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pod控制器是用于实现管理pod的中间层，确保pod资源符合预期的状态，pod的资源出现故障时，会尝试 进行重启，当根据重启策略无效，则会重新新建pod的资源。
本文主要讲解replicaset、deployment、daemonset 三中类型的pod控制器。
（1）什么是replicaset？
replicaset是下一代复本控制器，是replication controller（rc）的升级版本。replicaset和 replication controller之间的唯一区别是对选择器的支持。replicaset支持labels user guide中描述的set-based选择器要求， 而replication controller仅支持equality-based的选择器要求。
（2）如何使用replicaset
大多数kubectl 支持replication controller 命令的也支持replicasets。rolling-update命令除外，如果要使用rolling-update，请使用deployments来实现。
虽然replicasets可以独立使用，但它主要被 deployments用作pod 机制的创建、删除和更新。当使用deployment时，你不必担心创建pod的replicasets，因为可以通过deployment实现管理replicasets。
（3）何时使用replicaset？
replicaset能确保运行指定数量的pod。然而，deployment 是一个更高层次的概念，它能管理replicasets，并提供对pod的更新等功能。因此，我们建议你使用deployment来管理replicasets，除非你需要自定义更新编排。
这意味着你可能永远不需要操作replicaset对象，而是使用deployment替代管理 。后续讲解deployment会详细描述。
（1）编写yaml文件，并创建启动
简单创建一个replicaset：启动2个pod
我要评论[root@master manifests]# vim rs-damo.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
[root@master manifests]# kubectl create -f rs-damo.yaml
replicaset.apps/myapp created
（2）查询验证
---查询replicaset(rs)信息
[root@master manifests]# kubectl get rs
name desired current ready age
myapp 2 2 2 23s
---查询pod信息
[root@master manifests]# kubectl get pods
name ready status restarts age
myapp-r4ss4 1/1 running 0 25s
myapp-zjc5l 1/1 running 0 26s
---查询pod详细信息；模板中的label都生效了
[root@master manifests]# kubectl describe pod myapp-r4ss4
name: myapp-r4ss4
namespace: default
priority: 0
priorityclassname: <none>
node: node2/192.168.130.105
start time: thu, 06 sep 2018 14:57:23 +0800
labels: app=myapp
environment=qa
release=canary
... ...
---验证服务
[root@master manifests]# curl 10.244.2.13
hello myapp | version: v1 | <a href="hostname.html">pod name</a>
（3）生成pod原则：“多退少补”
① 删除pod，会立即重新构建，生成新的pod
[root@master manifests]# kubectl delete pods myapp-zjc5l
pod "myapp-k4j6h" deleted
[root@master ~]# kubectl get pods
name ready status restarts age
myapp-r4ss4 1/1 running 0 33s
myapp-mdjvh 1/1 running 0 10s
② 若另一个pod，不小心符合了rs的标签选择器，就会随机干掉一个此标签的pod
---随便启动一个pod
[root@master manifests]# kubectl get pods --show-labels
name ready status restarts age labels
myapp-hxgbh 1/1 running 0 7m app=myapp,environment=qa,release=canary
myapp-mdjvh 1/1 running 0 6m app=myapp,environment=qa,release=canary
pod-test 1/1 running 0 13s app=myapp,tier=frontend
---将pod-test打上release=canary标签
[root@master manifests]# kubectl label pods pod-test release=canary
pod/pod-test labeled
---随机停掉一个pod
[root@master manifests]# kubectl get pods --show-labels
name ready status restarts age labels
myapp-hxgbh 1/1 running 0 8m app=myapp,environment=qa,release=canary
myapp-mdjvh 1/1 running 0 7m app=myapp,environment=qa,release=canary
pod-test 0/1 terminating 0 1m app=myapp,release=canary,tier=frontend
（1）使用edit 修改rs 配置，将副本数改为5；即可实现动态扩容
[root@master manifests]# kubectl edit rs myapp
... ...
spec:
replicas: 5
... ...
replicaset.extensions/myapp edited
（2）验证
[root@master manifests]# kubectl get pods
name ready status restarts age
client 0/1 error 0 1d
myapp-bck7l 1/1 running 0 16s
myapp-h8cqr 1/1 running 0 16s
myapp-hfb72 1/1 running 0 6m
myapp-r4ss4 1/1 running 0 9m
myapp-vvpgf 1/1 running 0 16s
（1）使用edit 修改rs 配置，将容器的镜像改为v2版；即可实现在线升级版本
[root@master manifests]# kubectl edit rs myapp
... ...
spec:
containers:
- image: ikubernetes/myapp:v2
... ...
replicaset.extensions/myapp edited
（2）查询rs，已经完成修改
[root@master manifests]# kubectl get rs -o wide
name desired current ready age containers images selector
myapp 5 5 5 11m myapp-container ikubernetes/myapp:v2 app=myapp,release=canary
（3）但是，修改完并没有升级
需删除pod，再自动生成新的pod时，就会升级成功；
即可以实现灰度发布：删除一个，会自动启动一个版本升级成功的pod
---访问没有删除pod的服务，显示是v1版
[root@master manifests]# curl 10.244.2.15
hello myapp | version: v1 | <a href="hostname.html">pod name</a>
---删除一个pod，访问新生成pod的服务，版本升级为v2版
[root@master manifests]# kubectl delete pod myapp-bck7l
pod "myapp-bck7l" deleted
[root@master ~]# kubectl get pods -o wide
name ready status restarts age ip node
myapp-hxgbh 1/1 running 0 20m 10.244.1.17 node1
[root@master manifests]# curl 10.244.1.17
hello myapp | version: v2 | <a href="hostname.html">pod name</a>
（1）介绍
deployment 为 pod和replica set 提供了一个声明式定义(declarative)方法，用来替代以前的replicationcontroller来方便的管理应用
你只需要在 deployment 中描述您想要的目标状态是什么，deployment controller 就会帮您将 pod 和replicaset 的实际状态改变到您的目标状态。您可以定义一个全新的 deployment 来创建 replicaset 或者删除已有的 deployment 并创建一个新的来替换。
注意：您不该手动管理由 deployment 创建的 replica set，否则您就篡越了 deployment controller 的职责！
（2）典型的应用场景包括
（1）创建一个简单的replicaset，启动2个pod
[root@master manifests]# vim deploy-damo.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
[root@master manifests]# kubectl apply -f deploy-damo.yaml
deployment.apps/myapp-deploy configured
注：apply 声明式创建启动；和create差不多；但是可以对一个文件重复操作；create不可以。
（2）查询验证
---查询deployment信息
[root@master manifests]# kubectl get deploy
name desired current up-to-date available age
myapp-deploy 2 2 2 2 14s
---查询replicaset信息；deployment会先生成replicaset
[root@master manifests]# kubectl get rs
name desired current ready age
myapp-deploy-69b47bc96d 2 2 2 28s
---查询pod信息；replicaset会再创建pod
[root@master manifests]# kubectl get pods
name ready status restarts age
myapp-deploy-69b47bc96d-bm8zc 1/1 running 0 18s
myapp-deploy-69b47bc96d-pjr5v 1/1 running 0 18s
有2中方法实现
（1）方法1：直接修改yaml文件，将副本数改为3
[root@master manifests]# vim deploy-damo.yaml
... ...
spec:
replicas: 3
... ...
[root@master manifests]# kubectl apply -f deploy-damo.yaml
deployment.apps/myapp-deploy configured
查询验证成功：有3个pod
[root@master manifests]# kubectl get pods
name ready status restarts age
myapp-deploy-69b47bc96d-bcdnq 1/1 running 0 25s
myapp-deploy-69b47bc96d-bm8zc 1/1 running 0 2m
myapp-deploy-69b47bc96d-pjr5v 1/1 running 0 2m
（2）通过patch命令打补丁命令扩容
与方法1的区别：不需修改yaml文件；平常测试时使用方便；
但列表格式复杂，极容易出错
[root@master manifests]# kubectl patch deployment myapp-deploy -p '{"spec":{"replicas":5}}'
deployment.extensions/myapp-deploy patched
查询验证成功：有5个pod
[root@master ~]# kubectl get pods
name ready status restarts age
myapp-deploy-67f6f6b4dc-2756p 1/1 running 0 26s
myapp-deploy-67f6f6b4dc-2lkwr 1/1 running 0 26s
myapp-deploy-67f6f6b4dc-knttd 1/1 running 0 21m
myapp-deploy-67f6f6b4dc-ms7t2 1/1 running 0 21m
myapp-deploy-67f6f6b4dc-vl2th 1/1 running 0 21m
（1）直接修改deploy-damo.yaml
[root@master manifests]# vim deploy-damo.yaml
... ...
spec:
containers:
- name: myapp
image: ikubernetes/myapp:v2
... ...
（2）可以动态监控版本升级
[root@master ~]# kubectl get pods -w
发现是滚动升级，先停一个，再开启一个新的（升级）；再依次听一个...
（3）验证：访问服务，版本升级成功
[root@master ~]# kubectl get pods -o wide
name ready status restarts age ip node
myapp-deploy-67f6f6b4dc-6lv66 1/1 running 0 2m 10.244.1.75 node1
[root@master ~]# curl 10.244.1.75
hello myapp | version: v2 | <a href="hostname.html">pod name</a>
（1）方法1：修改yaml文件
[root@master manifests]# vim deploy-damo.yaml
... ...
strategy:
rollingupdate:
maxsurge: 1 #每次更新一个pod
maxunavailable: 0 #最大不可用pod为0
... ...
（2）打补丁：修改更新策略
[root@master manifests]# kubectl patch deployment myapp-deploy -p '{"spec":{"strategy":{"rollingupdate":{"maxsurge":1,"maxunavailable":0}}}}'
deployment.extensions/myapp-deploy patched
（3）验证：查询详细信息
[root@master manifests]# kubectl describe deployment myapp-deploy
... ...
rollingupdatestrategy: 0 max unavailable, 1 max surge
... ...
（4）升级到v3版
① 金丝雀发布：先更新一个pod，然后立即暂停，等版本运行没问题了，再继续发布
[root@master manifests]# kubectl set image deployment myapp-deploy myapp=ikubernetes/myapp:v3 && kubectl rollout pause deployment myapp-deploy
deployment.extensions/myapp-deploy image updated #一个pod更新成功
deployment.extensions/myapp-deploy paused #暂停更新
② 等版本运行没问题了，解除暂停，继续发布更新
[root@master manifests]# kubectl rollout resume deployment myapp-deploy
deployment.extensions/myapp-deploy resumed
③ 中间可以一直监控过程
[root@master ~]# kubectl rollout status deployment myapp-deploy #输出版本更新信息
waiting for deployment "myapp-deploy" rollout to finish: 1 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: 1 out of 5 new replicas have been updated...
waiting for deployment "myapp-deploy" rollout to finish: 1 out of 5 new replicas have been updated...
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: 2 out of 5 new replicas have been updated...
---也可以使用get查询pod 更新过程
[root@master ~]# kubectl get pods -w
④ 验证：随便访问一个pod的服务，版本升级成功
[root@master ~]# kubectl get pods -o wide
name ready status restarts age ip node
myapp-deploy-6bdcd6755d-2bnsl 1/1 running 0 1m 10.244.1.77 node1
[root@master ~]# curl 10.244.1.77
hello myapp | version: v3 | <a href="hostname.html">pod name</a>
（1）命令
查询版本变更历史
$ kubectl rollout history deployment deployment_name
undo回滚版本；--to-revision= 回滚到第几版本
$ kubectl rollout undo deployment deployment_name --to-revision=n
（2）演示
---查询版本变更历史
[root@master manifests]# kubectl rollout history deployment myapp-deploy
deployments "myapp-deploy"
revision change-cause
1 <none>
2 <none>
3 <none>
---回滚到第1版本
[root@master manifests]# kubectl rollout undo deployment myapp-deploy --to-revision=1
deployment.extensions/myapp-deploy
[root@master manifests]# kubectl rollout history deployment myapp-deploy
deployments "myapp-deploy"
revision change-cause
2 <none>
3 <none>
4 <none>
（3）查询验证，已经回到v1版了
[root@master manifests]# kubectl get rs -o wide
name desired current ready age containers images selector
myapp-deploy-67f6f6b4dc 0 0 0 18h myapp ikubernetes/myapp:v2 app=myapp,pod-template-hash=2392926087,release=canary
myapp-deploy-69b47bc96d 5 5 5 18h myapp ikubernetes/myapp:v1 app=myapp,pod-template-hash=2560367528,release=canary
myapp-deploy-6bdcd6755d 0 0 0 10m myapp ikubernetes/myapp:v3 app=myapp,pod-template-hash=2687823118,release=canary
（1）介绍
daemonset保证在每个node上都运行一个容器副本，常用来部署一些集群的日志、监控或者其他系统管理应用
（2）典型的应用包括
（1）创建并创建一个简单的daemonset，启动pod，只后台运行filebeat手机日志服务
[root@master manifests]# vim ds-demo.yaml
apiversion: apps/v1
kind: daemonset
metadata:
name: filebeat-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
[root@master manifests]# kubectl apply -f ds-demo.yaml
daemonset.apps/myapp-ds created
（2）查询验证
[root@master ~]# kubectl get ds
name desired current ready up-to-date available node selector age
filebeat-ds 2 2 2 2 2 <none> 6m
[root@master ~]# kubectl get pods
name ready status restarts age
filebeat-ds-r25hh 1/1 running 0 4m
filebeat-ds-vvntb 1/1 running 0 4m
[root@master ~]# kubectl exec -it filebeat-ds-r25hh -- /bin/sh
/ # ps aux
pid user time command
1 root 0:00 /usr/local/bin/filebeat -e -c /etc/filebeat/filebeat.yml
（1）使用kubectl set image 命令更新pod的镜像；实现版本升级
[root@master ~]# kubectl set image daemonsets filebeat-ds filebeat=ikubernetes/filebeat:5.6.6-alpine
daemonset.extensions/filebeat-ds image updated
（2）验证，升级成功
[root@master ~]# kubectl get ds -o wide
name desired current ready up-to-date available node selector age containers images selector
filebeat-ds 2 2 2 2 2 <none> 7m filebeat ikubernetes/filebeat:5.6.6-alpine app=filebeat,release=stable
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