Pod分爲自主式pod和受controller管理的pod。學習總結(3)中所創建的pod皆爲自主式pod，本篇總結受controller管理的pod。本篇中所涉及到的controller未加特殊說明時都表示pod Controller。
Pod controller
pod controller 是管理pod的中間層，保障pod 資源的狀態與用戶的期望狀態保持一致。
pod controller 有多種：
1) ReplicaSet (代替用戶創建管理無狀態的pod副本，並保證副本數據與用戶期望一致, 實現擴、縮容等操作)， 它也是新一代的ReplicationController；kubernetes 不建議直接使用replicaSet，而建議使用Deployment，它工作在replicaSet之上，它不直接控制pod，而是直接控制replicaSet，進而控制 pod。它還支持滾動更新、回滾等，提供了聲明式配置的功能 。
2) DaemonSet ： 用於確保cluster中的每一個node,只運行一個特定的pod副本。實現一些OS級的守護任務。也可以在cluster的部分節點上，每個node 只運行一個特定的pod副本。
3) Deployment、DaemonSet 都是無狀態的，都有守護進程，常駐內存的。
4) Job控制器：保障任務只執行一次。
5) cronJob控制器：週期運行某一任務。
6) StatefullSet: 管理有狀態應用。
node 與 pod 之間沒有一一對應的關係。
controller 配置清單中的核心資源有： 1、用戶期望的副本數； 2、標籤選擇器；3、pod資源模板
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]#說明：
將image中的版本改爲nginx:1.15-alpine並保存退出，然後container 不會自動升爲1.15-alpine，需要手工刪除舊container時，contrller自動創建的新container就會升級爲1.15-alpine了。這種刪除一個pod，然後k8s自動再創建一個新版本的pod，稱爲canary的滾動升級。
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]#
說明：rs name規律爲 deployment name + template name的hash值 ; pods name規律爲 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]# 說明：把 deploy-demo.yaml 中的 relicas 改爲3 ，然後再次 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
......
說明：如果StrategyType爲 rollingUpdate，就可以設置RollingUpdateStrategy字段，該字段值有maxSurge (超出多少，可以指定數量或百分比)、maxUnavailable (最多有多少個不可用，可以指定數值或百分比)
[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]#
說明：把deploy-demo.yaml 中的 image 版本改變爲1.15-alpine，然後再 kubectl apply -f deploy-demo.yaml，然後使用kubectl get pods -l app=nginx -w 查看更新的過程
[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]#
說明：
kubect get rs -o wide 查看各版本的現狀
kubectl rollout history 查看回滾歷史
kubectl rollout status 查看回滾狀態
kubectl rollout undo 回滾到前一個版本，也可以使用--to-reversion=1 參考回滾到第一個版本
kubectl rollout pause 暫停回滾
kubectl rollout resume 恢復回滾
還可以指定 deploy.spec下的 revisionHistoryLimit ，表示滾動升級時最多保存的舊版本數量
[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]#說明：DaemonSet 默認會在每個非master 節點各運行一個。
例4-Service:
由於pod有生命週期，所以在client與pod之間使用了service層，service依賴CoreDNS、kube-dns。
kube-proxy 始終監控着API server上有關 service 的變動信息，此過程稱爲watch 。
service的實現方式有三種，userspace、iptables、ipvs，原理如下圖所示：
[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說明：
clusterIP 只能內部使用。內部資源記錄的格式爲：SVC_NAME.NS_NAME.DOMAIN.LTD。默認後綴爲 svc.cluster.local.
NodePort 可提供外部訪問，訪問路徑 client request --> NodeIP:nodePort --> ClusterIP:ServicePort-->PodIP:containerPort
ExternalName 把集羣外部的一個服務映射到集羣內部使用。它通常是一個FQDN的CNAME名稱 ，並指向另一個外部的FQDN名稱。可以達到 讓pods訪問外部服務的目的。
No ClusterIP: 稱爲 Headless Service。它可以把servicename名稱直接解析到podIP，所以無需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]#
可以在集羣外的任何一臺host上 訪問
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說明：(可以通過以下命令設置sessionAffinity選項)
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]#說明：No ClusterIP: 稱爲 Headless Service。它可以把servicename名稱直接解析到podIP，所以無需clusterIP。