Pod分为自主式pod和受controller管理的pod。学习总结(3)中所创建的pod皆为自主式pod，本篇总结受controller管理的pod。本篇中所涉及到的controller未加特殊说明时都表示pod Controller。
Pod controller
pod controller 是管理pod的中间层，保障pod 资源的状态与用户的期望状态保持一致。
pod controller 有多种：
1) ReplicaSet (代替用户创建管理无状态的pod副本，并保证副本数据与用户期望一致, 实现扩、缩容等操作)， 它也是新一代的ReplicationController；kubernetes 不建议直接使用replicaSet，而建议使用Deployment，它工作在replicaSet之上，它不直接控制pod，而是直接控制replicaSet，进而控制 pod。它还支持滚动更新、回滚等，提供了声明式配置的功能 。
2) DaemonSet ： 用于确保cluster中的每一个node,只运行一个特定的pod副本。实现一些OS级的守护任务。也可以在cluster的部分节点上，每个node 只运行一个特定的pod副本。
3) Deployment、DaemonSet 都是无状态的，都有守护进程，常驻内存的。
4) Job控制器：保障任务只执行一次。
5) cronJob控制器：周期运行某一任务。
6) StatefullSet: 管理有状态应用。
node 与 pod 之间没有一一对应的关系。
controller 配置清单中的核心资源有： 1、用户期望的副本数； 2、标签选择器；3、pod资源模板
例1-ReplicaSet:
[root@docker79 manifests]# mkdir controller
[root@docker79 manifests]# cd controller/
[root@docker79 controller]# vim rs-demo.yaml
[root@docker79 controller]# cat rs-demo.yaml
apiVersion: apps/v1
kind: ReplicaSet
metadata:
name: nginx-rs
namespace: default
spec:
replicas: 2
selector:
matchLabels:
app: nginx
release: canary
template:
metadata:
name: nginx-pod
labels:
app: nginx
release: canary
environment: qa
spec:
containers:
- name: nginx-container
image: nginx:1.14-alpine
ports:
- name: http
containerPort: 80
[root@docker79 controller]# kubectl apply -f rs-demo.yaml
replicaset.apps/nginx-rs created
[root@docker79 controller]# kubectl get pods -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE
nginx-rs-hncc9 1/1 Running 0 1m 10.244.1.17 docker78 <none>
nginx-rs-wnxnx 1/1 Running 0 1m 10.244.2.11 docker77 <none>
[root@docker79 controller]# curl -I http://10.244.1.17
HTTP/1.1 200 OK
Server: nginx/1.14.0
Date: Thu, 27 Sep 2018 02:16:14 GMT
Content-Type: text/html
Content-Length: 612
Last-Modified: Wed, 12 Sep 2018 00:04:31 GMT
Connection: keep-alive
ETag: "5b98580f-264"
Accept-Ranges: bytes
[root@docker79 controller]#
[root@docker79 controller]# kubectl get rs
NAME DESIRED CURRENT READY AGE
nginx-rs 2 2 2 2m
[root@docker79 controller]# kubectl edit rs nginx-rs
replicaset.extensions/nginx-rs edited
[root@docker79 controller]#说明：
将image中的版本改为nginx:1.15-alpine并保存退出，然后container 不会自动升为1.15-alpine，需要手工删除旧container时，contrller自动创建的新container就会升级为1.15-alpine了。这种删除一个pod，然后k8s自动再创建一个新版本的pod，称为canary的滚动升级。
接上
[root@docker79 controller]# kubectl delete pod nginx-rs-hncc9
pod "nginx-rs-hncc9" deleted
[root@docker79 controller]# kubectl get pods -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE
nginx-rs-6tnz5 1/1 Running 0 22s 10.244.1.18 docker78 <none>
nginx-rs-wnxnx 1/1 Running 0 11m 10.244.2.11 docker77 <none>
[root@docker79 controller]# curl -I 10.244.1.18
HTTP/1.1 200 OK
Server: nginx/1.15.4
Date: Thu, 27 Sep 2018 02:27:18 GMT
Content-Type: text/html
Content-Length: 612
Last-Modified: Tue, 25 Sep 2018 17:23:56 GMT
Connection: keep-alive
ETag: "5baa6f2c-264"
Accept-Ranges: bytes
[root@docker79 controller]#
[root@docker79 controller]# kubectl delete -f rs-demo.yaml
replicaset.apps "nginx-rs" deleted
例2-Deployment:
[root@docker79 controller]# vim deploy-demo.yaml
[root@docker79 controller]# cat deploy-demo.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
name: nginx-deploy
namespace: default
spec:
replicas: 2
selector:
matchLabels:
app: nginx
release: canary
template:
metadata:
labels:
app: nginx
release: canary
spec:
containers:
- name: nginx-container
image: nginx:1.14-alpine
ports:
- name: http
containerPort: 80
[root@docker79 controller]# kubectl apply -f deploy-demo.yaml
deployment.apps/nginx-deploy created
[root@docker79 controller]# kubectl get pods -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE
nginx-deploy-688454bc5d-ft8wm 1/1 Running 0 17s 10.244.1.19 docker78 <none>
nginx-deploy-688454bc5d-pnmpn 1/1 Running 0 17s 10.244.2.12 docker77 <none>
[root@docker79 controller]# kubectl get rs
NAME DESIRED CURRENT READY AGE
nginx-deploy-688454bc5d 2 2 2 35s
[root@docker79 controller]# kubectl get deploy
NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE
nginx-deploy 2 2 2 2 46s
[root@docker79 controller]#
说明：rs name规律为 deployment name + template name的hash值 ; pods name规律为 rs name + hash值
[root@docker79 controller]# vim deploy-demo.yaml
[root@docker79 controller]# grep replicas deploy-demo.yaml
replicas: 3
[root@docker79 controller]# kubectl apply -f deploy-demo.yaml
deployment.apps/nginx-deploy configured
[root@docker79 controller]# kubectl get pods
NAME READY STATUS RESTARTS AGE
nginx-deploy-688454bc5d-ft8wm 1/1 Running 0 5m
nginx-deploy-688454bc5d-pnmpn 1/1 Running 0 5m
nginx-deploy-688454bc5d-q24pr 1/1 Running 0 7s
[root@docker79 controller]# 说明：把 deploy-demo.yaml 中的 relicas 改为3 ，然后再次 kubectl apply -f deploy-demo.yaml
[root@docker79 controller]# kubectl describe deploy nginx-deploy
......
Replicas: 3 desired | 3 updated | 3 total | 3 available | 0 unavailable
StrategyType: RollingUpdate
MinReadySeconds: 0
RollingUpdateStrategy: 25% max unavailable, 25% max surge
......
说明：如果StrategyType为 rollingUpdate，就可以设置RollingUpdateStrategy字段，该字段值有maxSurge (超出多少，可以指定数量或百分比)、maxUnavailable (最多有多少个不可用，可以指定数值或百分比)
[root@docker79 controller]# vim deploy-demo.yaml
[root@docker79 controller]# grep image deploy-demo.yaml
image: nginx:1.15-alpine
[root@docker79 controller]# kubectl apply -f deploy-demo.yaml
deployment.apps/nginx-deploy configured
[root@docker79 controller]#
[root@docker79 controller]# kubectl get pods -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE
nginx-deploy-7488bbd64f-7vnps 1/1 Running 0 3m 10.244.1.22 docker78 <none>
nginx-deploy-7488bbd64f-nxlc2 1/1 Running 0 4m 10.244.1.21 docker78 <none>
nginx-deploy-7488bbd64f-v5qws 1/1 Running 0 4m 10.244.2.13 docker77 <none>
[root@docker79 controller]# curl -I http://10.244.1.22
HTTP/1.1 200 OK
Server: nginx/1.15.4
Date: Thu, 27 Sep 2018 02:53:28 GMT
Content-Type: text/html
Content-Length: 612
Last-Modified: Tue, 25 Sep 2018 17:23:56 GMT
Connection: keep-alive
ETag: "5baa6f2c-264"
Accept-Ranges: bytes
[root@docker79 controller]#
说明：把deploy-demo.yaml 中的 image 版本改变为1.15-alpine，然后再 kubectl apply -f deploy-demo.yaml，然后使用kubectl get pods -l app=nginx -w 查看更新的过程
[root@docker79 controller]# kubectl get rs -o wide
NAME DESIRED CURRENT READY AGE CONTAINERS IMAGES SELECTOR
nginx-deploy-688454bc5d 0 0 0 15m nginx-container nginx:1.14-alpine app=nginx,pod-template-hash=2440106718,release=canary
nginx-deploy-7488bbd64f 3 3 3 5m nginx-container nginx:1.15-alpine app=nginx,pod-template-hash=3044668209,release=canary
[root@docker79 controller]#
[root@docker79 controller]# kubectl rollout history deployment/nginx-deploy
deployments "nginx-deploy"
REVISION CHANGE-CAUSE
1 <none>
2 <none>
[root@docker79 controller]# kubectl rollout status deployment/nginx-deploy
deployment "nginx-deploy" successfully rolled out
[root@docker79 controller]# kubectl rollout undo deployment/nginx-deploy
deployment.extensions/nginx-deploy
[root@docker79 controller]# kubectl get rs -o wide
NAME DESIRED CURRENT READY AGE CONTAINERS IMAGES SELECTOR
nginx-deploy-688454bc5d 3 3 3 18m nginx-container nginx:1.14-alpine app=nginx,pod-template-hash=2440106718,release=canary
nginx-deploy-7488bbd64f 0 0 0 8m nginx-container nginx:1.15-alpine app=nginx,pod-template-hash=3044668209,release=canary
[root@docker79 controller]# kubectl get pods -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE
nginx-deploy-688454bc5d-7nvvm 1/1 Running 0 23s 10.244.2.14 docker77 <none>
nginx-deploy-688454bc5d-jts2x 1/1 Running 0 22s 10.244.1.24 docker78 <none>
nginx-deploy-688454bc5d-slkn7 1/1 Running 0 24s 10.244.1.23 docker78 <none>
[root@docker79 controller]# curl -I 10.244.1.24
HTTP/1.1 200 OK
Server: nginx/1.14.0
Date: Thu, 27 Sep 2018 02:58:26 GMT
Content-Type: text/html
Content-Length: 612
Last-Modified: Wed, 12 Sep 2018 00:04:31 GMT
Connection: keep-alive
ETag: "5b98580f-264"
Accept-Ranges: bytes
[root@docker79 controller]#
说明：
kubect get rs -o wide 查看各版本的现状
kubectl rollout history 查看回滚历史
kubectl rollout status 查看回滚状态
kubectl rollout undo 回滚到前一个版本，也可以使用--to-reversion=1 参考回滚到第一个版本
kubectl rollout pause 暂停回滚
kubectl rollout resume 恢复回滚
还可以指定 deploy.spec下的 revisionHistoryLimit ，表示滚动升级时最多保存的旧版本数量
[root@docker79 controller]# kubectl patch deployment nginx-deploy -p '{"spec":{"replicas":4}}'
deployment.extensions/nginx-deploy patched
[root@docker79 controller]# kubectl get pods
NAME READY STATUS RESTARTS AGE
nginx-deploy-688454bc5d-7nvvm 1/1 Running 0 7m
nginx-deploy-688454bc5d-bc94s 1/1 Running 0 11s
nginx-deploy-688454bc5d-jts2x 1/1 Running 0 7m
nginx-deploy-688454bc5d-slkn7 1/1 Running 0 8m
[root@docker79 controller]# kubectl delete -f deploy-demo.yaml
deployment.apps "nginx-deploy" deleted
[root@docker79 controller]#例3-DaemonSet：
[root@docker79 controller]# vim ds-demo.yaml
[root@docker79 controller]# cat 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
imagePullPolicy: IfNotPresent
env:
- name: REDIS_HOST
value: redis.default.svc.cluster.local
- name: REDIS_LOG_LEVEL
value: info
[root@docker79 controller]# kubectl apply -f ds-demo.yaml
daemonset.apps/filebeat-ds created
[root@docker79 controller]# kubectl get pods -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE
filebeat-ds-mzff4 1/1 Running 0 29s 10.244.1.25 docker78 <none>
filebeat-ds-zzl8q 1/1 Running 0 29s 10.244.2.16 docker77 <none>
[root@docker79 controller]#说明：DaemonSet 默认会在每个非master 节点各运行一个。
例4-Service:
由于pod有生命周期，所以在client与pod之间使用了service层，service依赖CoreDNS、kube-dns。
kube-proxy 始终监控着API server上有关 service 的变动信息，此过程称为watch 。
service的实现方式有三种，userspace、iptables、ipvs，原理如下图所示：
[root@docker79 controller]# vim svc-demo.yaml
[root@docker79 controller]# cat svc-demo.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
name: redis-deploy
namespace: default
spec:
replicas: 1
selector:
matchLabels:
app: redis
role: logstor
template:
metadata:
labels:
app: redis
role: logstor
spec:
containers:
- name: redis-container
image: redis:4.0-alpine
ports:
- name: redis
containerPort: 6379
---
apiVersion: v1
kind: Service
metadata:
name: redis-svc
namespace: default
spec:
selector:
app: redis
role: logstor
clusterIP: 10.97.97.97
type: ClusterIP
ports:
- name: redis-port
port: 6379
targetPort: 6379
[root@docker79 controller]# kubectl apply -f svc-demo.yaml
deployment.apps/redis-deploy created
service/redis-svc created
[root@docker79 controller]# kubectl get pods
NAME READY STATUS RESTARTS AGE
filebeat-ds-mzff4 1/1 Running 0 16m
filebeat-ds-zzl8q 1/1 Running 0 16m
redis-deploy-7587b96c74-ddbv8 1/1 Running 0 10s
[root@docker79 controller]#
[root@docker79 controller]# kubectl get svc
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 3d
redis-svc ClusterIP 10.97.97.97 <none> 6379/TCP 38s
[root@docker79 controller]# kubectl describe svc redis-svc
Name: redis-svc
Namespace: default
Labels: <none>
Annotations: kubectl.kubernetes.io/last-applied-configuration={"apiVersion":"v1","kind":"Service","metadata":{"annotations":{},"name":"redis-svc","namespace":"default"},"spec":{"clusterIP":"10.97.97.97","ports":[{...
Selector: app=redis,role=logstor
Type: ClusterIP
IP: 10.97.97.97
Port: redis-port 6379/TCP
TargetPort: 6379/TCP
Endpoints: 10.244.1.27:6379
Session Affinity: None
Events: <none>
[root@docker79 controller]#
Service Type说明：
clusterIP 只能内部使用。内部资源记录的格式为：SVC_NAME.NS_NAME.DOMAIN.LTD。默认后缀为 svc.cluster.local.
NodePort 可提供外部访问，访问路径 client request --> NodeIP:nodePort --> ClusterIP:ServicePort-->PodIP:containerPort
ExternalName 把集群外部的一个服务映射到集群内部使用。它通常是一个FQDN的CNAME名称 ，并指向另一个外部的FQDN名称。可以达到 让pods访问外部服务的目的。
No ClusterIP: 称为 Headless Service。它可以把servicename名称直接解析到podIP，所以无需clusterIP。
[root@docker79 controller]# vim svc-demo2.yaml
[root@docker79 controller]# vim deploy-demo.yaml
[root@docker79 controller]# kubectl apply -f deploy-demo.yaml
deployment.apps/nginx-deploy created
[root@docker79 controller]# cat svc-demo2.yaml
apiVersion: v1
kind: Service
metadata:
name: nginx-svc
namespace: default
spec:
selector:
app: nginx
release: canary
clusterIP: 10.99.99.99
type: NodePort
ports:
- name: httpport
port: 80
targetPort: 80
nodePort: 30080
[root@docker79 controller]# kubectl apply -f svc-demo2.yaml
service/nginx-svc created
[root@docker79 controller]#
[root@docker79 controller]# kubectl get pod -l release=canary
NAME READY STATUS RESTARTS AGE
nginx-deploy-7488bbd64f-7bp5k 1/1 Running 0 1m
nginx-deploy-7488bbd64f-ndqx9 1/1 Running 0 1m
[root@docker79 controller]# kubectl get svc
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 3d
nginx-svc NodePort 10.99.99.99 <none> 80:30080/TCP 26s
redis-svc ClusterIP 10.97.97.97 <none> 6379/TCP 12m
[root@docker79 controller]#
可以在集群外的任何一台host上 访问
yuandeMacBook-Pro:~ yuanjicai$ curl -I http://192.168.20.79:30080
HTTP/1.1 200 OK
Server: nginx/1.15.4
Date: Thu, 27 Sep 2018 04:01:11 GMT
Content-Type: text/html
Content-Length: 612
Last-Modified: Tue, 25 Sep 2018 17:23:56 GMT
Connection: keep-alive
ETag: "5baa6f2c-264"
Accept-Ranges: bytes
[root@docker79 controller]# kubectl delete -f svc-demo2.yaml
service "nginx-svc" deleted说明：(可以通过以下命令设置sessionAffinity选项)
kubectl patch svc nginx-svc -p '{"spec":{"sessionAffinity":"ClientIP"}}
kubectl describe svc nginx-svc
kubectl patch svc nginx-svc -p '{"spec":{"sessionAffinity":"None"}}
[root@docker79 controller]# vim svc-headless-demo.yaml
[root@docker79 controller]# cat svc-headless-demo.yaml
apiVersion: v1
kind: Service
metadata:
name: nginx-svc
namespace: default
spec:
selector:
app: nginx
release: canary
clusterIP: None
ports:
- name: httpport
port: 80
targetPort: 80
[root@docker79 controller]# kubectl apply -f svc-headless-demo.yaml
service/nginx-svc created
[root@docker79 controller]# kubectl describe svc nginx-svc
Name: nginx-svc
Namespace: default
Labels: <none>
Annotations: kubectl.kubernetes.io/last-applied-configuration={"apiVersion":"v1","kind":"Service","metadata":{"annotations":{},"name":"nginx-svc","namespace":"default"},"spec":{"clusterIP":"None","ports":[{"name":...
Selector: app=nginx,release=canary
Type: ClusterIP
IP: None
Port: httpport 80/TCP
TargetPort: 80/TCP
Endpoints: 10.244.1.28:80,10.244.2.17:80
Session Affinity: None
Events: <none>
[root@docker79 controller]#
[root@docker79 controller]# dig -t A nginx-svc.default.svc.cluster.local. @10.96.0.10
; <<>> DiG 9.9.4-RedHat-9.9.4-61.el7_5.1 <<>> -t A nginx-svc.default.svc.cluster.local. @10.96.0.10
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 55045
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 1
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;nginx-svc.default.svc.cluster.local. IN A
;; ANSWER SECTION:
nginx-svc.default.svc.cluster.local. 5 IN A 10.244.1.28
nginx-svc.default.svc.cluster.local. 5 IN A 10.244.2.17
;; Query time: 1 msec
;; SERVER: 10.96.0.10#53(10.96.0.10)
;; WHEN: 四 9月 27 12:09:25 CST 2018
;; MSG SIZE rcvd: 166
[root@docker79 controller]#说明：No ClusterIP: 称为 Headless Service。它可以把servicename名称直接解析到podIP，所以无需clusterIP。