 10.244.1.58 node01.k8s.org <none> <none> [root@master01 ~]#
提示：可以看到只要k8snode节点拥有对应node选择器匹配的标签时，对应pod就会精准调度到对应节点上运行；
删除节点选择器，应用资源配置清单，然后再新加一个节点，看看新加的节点是否会自动创建对应pod?
删除节点选择器，应用资源配置清单
[root@master01 ~]# cat ds-demo-nginx-1.14.yaml
apiVersion: apps/v1
kind: DaemonSet
metadata:
name: ds-demo
namespace: default
spec:
selector:
matchLabels:
app: ngx-ds
template:
metadata:
labels:
app: ngx-ds
spec:
containers:
- name: nginx
image: nginx:1.14-alpine
ports:
- name: http
containerPort: 80
minReadySeconds: 5
[root@master01 ~]# kubectl apply -f ds-demo-nginx-1.14.yaml
daemonset.apps/ds-demo configured
[root@master01 ~]# kubectl get ds -o wide
NAME DESIRED CURRENT READY UP-TO-DATE AVAILABLE NODE SELECTOR AGE CONTAINERS IMAGES SELECTOR
ds-demo 3 3 3 3 3 <none> 26m nginx nginx:1.14-alpine app=ngx-ds
[root@master01 ~]#
准备一台node节点，其主机名为node04.k8s.org，准备步骤请参考https://www.cnblogs.com/qiuhom-1874/p/14126750.html；
在master节点上创建节点加入集群的命令
[root@master01 ~]# kubeadm token create --print-join-command kubeadm join 192.168.0.41:6443 --token 8rdaut.qeeyf9cw5e1dur8f --discovery-token-ca-cert-hash sha256:330db1e5abff4d0e62150596f3e989cde40e61bdc73d6477170d786fcc1cfc67 [root@master01 ~]#
复制命令在node04上执行
[root@node04 ~]# kubeadm join 192.168.0.41:6443 --token 8rdaut.qeeyf9cw5e1dur8f --discovery-token-ca-cert-hash sha256:330db1e5abff4d0e62150596f3e989cde40e61bdc73d6477170d786fcc1cfc67 --ignore-preflight-errors=Swap
[preflight] Running pre-flight checks
[WARNING IsDockerSystemdCheck]: detected "cgroupfs" as the Docker cgroup driver. The recommended driver is "systemd". Please follow the guide at https://kubernetes.io/docs/setup/cri/
[WARNING Swap]: running with swap on is not supported. Please disable swap
[WARNING SystemVerification]: this Docker version is not on the list of validated versions: 20.10.1. Latest validated version: 19.03
[WARNING Service-Kubelet]: kubelet service is not enabled, please run 'systemctl enable kubelet.service'
[preflight] Reading configuration from the cluster...
[preflight] FYI: You can look at this config file with 'kubectl -n kube-system get cm kubeadm-config -o yaml'
[kubelet-start] Writing kubelet configuration to file "/var/lib/kubelet/config.yaml"
[kubelet-start] Writing kubelet environment file with flags to file "/var/lib/kubelet/kubeadm-flags.env"
[kubelet-start] Starting the kubelet
[kubelet-start] Waiting for the kubelet to perform the TLS Bootstrap...
This node has joined the cluster:
* Certificate signing request was sent to apiserver and a response was received.
* The Kubelet was informed of the new secure connection details.
Run 'kubectl get nodes' on the control-plane to see this node join the cluster.
[root@node04 ~]#
提示：如果开启了Swap，需要在命令后面加上--ignore-preflight-errors=Swap选项；
在master节点上查看node状态，看看node04是否加入到k8s集群
[root@master01 ~]# kubectl get node NAME STATUS ROLES AGE VERSION master01.k8s.org Ready control-plane,master 10d v1.20.0 node01.k8s.org Ready <none> 10d v1.20.0 node02.k8s.org Ready <none> 10d v1.20.0 node03.k8s.org Ready <none> 10d v1.20.0 node04.k8s.org NotReady <none> 117s v1.20.0 [root@master01 ~]#
提示：能够看到node04已经加入节点，只是状态还未准备好，待节点准备就绪后，再看看dspod数量是否增加，是否自动在node04上运行了nginx pod；
查看ds控制器，看看现在运行了几个pod
[root@master01 ~]# kubectl get node NAME STATUS ROLES AGE VERSION master01.k8s.org Ready control-plane,master 10d v1.20.0 node01.k8s.org Ready <none> 10d v1.20.0 node02.k8s.org Ready <none> 10d v1.20.0 node03.k8s.org Ready <none> 10d v1.20.0 node04.k8s.org Ready <none> 8m10s v1.20.0 [root@master01 ~]# kubectl get ds NAME DESIRED CURRENT READY UP-TO-DATE AVAILABLE NODE SELECTOR AGE ds-demo 4 4 4 4 4 <none> 53m [root@master01 ~]# kubectl get pod -o wide NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES ds-demo-g74s8 1/1 Running 0 72s 10.244.4.2 node04.k8s.org <none> <none> ds-demo-h4b77 1/1 Running 0 27m 10.244.2.70 node02.k8s.org <none> <none> ds-demo-hpmrg 1/1 Running 0 27m 10.244.3.58 node03.k8s.org <none> <none> ds-demo-kjf6f 1/1 Running 0 27m 10.244.1.59 node01.k8s.org <none> <none> [root@master01 ~]#
提示：可以看到新加的节点准备就绪以后，对应pod会自动在新加的节点上创建pod；
更新pod版本
[root@master01 ~]# cat ds-demo-nginx-1.14.yaml
apiVersion: apps/v1
kind: DaemonSet
metadata:
name: ds-demo
namespace: default
spec:
selector:
matchLabels:
app: ngx-ds
template:
metadata:
labels:
app: ngx-ds
spec:
containers:
- name: nginx
image: nginx:1.16-alpine
ports:
- name: http
containerPort: 80
minReadySeconds: 5
[root@master01 ~]# kubectl get ds -o wide
NAME DESIRED CURRENT READY UP-TO-DATE AVAILABLE NODE SELECTOR AGE CONTAINERS IMAGES SELECTOR
ds-demo 4 4 4 4 4 <none> 55m nginx nginx:1.14-alpine app=ngx-ds
[root@master01 ~]# kubectl get pod -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
ds-demo-g74s8 1/1 Running 0 3m31s 10.244.4.2 node04.k8s.org <none> <none>
ds-demo-h4b77 1/1 Running 0 30m 10.244.2.70 node02.k8s.org <none> <none>
ds-demo-hpmrg 1/1 Running 0 30m 10.244.3.58 node03.k8s.org <none> <none>
ds-demo-kjf6f 1/1 Running 0 30m 10.244.1.59 node01.k8s.org <none> <none>
[root@master01 ~]# kubectl apply -f ds-demo-nginx-1.14.yaml
daemonset.apps/ds-demo configured
[root@master01 ~]# kubectl get ds -o wide
NAME DESIRED CURRENT READY UP-TO-DATE AVAILABLE NODE SELECTOR AGE CONTAINERS IMAGES SELECTOR
ds-demo 4 4 3 0 3 <none> 56m nginx nginx:1.16-alpine app=ngx-ds
[root@master01 ~]#kubectl get pod -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
ds-demo-47gtq 0/1 ContainerCreating 0 7s <none> node04.k8s.org <none> <none>
ds-demo-h4b77 1/1 Running 0 31m 10.244.2.70 node02.k8s.org <none> <none>
ds-demo-jp9dz 1/1 Running 0 38s 10.244.1.60 node01.k8s.org <none> <none>
ds-demo-t4njt 1/1 Running 0 21s 10.244.3.59 node03.k8s.org <none> <none>
[root@master01 ~]# kubectl get pod -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
ds-demo-47gtq 1/1 Running 0 37s 10.244.4.3 node04.k8s.org <none> <none>
ds-demo-8txr9 1/1 Running 0 14s 10.244.2.71 node02.k8s.org <none> <none>
ds-demo-jp9dz 1/1 Running 0 68s 10.244.1.60 node01.k8s.org <none> <none>
ds-demo-t4njt 1/1 Running 0 51s 10.244.3.59 node03.k8s.org <none> <none>
[root@master01 ~]#
提示：可以看到我们修改了pod模板中镜像的版本，应用以后，对应pod会一一更新；
查看ds详细信息
[root@master01 ~]# kubectl describe ds ds-demo
Name: ds-demo
Selector: app=ngx-ds
Node-Selector: <none>
Labels: <none>
Annotations: deprecated.daemonset.template.generation: 4
Desired Number of Nodes Scheduled: 4
Current Number of Nodes Scheduled: 4
Number of Nodes Scheduled with Up-to-date Pods: 4
Number of Nodes Scheduled with Available Pods: 4
Number of Nodes Misscheduled: 0
Pods Status: 4 Running / 0 Waiting / 0 Succeeded / 0 Failed
Pod Template:
Labels: app=ngx-ds
Containers:
nginx:
Image: nginx:1.16-alpine
Port: 80/TCP
Host Port: 0/TCP
Environment: <none>
Mounts: <none>
Volumes: <none>
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal SuccessfulCreate 59m daemonset-controller Created pod: ds-demo-fm9cb
Normal SuccessfulCreate 59m daemonset-controller Created pod: ds-demo-zvpbb
Normal SuccessfulCreate 59m daemonset-controller Created pod: ds-demo-pspbk
Normal SuccessfulDelete 44m (x2 over 44m) daemonset-controller Deleted pod: ds-demo-fm9cb
Normal SuccessfulDelete 44m (x2 over 44m) daemonset-controller Deleted pod: ds-demo-pspbk
Normal SuccessfulDelete 44m (x2 over 44m) daemonset-controller Deleted pod: ds-demo-zvpbb
Normal SuccessfulCreate 38m daemonset-controller Created pod: ds-demo-8hfnq
Normal SuccessfulCreate 33m daemonset-controller Created pod: ds-demo-h4b77
Normal SuccessfulCreate 33m daemonset-controller Created pod: ds-demo-hpmrg
Normal SuccessfulDelete 33m daemonset-controller Deleted pod: ds-demo-8hfnq
Normal SuccessfulCreate 33m daemonset-controller Created pod: ds-demo-kjf6f
Normal SuccessfulCreate 6m57s daemonset-controller Created pod: ds-demo-g74s8
Normal SuccessfulDelete 3m8s daemonset-controller Deleted pod: ds-demo-kjf6f
Normal SuccessfulCreate 2m58s daemonset-controller Created pod: ds-demo-jp9dz
Normal SuccessfulDelete 2m52s daemonset-controller Deleted pod: ds-demo-hpmrg
Normal SuccessfulCreate 2m41s daemonset-controller Created pod: ds-demo-t4njt
Normal SuccessfulDelete 2m35s daemonset-controller Deleted pod: ds-demo-g74s8
Normal SuccessfulCreate 2m27s daemonset-controller Created pod: ds-demo-47gtq
Normal SuccessfulDelete 2m13s daemonset-controller Deleted pod: ds-demo-h4b77
Normal SuccessfulCreate 2m4s daemonset-controller Created pod: ds-demo-8txr9
[root@master01 ~]#
使用命令更新pod版本
[root@master01 ~]# kubectl set image ds ds-demo nginx=nginx:1.18-alpine --record
daemonset.apps/ds-demo image updated
[root@master01 ~]# kubectl get ds -o wide
NAME DESIRED CURRENT READY UP-TO-DATE AVAILABLE NODE SELECTOR AGE CONTAINERS IMAGES SELECTOR
ds-demo 4 4 3 0 3 <none> 84m nginx nginx:1.18-alpine app=ngx-ds
[root@master01 ~]# kubectl rollout status ds/ds-demo
Waiting for daemon set "ds-demo" rollout to finish: 1 out of 4 new pods have been updated...
Waiting for daemon set "ds-demo" rollout to finish: 2 out of 4 new pods have been updated...
Waiting for daemon set "ds-demo" rollout to finish: 2 out of 4 new pods have been updated...
Waiting for daemon set "ds-demo" rollout to finish: 2 out of 4 new pods have been updated...
Waiting for daemon set "ds-demo" rollout to finish: 2 out of 4 new pods have been updated...
Waiting for daemon set "ds-demo" rollout to finish: 3 out of 4 new pods have been updated...
Waiting for daemon set "ds-demo" rollout to finish: 3 out of 4 new pods have been updated...
Waiting for daemon set "ds-demo" rollout to finish: 3 out of 4 new pods have been updated...
Waiting for daemon set "ds-demo" rollout to finish: 3 out of 4 new pods have been updated...
Waiting for daemon set "ds-demo" rollout to finish: 3 of 4 updated pods are available...
Waiting for daemon set "ds-demo" rollout to finish: 3 of 4 updated pods are available...
daemon set "ds-demo" successfully rolled out
[root@master01 ~]# kubectl get pod -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
ds-demo-6qr6g 1/1 Running 0 70s 10.244.2.77 node02.k8s.org <none> <none>
ds-demo-7gnxd 1/1 Running 0 57s 10.244.3.66 node03.k8s.org <none> <none>
ds-demo-g44bd 1/1 Running 0 24s 10.244.1.66 node01.k8s.org <none> <none>
ds-demo-hb8vl 1/1 Running 0 43s 10.244.4.10 node04.k8s.org <none> <none>
[root@master01 ~]# kubectl describe pod/ds-demo-6qr6g |grep Image
Image: nginx:1.18-alpine
Image ID: docker-pullable://nginx@sha256:a7bdf9e789a40bf112c87672a2495fc49de7c89f184a252d59061c1ae800ee52
[root@master01 ~]#
提示：默认更新策略是删除一个pod，然后再新建一个pod；
定义更新策略
[root@master01 ~]# cat ds-demo-nginx-1.14.yaml
apiVersion: apps/v1
kind: DaemonSet
metadata:
name: ds-demo
namespace: default
spec:
selector:
matchLabels:
app: ngx-ds
template:
metadata:
labels:
app: ngx-ds
spec:
containers:
- name: nginx
image: nginx:1.16-alpine
ports:
- name: http
containerPort: 80
minReadySeconds: 5
updateStrategy:
type: RollingUpdate
rollingUpdate:
maxUnavailable: 2
[root@master01 ~]#
提示：定义ds的更新策略需要在spec字段下使用updateStrategy字段，该字段的值为一个对象，其中type是更新类型，该类型有两个值，一个是OnDelete，一个是RollingUpdate；rollingUpdate字段用于指定更新策略，只有当type的值为RollingUpdate时，定义rollingUpdate字段才有意义，其中maxUnavaiable是用来定义一次删除几个pod（最大允许不可用的pod数量）；ds更新只能先删除再创建，不能先创建再删除，因为它只允许一个node上运行一个pod，所以只有删除pod后再创建；默认情况是删除一个，新建一个；上述配置定义更新策略为一次删除两个；
应用配置，查看更新过程
[root@master01 ~]# kubectl apply -f ds-demo-nginx-1.14.yaml && kubectl get pod -w daemonset.apps/ds-demo configured NAME READY STATUS RESTARTS AGE ds-demo-4k2x7 1/1 Terminating 0 15m ds-demo-b9djn 1/1 Running 0 16m ds-demo-bxkj7 1/1 Running 0 15m ds-demo-cg49r 1/1 Terminating 0 16m ds-demo-cg49r 0/1 Terminating 0 16m ds-demo-4k2x7 0/1 Terminating 0 15m ds-demo-cg49r 0/1 Terminating 0 16m ds-demo-cg49r 0/1 Terminating 0 16m ds-demo-dtsgc 0/1 Pending 0 0s ds-demo-dtsgc 0/1 Pending 0 0s ds-demo-dtsgc 0/1 ContainerCreating 0 0s ds-demo-dtsgc 1/1 Running 0 2s ds-demo-4k2x7 0/1 Terminating 0 15m ds-demo-4k2x7 0/1 Terminating 0 15m ds-demo-8d7g9 0/1 Pending 0 0s ds-demo-8d7g9 0/1 Pending 0 0s ds-demo-8d7g9 0/1 ContainerCreating 0 0s ds-demo-8d7g9 1/1 Running 0 1s ds-demo-b9djn 1/1 Terminating 0 16m ds-demo-b9djn 0/1 Terminating 0 16m ds-demo-bxkj7 1/1 Terminating 0 16m ds-demo-bxkj7 0/1 Terminating 0 16m ds-demo-b9djn 0/1 Terminating 0 16m ds-demo-b9djn 0/1 Terminating 0 16m ds-demo-dkxfs 0/1 Pending 0 0s ds-demo-dkxfs 0/1 Pending 0 0s ds-demo-dkxfs 0/1 ContainerCreating 0 0s ds-demo-dkxfs 1/1 Running 0 2s ds-demo-bxkj7 0/1 Terminating 0 16m ds-demo-bxkj7 0/1 Terminating 0 16m ds-demo-q6b5f 0/1 Pending 0 0s ds-demo-q6b5f 0/1 Pending 0 0s ds-demo-q6b5f 0/1 ContainerCreating 0 0s ds-demo-q6b5f 1/1 Running 0 1s
提示：可以看到现在更新pod版本就是一次删除两个pod，然后新建两个pod；
2、Job控制器
job控制器主要作用是用来运行一个或多个pod来执行任务，当任务执行完成后，自动退出，如果在执行任务过程中pod故障了，job控制器会根据重启策略将其进行重启，直到任务完成pod正常退出；如果重启策略为Never，则pod异常后将不再重启，它会重新创建一个新pod再次执行任务，最后直到任务完成正常退出；
Job控制器pod状态
提示：上图主要描述了对于job控制器创建的pod的状态，正常情况pod执行完任务正常退出，其状态为completed；如果pod非正常退出（即退出码非0），并且重启策略为never，表示不重启pod，此时pod的状态就为Failure：虽然不重启pod，但是对应的任务还是在，所以重启策略为never时，pod非正常退出，job控制器会重新创建一个pod再次执行任务；如果pod非正常退出且重启策略为OnFailure时，pod会被重启，然后再次执行任务，直到最后任务执行完成pod正常退出，此时pod的状态为completed;
任务作业方式
串行作业
提示：串行作业一次只有一个pod被创建，只有当pod任务执行完成后，第二个pod才会被创建；
并行作业
提示：并行作业可以并行启动多个pod同时作业；
示例：定义job控制器
[root@master01 ~]# cat job-demo.yaml
apiVersion: batch/v1
kind: Job
metadata:
name: job-demo
spec:
template:
metadata:
labels:
app: myjob
spec:
containers:
- name: myjob
image: alpine
command: ["/bin/sh", "-c", "sleep 10"]
restartPolicy: Never
[root@master01 ~]#
提示：创建job控制最主要是定义对应pod模板；定义方式和pod其他控制器定义方式相同；在spec字段下使用template指定来定义pod模板；
应用配置清单
[root@master01 ~]# kubectl apply -f job-demo.yaml job.batch/job-demo created [root@master01 ~]# kubectl get jobs -o wide NAME COMPLETIONS DURATION AGE CONTAINERS IMAGES SELECTOR job-demo 0/1 7s 7s myjob alpine controller-uid=4ded17a8-fc39-480e-8f37-6bb2bd328997 [root@master01 ~]# kubectl get pod NAME READY STATUS RESTARTS AGE ds-demo-8d7g9 1/1 Running 0 91m ds-demo-dkxfs 1/1 Running 0 91m ds-demo-dtsgc 1/1 Running 0 91m ds-demo-q6b5f 1/1 Running 0 91m job-demo-4h9gb 1/1 Running 0 16s [root@master01 ~]# kubectl get pod NAME READY STATUS RESTARTS AGE ds-demo-8d7g9 1/1 Running 0 91m ds-demo-dkxfs 1/1 Running 0 91m ds-demo-dtsgc 1/1 Running 0 91m ds-demo-q6b5f 1/1 Running 0 91m job-demo-4h9gb 0/1 Completed 0 30s [root@master01 ~]#
提示：可以看到创建job控制后，对应启动pod执行完任务后就正常退出，此时pod的状态为completed；
定义并行job控制器
[root@master01 ~]# cat job-multi.yaml
apiVersion: batch/v1
kind: Job
metadata:
name: job-multi-demo
spec:
completions: 6
template:
metadata:
labels:
app: myjob
spec:
containers:
- name: myjob
image: alpine
command: ["/bin/sh", "-c", "sleep 10"]
restartPolicy: Never
[root@master01 ~]#
提示：定义多路并行pod需要在spec字段下使用completions来指定执行任务需要的对应pod的数量；以上配置表示job-multi-demo这个job控制器执行任务需要启动6个pod；
应用配置清单
[root@master01 ~]# kubectl apply -f job-multi.yaml job.batch/job-multi-demo created [root@master01 ~]# kubectl get jobs -o wide NAME COMPLETIONS DURATION AGE CONTAINERS IMAGES SELECTOR job-demo 1/1 18s 9m49s myjob alpine controller-uid=4ded17a8-fc39-480e-8f37-6bb2bd328997 job-multi-demo 0/6 6s 6s myjob alpine controller-uid=80f44cbd-f7e5-4eb4-a286-39bfcfc9fe39 [root@master01 ~]# kubectl get pods -o wide NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES ds-demo-8d7g9 1/1 Running 0 101m 10.244.3.69 node03.k8s.org <none> <none> ds-demo-dkxfs 1/1 Running 0 101m 10.244.1.69 node01.k8s.org <none> <none> ds-demo-dtsgc 1/1 Running 0 101m 10.244.4.13 node04.k8s.org <none> <none> ds-demo-q6b5f 1/1 Running 0 100m 10.244.2.80 node02.k8s.org <none> <none> job-demo-4h9gb 0/1 Completed 0 10m 10.244.3.70 node03.k8s.org <none> <none> job-multi-demo-rbw7d 1/1 Running 0 21s 10.244.1.70 node01.k8s.org <none> <none> [root@master01 ~]# kubectl get pods -o wide NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES ds-demo-8d7g9 1/1 Running 0 101m 10.244.3.69 node03.k8s.org <none> <none> ds-demo-dkxfs 1/1 Running 0 101m 10.244.1.69 node01.k8s.org <none> <none> ds-demo-dtsgc 1/1 Running 0 101m 10.244.4.13 node04.k8s.org <none> <none> ds-demo-q6b5f 1/1 Running 0 101m 10.244.2.80 node02.k8s.org <none> <none> job-demo-4h9gb 0/1 Completed 0 10m 10.244.3.70 node03.k8s.org <none> <none> job-multi-demo-f7rz4 1/1 Running 0 21s 10.244.3.71 node03.k8s.org <none> <none> job-multi-demo-rbw7d 0/1 Completed 0 43s 10.244.1.70 node01.k8s.org <none> <none> [root@master01 ~]#
提示：默认情况没有指定并行度，其并行度为1,即pod和pod之间就是串行执行任务；
定义并行度
[root@master01 ~]# cat job-multi.yaml
apiVersion: batch/v1
kind: Job
metadata:
name: job-multi-demo2
spec:
completions: 6
parallelism: 2
template:
metadata:
labels:
app: myjob
spec:
containers:
- name: myjob
image: alpine
command: ["/bin/sh", "-c", "sleep 10"]
restartPolicy: Never
[root@master01 ~]#
提示：定义并行度需要在spec字段下使用parallelism字段来指定，所谓并行度指一次并行运行几个pod，上述配置表示一次运行2个pod；即2个pod同时作业；
应用配置清单
[root@master01 ~]# kubectl apply -f job-multi.yaml job.batch/job-multi-demo2 created [root@master01 ~]# kubectl get jobs -o wide NAME COMPLETIONS DURATION AGE CONTAINERS IMAGES SELECTOR job-demo 1/1 18s 18m myjob alpine controller-uid=4ded17a8-fc39-480e-8f37-6bb2bd328997 job-multi-demo 6/6 116s 8m49s myjob alpine controller-uid=80f44cbd-f7e5-4eb4-a286-39bfcfc9fe39 job-multi-demo2 0/6 8s 8s myjob alpine controller-uid=d40f47ea-e58d-4424-97bd-7fda6bdf4e43 [root@master01 ~]# kubectl get pod -o wide NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES ds-demo-8d7g9 1/1 Running 0 109m 10.244.3.69 node03.k8s.org <none> <none> ds-demo-dkxfs 1/1 Running 0 109m 10.244.1.69 node01.k8s.org <none> <none> ds-demo-dtsgc 1/1 Running 0 110m 10.244.4.13 node04.k8s.org <none> <none> ds-demo-q6b5f 1/1 Running 0 109m 10.244.2.80 node02.k8s.org <none> <none> job-demo-4h9gb 0/1 Completed 0 18m 10.244.3.70 node03.k8s.org <none> <none> job-multi-demo-f7rz4 0/1 Completed 0 8m44s 10.244.3.71 node03.k8s.org <none> <none> job-multi-demo-hhcrm 0/1 Completed 0 7m23s 10.244.3.72 node03.k8s.org <none> <none> job-multi-demo-kjmld 0/1 Completed 0 8m20s 10.244.2.81 node02.k8s.org <none> <none> job-multi-demo-lfzrj 0/1 Completed 0 8m1s 10.244.2.82 node02.k8s.org <none> <none> job-multi-demo-rbw7d 0/1 Completed 0 9m6s 10.244.1.70 node01.k8s.org <none> <none> job-multi-demo-vdkrm 0/1 Completed 0 7m41s 10.244.2.83 node02.k8s.org <none> <none> job-multi-demo2-66tdd 0/1 Completed 0 25s 10.244.2.84 node02.k8s.org <none> <none> job-multi-demo2-fsl9r 0/1 Completed 0 25s 10.244.3.73 node03.k8s.org <none> <none> job-multi-demo2-js7qs 1/1 Running 0 9s 10.244.2.85 node02.k8s.org <none> <none> job-multi-demo2-nqmps 1/1 Running 0 12s 10.244.1.71 node01.k8s.org <none> <none> [root@master01 ~]# kubectl get pod -o wide NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES ds-demo-8d7g9 1/1 Running 0 110m 10.244.3.69 node03.k8s.org <none> <none> ds-demo-dkxfs 1/1 Running 0 109m 10.244.1.69 node01.k8s.org <none> <none> ds-demo-dtsgc 1/1 Running 0 110m 10.244.4.13 node04.k8s.org <none> <none> ds-demo-q6b5f 1/1 Running 0 109m 10.244.2.80 node02.k8s.org <none> <none> job-demo-4h9gb 0/1 Completed 0 19m 10.244.3.70 node03.k8s.org <none> <none> job-multi-demo-f7rz4 0/1 Completed 0 8m57s 10.244.3.71 node03.k8s.org <none> <none> job-multi-demo-hhcrm 0/1 Completed 0 7m36s 10.244.3.72 node03.k8s.org <none> <none> job-multi-demo-kjmld 0/1 Completed 0 8m33s 10.244.2.81 node02.k8s.org <none> <none> job-multi-demo-lfzrj 0/1 Completed 0 8m14s 10.244.2.82 node02.k8s.org <none> <none> job-multi-demo-rbw7d 0/1 Completed 0 9m19s 10.244.1.70 node01.k8s.org <none> <none> job-multi-demo-vdkrm 0/1 Completed 0 7m54s 10.244.2.83 node02.k8s.org <none> <none> job-multi-demo2-5f5tn 1/1 Running 0 9s 10.244.1.72 node01.k8s.org <none> <none> job-multi-demo2-66tdd 0/1 Completed 0 38s 10.244.2.84 node02.k8s.org <none> <none> job-multi-demo2-fsl9r 0/1 Completed 0 38s 10.244.3.73 node03.k8s.org <none> <none> job-multi-demo2-js7qs 0/1 Completed 0 22s 10.244.2.85 node02.k8s.org <none> <none> job-multi-demo2-md84p 1/1 Running 0 9s 10.244.3.74 node03.k8s.org <none> <none> job-multi-demo2-nqmps 0/1 Completed 0 25s 10.244.1.71 node01.k8s.org <none> <none> [root@master01 ~]#
提示：可以看到现在pod就一次运行两个；
3、CronJob控制器
这种类型的控制器主要用来创建周期性任务pod；
示例：定义CronJob控制器
[root@master01 ~]# cat cronjob-demo.yaml
apiVersion: batch/v1beta1
kind: CronJob
metadata:
name: cronjob-demo
labels:
app: mycronjob
spec:
schedule: "*/2 * * * *"
jobTemplate:
metadata:
labels:
app: mycronjob-jobs
spec:
parallelism: 2
template:
spec:
containers:
- name: myjob
image: alpine
command:
- /bin/sh
- -c
- date; echo Hello from the Kubernetes cluster; sleep 10
restartPolicy: OnFailure
[root@master01 ~]#
提示：定义cronjob控制器，最主要是定义job模板；其实cronjob控制器是通过job控制器来管理pod，这个逻辑有点类似deploy控制器通过rs来控制pod；其中schedule字段用来指定周期性调度时间策略，这个定义和我们在linux上定义周期性任务一样；对于job模板和我们定义job一样；以上配置表示每2分钟执行一次job模板中的定义的job任务；其每次并行运行2个pod；
执行配置清单
[root@master01 ~]# kubectl apply -f cronjob-demo.yaml cronjob.batch/cronjob-demo created [root@master01 ~]# kubectl get cronjob -o wide NAME SCHEDULE SUSPEND ACTIVE LAST SCHEDULE AGE CONTAINERS IMAGES SELECTOR cronjob-demo */2 * * * * False 0 <none> 12s myjob alpine <none> [root@master01 ~]# kubectl get pod NAME READY STATUS RESTARTS AGE cronjob-demo-1608307560-5hwmb 1/1 Running 0 9s cronjob-demo-1608307560-rgkkr 1/1 Running 0 9s ds-demo-8d7g9 1/1 Running 0 125m ds-demo-dkxfs 1/1 Running 0 125m ds-demo-dtsgc 1/1 Running 0 125m ds-demo-q6b5f 1/1 Running 0 125m job-demo-4h9gb 0/1 Completed 0 34m job-multi-demo-f7rz4 0/1 Completed 0 24m job-multi-demo-hhcrm 0/1 Completed 0 23m job-multi-demo-kjmld 0/1 Completed 0 24m job-multi-demo-lfzrj 0/1 Completed 0 23m job-multi-demo-rbw7d 0/1 Completed 0 25m job-multi-demo-vdkrm 0/1 Completed 0 23m job-multi-demo2-5f5tn 0/1 Completed 0 15m job-multi-demo2-66tdd 0/1 Completed 0 16m job-multi-demo2-fsl9r 0/1 Completed 0 16m job-multi-demo2-js7qs 0/1 Completed 0 16m job-multi-demo2-md84p 0/1 Completed 0 15m job-multi-demo2-nqmps 0/1 Completed 0 16m [root@master01 ~]#
提示：可以看到对应就有两个pod正在运行；
查看是否创建的有job控制器呢？
[root@master01 ~]# kubectl get job -o wide NAME COMPLETIONS DURATION AGE CONTAINERS IMAGES SELECTOR cronjob-demo-1608307560 2/1 of 2 15s 3m18s myjob alpine controller-uid=4a84b474-b890-4dd2-80d4-a6115130785a cronjob-demo-1608307680 2/1 of 2 17s 77s myjob alpine controller-uid=affecad9-03e6-430c-8c58-c845773c8ff7 job-demo 1/1 18s 37m myjob alpine controller-uid=4ded17a8-fc39-480e-8f37-6bb2bd328997 job-multi-demo 6/6 116s 28m myjob alpine controller-uid=80f44cbd-f7e5-4eb4-a286-39bfcfc9fe39 job-multi-demo2 6/6 46s 19m myjob alpine controller-uid=d40f47ea-e58d-4424-97bd-7fda6bdf4e43 [root@master01 ~]#
提示：有两个job控制器，名字都一样；从上面显示的结果，不难理解，cronjob每执行一次，它都会调用对应的job控制来创建新pod；
作者：Linux-1874
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