Pod控制器：
ReplicationController，已废弃；
ReplicaSet，新一代的ReplicationController，管理无状态的pod资源，核心资源有3个，1用户期望的pod副本（按用户期望的创建指定的pod多退少补），2标签选择器，选定和管理自己的pod副本，3pod资源模板，完成pod资源的新建（自动扩缩容），k8s不建议直接使用ReplicaSet，而推荐用Deployment；
Deployment，建构在ReplicaSet之上，除支持ReplicaSet的功能，还支持滚动更新及回滚，还提供声明式配置（基于声明的逻辑重新定义，在运行中定义），管理无状态应用（关注群体而不关注个体）；
DaemonSet，系统级的功能，保证在集群中一个node上只运行1个Pod，无状态应用，必须是守护进程类的（不会终止）；
Job，要不要重新创建，要看任务是否完成，如要执行DB备份；
Cronjob，周期性的运行，如果前一个任务还没完，下次任务就来了；
StatefulSet，每个节点都有数据（有状态）要存储，把操作步骤写成脚本放入模板中，故障后启动会自动执行；
注：
TPR，third party resources，第三方资源，1.2+支持，1.7废弃；
CDR，custom defined resources，自定义资源，1.8+支持；
Operator，可将运维技能（操作步骤）灌进；
Helm，同linux的yum，简化运维技能；
kubectl explain rs #replicaSet，apps/v1，apps群组下的v1
kubectl explain rs.spec #replicas副本数量|selector|template
kubectl explain rs.spec.template #pod的metadata|spec，模板中定义的标签一定要与选择器中是一样的，否则会一直创建下去直接到k8s撑爆
kubectl explain rs.spec.template.spec
例：
vim rs-demo.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
kubectl create -f rs-demo.yaml
kubectl get rs
kubectl get pods --show-labels
kubectl describe pods myapp-XXX
curl 10.244.2.26
kubectl delete pods myapp-XXX #会自动创建
kubectl label pods pod-demo release=canary
kubectl get pods --show-labels #只剩1个了
kubectl delete pods pod-demo
kubectl get pods
kubectl edit rs myapp #replicas: 5，image: ikubenetes/myapp:v2
kubectl get pods
kubectl get rs -o wide
curl 10.244.1.17 #只有重建出的pod资源才是新版本的
kubectl delete pods myapp-XXX
kubectl get pods
curl 10.244.2.28 #v2，金丝雀发布，要手动干预，比如有5台服务器，先用2台跑v2，跑2天没问题后，再依次关掉其它3台，依次更新，
注：
蓝绿发布，replicaSet1有2个容器，v1，replicaSet2为新创建的，也2个容器，将service指向改到rs2上的2个；
以上金丝雀发布和蓝绿发布，都需要人为参与，而Deployment控制器可帮助我们专门做这个，而且可方便回滚；
Deployment，
提供滚动式自定义自控制式（如控制更新粒度）更新，
控制更新节奏和更新逻辑；
kubectl explain deploy #使用apps/v1
kubectl explain deploy.spec #多了strategy更新策略，revisionHistoryLimit默认10，paused
kubectl explain deploy.spec.strategy #type有Recreate|RollingUpdate
kubectl explain deploy.spec.strategy.rollingUpdate #控制更新粒度，maxSurge更新过程中超出目标副本的数量（可number或百分比）|maxUnavailable，这2个参数不能同时指定0，否则不能完成滚动更新
kubectl explain deploy.spec.template #pod的metadata|spec
例：
vim deploy-demo.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
kubectl apply -f deploy-demo.yaml #既可创建也可更新
kubectl get deploy
kubectl get rs #Deployment自动创建的，myapp-deploy-69b47bc96d，69b47bc96d为模板的hash值，不是随机的，可根据这个hash值追踪到模板sss
kubectl get pods
vim deploy-demo.yaml #改replicas为3
kubectl apply -f deploy-demo.yaml
kubectl get pods
kubectl describe deploy myapp-deploy #会自动添加一些Annotations，apply自动维护的，默认StrategyType是RollingUpdate，RollingUpdateStrategy:25% max unavailable 25% max surge
kubectl get pods -w #监控
kubectl get pods -l app=myapp -w
vim deploy-demo.yaml #ikubernetes/v2
kubectl apply deploy-demo.yaml #用-w查看更新过程
kubectl get rs -o wide
kubectl rollout history deployment myapp-deploy #rollout ondo用来回滚，rollout pause
kubectl patch deployment myapp-deploy -p '{"spec":{"replicas":5}}' #通过打补丁方式修改资源清单
kubectl get pods
kubectl patch deployment myapp-deploy -p '{"spec":{"strategy":{"rollingUpdate":{"maxSurge":1,"maxUnavailable":0}}}}'
kubectl describe deployment myapp-deploy #RollingUpdateStrategy
kubectl set image deployment myapp-deploy myapp=ikubernetes/myapp:v3 && kubectl rollout pause deployment myapp-deploy #金丝雀发布
kubectl get pods -l app=myapp -w
kubectl rollout status deployment myapp-deploy
kubectl rollout resume deployment myapp-deploy
kubectl get rs -o wide
kubectl rollout history deployment myapp-deploy #123
kubectl rollout undo deployment myapp-deploy --to-revisinotallow=1 #回滚到v1，v1就没有了，还原后为v4
kubectl get rs -o wide
kubectl explain ds
kubectl explain ds.spec
例：
vim ds-demo.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
name: redis
namespace: default
spec:
replicas: 1
selector:
matchLabels:
app: redis
role: logstore
template:
metadata:
labels:
app: redis
role: logstore
spec:
containers:
- name: redis
image: redis:4.8-alpine
ports:
- name: redis
containerPort: 6379
---
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
docker pull ikubernetes/filebeat:5.6.5-alpine
docker image inspect ikubernetes/filebeat:5.6.5-alpine
kubectl explain pods.spec.containers
kubectl apply -f ds-demo.yaml
kubectl get pods
kubectl logs myapp-ds-XXX
kubectl apply -f ds-demo.yaml
kubectl expose deployment redis --port=6379
kubectl get svc
kubectl get pods
kubectl exec -it redis-XXX-XXX -- /bin/sh
netstat -tnl
ls
nslookup redis.default.svc.cluster.local
redis-cli -h redis.default.svc.clsuter.local
keys *
exit
kubectl exec -it filebeat-ds-XXX -- /bin/sh
ps aux
cat /etc/filebeat/filebeat.yml
printenv
kill -1 1 #1为PID，-1为重载
kubectl describe ds filebeat
kubectl get pods -l app=filebeat -o wide #1个节点只运行1个
kubectl explain ds.spec.updateStrategy #OnDelete|RollingUpdate
kubectl explain ds.spec.updateStrategy.RollingUpdate #只有maxUnavailable
kubectl set image daemonsets filebeat filebeat=ikubernetes/filebeat:5.6.6-alpine
kubectl get pods -w
kubectl explain pods.spec #hostNetwork <boolean>，hostIPC <boolean>，hostPID <boolean>
