1.控制器的介绍
Pod 的分类：
自主式 Pod：Pod 退出后不会被创建
控制器管理的 Pod：在控制器的生命周期里，始终要维持 Pod 的副本数目
控制器类型：
Replication Controller和ReplicaSet
Deployment
DaemonSet
StatefulSet
Job
CronJob
HPA全称Horizontal Pod Autoscaler
Replication Controller和ReplicaSet
ReplicaSet 是下一代的 Replication Controller，官方推荐使用ReplicaSet。
ReplicaSet 和 Replication Controller 的唯一区别是选择器的支持，ReplicaSet 支持新的基于集合的选择器需求。ReplicaSet 确保任何时间都有指定数量的 Pod 副本在运行。虽然 ReplicaSets 可以独立使用，但今天它主要被Deployments 用作协调 Pod 创建、删除和更新的机制。
2.Deployment
Deployment 为 Pod 和 ReplicaSet 提供了一个申明式的定义方法。典型的应用场景： 用来创建Pod和ReplicaSet 、滚动更新和回滚、扩容和缩容、暂停与恢复。
3.DaemonSet
DaemonSet 确保全部（或者某些）节点上运行一个 Pod 的副本。当有节点加入集群时， 也会为他们新增一个 Pod 。当有节点从集群移除时，这些 Pod 也会被回收。删除 DaemonSet 将会删除它创建的所有 Pod。
DaemonSet 的典型用法：
• 在每个节点上运行集群存储 DaemonSet，例如 glusterd、ceph。
• 在每个节点上运行日志收集 DaemonSet，例如 fluentd、logstash。
• 在每个节点上运行监控 DaemonSet，例如 Prometheus Node Exporter、zabbix agent等
• 一个简单的用法是在所有的节点上都启动一个 DaemonSet，将被作为每种 类型的 daemon 使用。 • 一个稍微复杂的用法是单独对每种 daemon 类型使用多个 DaemonSet， 但具有不同的标志， 并且对不同硬件类型具有不同的内存、CPU 要求。
4.StatefulSet
StatefulSet 是用来管理有状态应用的工作负载 API 对象。实例之间有不对 等关系，以及实例对外部数据有依赖关系的应用，称为“有状态应用”
StatefulSet 用来管理 Deployment 和扩展一组 Pod，并且能为这些 Pod 提供序号和唯一性保证。
StatefulSets 对于需要满足以下一个或多个需求的应用程序很有价值：
• 稳定的、唯一的网络标识符。
• 稳定的、持久的存储。
• 有序的、优雅的部署和缩放。
• 有序的、自动的滚动更新。
5.Job
Job执行批处理任务，仅执行一次任务，保证任务的一个或多个Pod成功结束。
6.CronJob
Cron Job 创建基于时间调度的 Jobs。 一个 CronJob 对象就像 crontab (cron table) 文件中的一行，它用 Cron 格式进行编写，并周期性地在给定的调度时间执行 Job。
7.HPA
HPA根据资源利用率自动调整service中Pod数量，实现Pod水平自动缩放。
2. ReplicaSet控制器
[kubeadm@server1 mainfest]$ vim rs.yml
[kubeadm@server1 mainfest]$ cat rs.yml------------>replicationSet控制器的配置文件
apiVersion: apps/v1
kind: ReplicaSet -------------->这里是控制器种类，之前我们见到的是pod
metadata:
name: replicaset-example
spec:
replicas: 3
selector:
matchLabels:
app: myapp
template:
metadata:
labels:
app: myapp
spec:
containers:
- name: myapp
image: myapp:v1
[kubeadm@server1 mainfest]$ kubectl apply -f rs.yml
replicaset.apps/replicaset-example created
[kubeadm@server1 mainfest]$ kubectl get pod -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
replicaset-example-69tbm 1/1 Running 0 17s 10.244.1.31 server2 <none> <none>
replicaset-example-d46ff 1/1 Running 0 17s 10.244.2.44 server3 <none> <none>
replicaset-example-tmm25 1/1 Running 0 17s 10.244.2.45 server3 <none> <none>
[kubeadm@server1 mainfest]$ vim rs.yml
[kubeadm@server1 mainfest]$ cat rs.yml
apiVersion: apps/v1
kind: ReplicaSet
metadata:
name: replicaset-example
spec:
replicas: 10 ----------->这里指副本数，可以任意扩容或者缩容
selector:
matchLabels:
app: myapp
template:
metadata:
labels:
app: myapp
spec:
containers:
- name: myapp
image: myapp:v1
[kubeadm@server1 mainfest]$ kubectl apply -f rs.yml
replicaset.apps/replicaset-example configured
[kubeadm@server1 mainfest]$ kubectl get pod -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
replicaset-example-69tbm 1/1 Running 0 39s 10.244.1.31 server2 <none> <none>
replicaset-example-7zxcw 1/1 Running 0 4s 10.244.1.35 server2 <none> <none>
replicaset-example-94p7z 1/1 Running 0 4s 10.244.2.47 server3 <none> <none>
replicaset-example-d46ff 1/1 Running 0 39s 10.244.2.44 server3 <none> <none>
replicaset-example-f9vf9 1/1 Running 0 4s 10.244.1.33 server2 <none> <none>
replicaset-example-lbpls 1/1 Running 0 4s 10.244.2.48 server3 <none> <none>
replicaset-example-spt6f 1/1 Running 0 4s 10.244.1.32 server2 <none> <none>
replicaset-example-tfwjh 1/1 Running 0 4s 10.244.1.34 server2 <none> <none>
replicaset-example-tmm25 1/1 Running 0 39s 10.244.2.45 server3 <none> <none>
replicaset-example-vsl5k 1/1 Running 0 4s 10.244.2.46 server3 <none> <none>
[kubeadm@server1 mainfest]$ vim rs.yml
[kubeadm@server1 mainfest]$ cat rs.yml
apiVersion: apps/v1
kind: ReplicaSet
metadata:
name: replicaset-example
spec:
replicas: 2 ------------->这里再进行缩容
selector:
matchLabels:
app: myapp
template:
metadata:
labels:
app: myapp
spec:
containers:
- name: myapp
image: myapp:v1
[kubeadm@server1 mainfest]$ kubectl apply -f rs.yml
replicaset.apps/replicaset-example configured
[kubeadm@server1 mainfest]$ kubectl get pod -o wide ----------->回收的时候先回收新创建的容器
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
replicaset-example-69tbm 1/1 Running 0 57s 10.244.1.31 server2 <none> <none>
replicaset-example-7zxcw 0/1 Terminating 0 22s 10.244.1.35 server2 <none> <none>
replicaset-example-94p7z 0/1 Terminating 0 22s 10.244.2.47 server3 <none> <none>
replicaset-example-d46ff 0/1 Terminating 0 57s 10.244.2.44 server3 <none> <none>
replicaset-example-f9vf9 0/1 Terminating 0 22s 10.244.1.33 server2 <none> <none>
replicaset-example-lbpls 0/1 Terminating 0 22s 10.244.2.48 server3 <none> <none>
replicaset-example-spt6f 0/1 Terminating 0 22s 10.244.1.32 server2 <none> <none>
replicaset-example-tfwjh 0/1 Terminating 0 22s 10.244.1.34 server2 <none> <none>
replicaset-example-tmm25 1/1 Running 0 57s 10.244.2.45 server3 <none> <none>
replicaset-example-vsl5k 0/1 Terminating 0 22s 10.244.2.46 server3 <none> <none>
[kubeadm@server1 mainfest]$ kubectl get pod -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
replicaset-example-69tbm 1/1 Running 0 66s 10.244.1.31 server2 <none> <none>
replicaset-example-tmm25 1/1 Running 0 66s 10.244.2.45 server3 <none> <none>
[kubeadm@server1 mainfest]$ kubectl get all
NAME READY STATUS RESTARTS AGE
pod/replicaset-example-69tbm 1/1 Running 0 74s
pod/replicaset-example-tmm25 1/1 Running 0 74s
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
service/kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 7d
NAME DESIRED CURRENT READY AGE --------->出现新的控制器类型
replicaset.apps/replicaset-example 2 2 2 74s但如果在文件中修改镜像，则不会被满足
3.deployment控制器
3.1 单个deployment控制器
[kubeadm@server1 mainfest]$ vim deployment.yml
[kubeadm@server1 mainfest]$ cat deployment.yml
apiVersion: apps/v1
kind: Deployment --------->控制器名称
metadata:
name: deployment-myapp
spec:
replicas: 3
selector:
matchLabels:
app: myapp
template:
metadata:
labels:
app: myapp
spec:
containers:
- name: myapp
image: myapp:v1
ports:
- containerPort: 80
[kubeadm@server1 mainfest]$ kubectl apply -f deployment.yml
deployment.apps/deployment-myapp created
[kubeadm@server1 mainfest]$ kubectl get all
NAME READY STATUS RESTARTS AGE
pod/deployment-myapp-569fb7cdcb-4z2bp 1/1 Running 0 10s
deployment控制器------rs名字-----标识符
pod/deployment-myapp-569fb7cdcb-s7qv6 1/1 Running 0 10s
pod/deployment-myapp-569fb7cdcb-wrddw 1/1 Running 0 10s
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
service/kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 7d1h
NAME READY UP-TO-DATE AVAILABLE AGE
deployment.apps/deployment-myapp 3/3 3 3 10s
deployment控制器
NAME DESIRED CURRENT READY AGE
replicaset.apps/deployment-myapp-569fb7cdcb 3 3 3 10s
rs控制器注意：在deployment控制器中，如果删除pod后还会有新的pod的pod，所以如果pod状态不对可以删除进行调整。
3.2 多个deployment控制器
[kubeadm@server1 mainfest]$ vim deployment.yml
[kubeadm@server1 mainfest]$ cat deployment.yml
apiVersion: apps/v1 ------------------>控制器1号
kind: Deployment
metadata:
name: deployment-v1
spec:
replicas: 3
selector:
matchLabels:
app: myapp
template:
metadata:
labels:
app: myapp
spec:
containers:
- name: myapp
image: myapp:v1
ports:
- containerPort: 80
---
apiVersion: apps/v1 --------------------->控制器2号
kind: Deployment
metadata:
name: deployment-v2
spec:
replicas: 3
selector:
matchLabels:
app: myapp
template:
metadata:
labels:
app: myapp
spec:
containers:
- name: myapp
image: myapp:v2
ports:
- containerPort: 80
[kubeadm@server1 mainfest]$ kubectl apply -f deployment.yml
deployment.apps/deployment-v1 created
deployment.apps/deployment-v2 created
[kubeadm@server1 mainfest]$ kubectl get all
NAME READY STATUS RESTARTS AGE
pod/deployment-myapp-569fb7cdcb-2tnnl 1/1 Running 0 10m
pod/deployment-myapp-569fb7cdcb-9n92v 1/1 Running 0 10m
pod/deployment-myapp-569fb7cdcb-pzjwt 1/1 Running 0 10m
pod/deployment-v1-569fb7cdcb-bqtjj 1/1 Running 0 8s
pod/deployment-v1-569fb7cdcb-ctzp6 1/1 Running 0 8s
pod/deployment-v1-569fb7cdcb-xjnf4 1/1 Running 0 8s
pod/deployment-v2-6b54f6ffb9-lbbbx 1/1 Running 0 7s
pod/deployment-v2-6b54f6ffb9-q7fph 1/1 Running 0 8s
pod/deployment-v2-6b54f6ffb9-rvgzq 1/1 Running 0 7s
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
service/kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 7d1h
NAME READY UP-TO-DATE AVAILABLE AGE
deployment.apps/deployment-myapp 3/3 3 3 18m
deployment.apps/deployment-v1 3/3 3 3 8s
deployment.apps/deployment-v2 3/3 3 3 8s
NAME DESIRED CURRENT READY AGE
replicaset.apps/deployment-myapp-569fb7cdcb 3 3 3 18m
replicaset.apps/deployment-myapp-6b54f6ffb9 0 0 0 13m
replicaset.apps/deployment-v1-569fb7cdcb 3 3 3 8s
replicaset.apps/deployment-v2-6b54f6ffb9 3 3 3 8s
[kubeadm@server1 mainfest]$ kubectl delete deployments.apps deployment-v1 ##删除其中一个控制器4.DaemonSet控制器
DaemonSet控制器可以每个节点部署一个容器
[kubeadm@server1 mainfest]$ vim daemonset.yml
[kubeadm@server1 mainfest]$ cat daemonset.yml
apiVersion: apps/v1
kind: DaemonSet -------------->种类为DeamonSet控制器
metadata:
name: daemonset-example
labels:
k8s-app: zabbix-agent
spec:
selector:
matchLabels:
name: zabbix-agent
template:
metadata:
labels:
name: zabbix-agent
spec:
containers:
- name: zabbix-agent
image: zabbix-agent
[kubeadm@server1 mainfest]$ kubectl apply -f daemonset.yml
daemonset.apps/daemonset-example created
[kubeadm@server1 mainfest]$ kubectl get pod -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
daemonset-example-8n9mv 1/1 Running 0 8s 10.244.2.59 server3 <none> <none>
daemonset-example-zfprr 1/1 Running 0 8s 10.244.1.44 server2 <none> <none>5.Job控制器
[kubeadm@server1 mainfest]$ vim job.yml
[kubeadm@server1 mainfest]$ cat job.yml
apiVersion: batch/v1
kind: Job ------------>类型为Job的控制器
metadata:
name: pi
spec:
template:
metadata:
name: pi
spec:
containers:
- name: pi
image: perl
command: ["perl", "-Mbignum=bpi", "-wle", "print bpi(2000)"]
restartPolicy: Never
[kubeadm@server1 mainfest]$ kubectl apply -f job.yml
job.batch/pi created
[kubeadm@server1 mainfest]$ kubectl get pod
NAME READY STATUS RESTARTS AGE
pi-fzj8p 0/1 Completed 0 6s
[kubeadm@server1 mainfest]$ kubectl get pod -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
pi-fzj8p 0/1 Completed 0 12s 10.244.2.60 server3 <none> <none>
[kubeadm@server1 mainfest]$ kubectl logs pi-fzj8p --------->获取日志
3.14159265358979323846264338327950288419716939937510582097494459230781640628620899862803482534211706798214808651328230664709384460955058223172535940812848111745028410270193852110555964462294895493038196442881097566593344612847564823378678316527120190914564856692346034861045432664821339360726024914127372458700660631558817488152092096282925409171536436789259036001133053054882046652138414695194151160943305727036575959195309218611738193261179310511854807446237996274956735188575272489122793818301194912983367336244065664308602139494639522473719070217986094370277053921717629317675238467481846766940513200056812714526356082778577134275778960917363717872146844090122495343014654958537105079227968925892354201995611212902196086403441815981362977477130996051870721134999999837297804995105973173281609631859502445945534690830264252230825334468503526193118817101000313783875288658753320838142061717766914730359825349042875546873115956286388235378759375195778185778053217122680661300192787661119590921642019893809525720106548586327886593615338182796823030195203530185296899577362259941389124972177528347913151557485724245415069595082953311686172785588907509838175463746493931925506040092770167113900984882401285836160356370766010471018194295559619894676783744944825537977472684710404753464620804668425906949129331367702898915210475216205696602405803815019351125338243003558764024749647326391419927260426992279678235478163600934172164121992458631503028618297455570674983850549458858692699569092721079750930295532116534498720275596023648066549911988183479775356636980742654252786255181841757467289097777279380008164706001614524919217321721477235014144197356854816136115735255213347574184946843852332390739414333454776241686251898356948556209921922218427255025425688767179049460165346680498862723279178608578438382796797668145410095388378636095068006422512520511739298489608412848862694560424196528502221066118630674427862203919494504712371378696095636437191728746776465757396241389086583264599581339047802759016. CronJob 控制器
[kubeadm@server1 mainfest]$ vim cronjob.yml
[kubeadm@server1 mainfest]$ cat cronjob.yml
apiVersion: batch/v1beta1
kind: CronJob ------------->给予时间按时调度的Job控制器
metadata:
name: cronjob-example
spec:
schedule: "* * * * *" ------------->每分钟一次
jobTemplate:
spec:
template:
spec:
containers:
- name: cronjob
image: busybox
args:
- /bin/sh
- -c
- date; echo Hello from k8s cluster
restartPolicy: OnFailure
[kubeadm@server1 mainfest]$ kubectl apply -f cronjob.yml
cronjob.batch/cronjob-example created
[kubeadm@server1 mainfest]$ kubectl get pod
No resources found in default namespace.
[kubeadm@server1 mainfest]$ kubectl get pod
NAME READY STATUS RESTARTS AGE
cronjob-example-1593121920-sv47j 0/1 Completed 0 54s
[kubeadm@server1 mainfest]$ kubectl get pod
NAME READY STATUS RESTARTS AGE
cronjob-example-1593121920-sv47j 0/1 Completed 0 65s
cronjob-example-1593121980-pxjvs 0/1 ContainerCreating 0 5s
[kubeadm@server1 mainfest]$ kubectl logs cronjob-example-1593121920-sv47j
Thu Jun 25 21:52:39 UTC 2020
Hello from k8s cluster
[kubeadm@server1 mainfest]$ kubectl logs cronjob-example-1593121980-pxjvs
Thu Jun 25 21:53:13 UTC 2020
Hello from k8s clusterService
Service介绍
Service可以看作是一组提供相同服务的Pod对外的访问接口。借助Service，应用可以方便地实现服务发现和负载均衡。 service默认只支持4层负载均衡能力，没有7层功能。（可以通过Ingress实现）
service的类型：
• ClusterIP：默认值，k8s系统给service自动分配的虚拟IP，只能在集群内部访问。
• NodePort：将Service通过指定的Node上的端口暴露给外部，访问任意一个 NodeIP:nodePort都将路由到ClusterIP。
• LoadBalancer：在 NodePort 的基础上，借助 cloud provider 创建一个外部的负 载均衡器，并将请求转发到 :NodePort，此模式只能在云服务器上使用。
• ExternalName：将服务通过 DNS CNAME 记录方式转发到指定的域名（通过 spec.externlName 设定）。
Service 是由 kube-proxy 组件，加上 iptables 来共同实现的.
• kube-proxy 通过 iptables 处理 Service 的过程，需要在宿主机上设置相当多的 iptables 规则，如果宿主机有大量的Pod，不断刷新iptables规则，会消耗大量的 CPU资源。
• IPVS模式的service，可以使K8s集群支持更多量级的Pod。
开启kube-proxy的ipvs模式
开启kube-proxy的ipvs模式：
yum install -y ipvsadm 所有节点安装
kubectl edit cm kube-proxy -n kube-system 修改IPVS模式 mode: “ipvs”
kubectl get pod -n kube-system |grep kube-proxy | awk '{system("kubectl delete pod "$1" -n kube-system")}'更新kube-proxy pod
IPVS模式下，kube-proxy会在service创建后，在宿主机上添加一个虚拟网卡： kube-ipvs0，并分配service IP。
kube-proxy通过linux的IPVS模块，以rr轮询方式调度service中的Pod。
创建service
ClusterIP
Kubernetes 提供了一个 DNS 插件 Service
[kubeadm@server1 mainfest]$ vim service.yml
[kubeadm@server1 mainfest]$ cat service.yml
kind: Service ------------------>创建service，默认类型是ClusterIP
apiVersion: v1
metadata:
name: myservice
spec:
ports:
- protocol: TCP
port: 80
targetPort: 80
selector:
app: myapp
[kubeadm@server1 mainfest]$ kubectl apply -f service.yml
service/myservice created
[kubeadm@server1 mainfest]$ vim pod2.yml
[kubeadm@server1 mainfest]$ cat pod2.yml
apiVersion: apps/v1
kind: Deployment
metadata:
name: deployment-example
spec:
replicas: 2
selector:
matchLabels:
app: myapp
template:
metadata:
labels:
app: myapp
spec:
containers:
- name: myapp
image: myapp:v2
[kubeadm@server1 mainfest]$ kubectl apply -f pod2.yml
deployment.apps/deployment-example created
[kubeadm@server1 mainfest]$ kubectl describe svc myservice
Name: myservice
Namespace: default
Labels: <none>
Annotations: Selector: app=myapp
Type: ClusterIP
IP: 10.107.6.65
Port: <unset> 80/TCP
TargetPort: 80/TCP
Endpoints: 10.244.1.47:80,10.244.2.70:80
Session Affinity: None
Events: <none>
[kubeadm@server1 mainfest]$ kubectl run demo --image=busyboxplus -it --restart=Never
If you don't see a command prompt, try pressing enter.
[ root@demo:/ ]$ curl 10.107.6.65
Hello MyApp | Version: v2 | <a href="hostname.html">Pod Name</a>
[ root@demo:/ ]$ curl 10.107.6.65
Hello MyApp | Version: v2 | <a href="hostname.html">Pod Name</a>
[ root@demo:/ ]$ curl 10.107.6.65/hostname.html
deployment-example-67764dd8bd-pvkc6
[ root@demo:/ ]$ curl 10.107.6.65/hostname.html
deployment-example-67764dd8bd-p5qnr
[ root@demo:/ ]$ curl 10.107.6.65/hostname.html
deployment-example-67764dd8bd-pvkc6
[ root@demo:/ ]$ curl 10.107.6.65/hostname.html
deployment-example-67764dd8bd-p5qnr
[ root@demo:/ ]$ curl myservice/hostname.html-------------->可以通过域名访问
deployment-example-67764dd8bd-pvkc6
[ root@demo:/ ]$ curl myservice/hostname.html
deployment-example-67764dd8bd-p5qnr
[ root@demo:/ ]$ curl myservice/hostname.html
deployment-example-67764dd8bd-pvkc6
[ root@demo:/ ]$ nslookup myservice
Server: 10.96.0.10
Address 1: 10.96.0.10 kube-dns.kube-system.svc.cluster.local
Name: myservice
Address 1: 10.107.6.65 myservice.default.svc.cluster.local
[ root@demo:/ ]$ [kubeadm@server1 mainfest]$
[kubeadm@server1 mainfest]$ kubectl get services kube-dns --namespace=kube-system
k8s提供了一个DNS插件Service
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kube-dns ClusterIP 10.96.0.10 <none> 53/UDP,53/TCP,9153/TCP 7d3hNodePort（可外部访问）
[kubeadm@server1 mainfest]$ cat pod2.yml
apiVersion: apps/v1
kind: Deployment
metadata:
name: deployment-example
spec:
replicas: 2
selector:
matchLabels:
app: myapp
template:
metadata:
labels:
app: myapp
spec:
containers:
- name: myapp
image: myapp:v2
[kubeadm@server1 mainfest]$ kubectl apply -f pod2.yml
deployment.apps/deployment-example unchanged
[kubeadm@server1 mainfest]$ kubectl get pod
NAME READY STATUS RESTARTS AGE
demo 0/1 Completed 0 7h16m
deployment-example-67764dd8bd-p5qnr 1/1 Running 0 7h17m
deployment-example-67764dd8bd-pvkc6 1/1 Running 0 7h17m
[kubeadm@server1 mainfest]$ vim service.yml
[kubeadm@server1 mainfest]$ cat service.yml
kind: Service
apiVersion: v1
metadata:
name: myservice
spec:
ports:
- protocol: TCP
port: 80
targetPort: 80
selector:
app: myapp
[kubeadm@server1 mainfest]$ kubectl apply -f service.yml
service/myservice created
[kubeadm@server1 mainfest]$ kubectl get svc
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 7d10h
myservice ClusterIP 10.100.83.68 <none> 80/TCP 5s
[kubeadm@server1 mainfest]$ kubectl edit svc myservice ------>修改为NodePort方式
service/myservice edited
[kubeadm@server1 mainfest]$ kubectl describe svc myservice
Name: myservice
Namespace: default
Labels: <none>
Annotations: Selector: app=myapp
Type: NodePort
IP: 10.100.83.68
Port: <unset> 80/TCP
TargetPort: 80/TCP
NodePort: <unset> 31059/TCP
Endpoints: 10.244.1.47:80,10.244.2.70:80
Session Affinity: None
External Traffic Policy: Cluster
Events: <none>
[kubeadm@server1 mainfest]$ kubectl get svc
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 7d10h
myservice NodePort 10.100.83.68 <none> 80:31059/TCP 5m30s -------->每个节点会随机开一个端口无头服务
Headless Service “无头服务” 。 Headless Service不需要分配一个VIP，而是直接以DNS记录的方式解析出被代理 Pod的IP地址。
域名格式：$(servicename).$(namespace).svc.cluster.local
yum install -y bind-utils.x86_64安装解析工具
[kubeadm@server1 mainfest]$ vim service.yml
[kubeadm@server1 mainfest]$ cat service.yml
kind: Service
apiVersion: v1
metadata:
name: myservice
spec:
ports:
- protocol: TCP
port: 80
targetPort: 80
selector:
app: myapp
clusterIP: None -------------->无头服务，不分配IP
[kubeadm@server1 mainfest]$ kubectl apply -f service.yml
service/myservice created
[kubeadm@server1 mainfest]$ kubectl get svc
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 7d11h
myservice ClusterIP None <none> 80/TCP 10s
[kubeadm@server1 mainfest]$ kubectl describe svc myservice
Name: myservice
Namespace: default
Labels: <none>
Annotations: Selector: app=myapp
Type: ClusterIP
IP: None --------------------->无头服务，不分配IP
Port: <unset> 80/TCP
TargetPort: 80/TCP
Endpoints: 10.244.1.47:80,10.244.1.48:80,10.244.2.70:80
Session Affinity: None
Events: <none>
[kubeadm@server1 mainfest]$ kubectl -n kube-system describe svc kube-dns
Name: kube-dns
Namespace: kube-system
Labels: k8s-app=kube-dns
kubernetes.io/cluster-service=true
kubernetes.io/name=KubeDNS
Annotations: prometheus.io/port: 9153
prometheus.io/scrape: true
Selector: k8s-app=kube-dns
Type: ClusterIP
IP: 10.96.0.10
Port: dns 53/UDP
TargetPort: 53/UDP
Endpoints: 10.244.0.10:53,10.244.0.11:53
Port: dns-tcp 53/TCP
TargetPort: 53/TCP
Endpoints: 10.244.0.10:53,10.244.0.11:53 ----------->给集群分配的IP
Port: metrics 9153/TCP
TargetPort: 9153/TCP
Endpoints: 10.244.0.10:9153,10.244.0.11:9153
Session Affinity: None
Events: <none>
[kubeadm@server1 mainfest]$ dig myservice.default.svc.cluster.local @10.96.0.10 -------------->两个IP都可以解析到
; <<>> DiG 9.9.4-RedHat-9.9.4-72.el7 <<>> myservice.default.svc.cluster.local @10.96.0.10
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 19011
;; flags: qr aa rd; QUERY: 1, ANSWER: 3, AUTHORITY: 0, ADDITIONAL: 1
;; WARNING: recursion requested but not available
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;myservice.default.svc.cluster.local. IN A
;; ANSWER SECTION:
myservice.default.svc.cluster.local. 30 IN A 10.244.2.70
myservice.default.svc.cluster.local. 30 IN A 10.244.1.48
myservice.default.svc.cluster.local. 30 IN A 10.244.1.47
;; Query time: 0 msec
;; SERVER: 10.96.0.10#53(10.96.0.10)
;; WHEN: Fri Jun 26 15:01:23 CST 2020
;; MSG SIZE rcvd: 217
[kubeadm@server1 mainfest]$ dig myservice.default.svc.cluster.local @10.244.0.11
; <<>> DiG 9.9.4-RedHat-9.9.4-72.el7 <<>> myservice.default.svc.cluster.local @10.244.0.11
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 16525
;; flags: qr aa rd; QUERY: 1, ANSWER: 3, AUTHORITY: 0, ADDITIONAL: 1
;; WARNING: recursion requested but not available
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;myservice.default.svc.cluster.local. IN A
;; ANSWER SECTION:
myservice.default.svc.cluster.local. 30 IN A 10.244.1.48
myservice.default.svc.cluster.local. 30 IN A 10.244.2.70
myservice.default.svc.cluster.local. 30 IN A 10.244.1.47 --------------->还可实现轮询
;; Query time: 0 msec
;; SERVER: 10.244.0.11#53(10.244.0.11)
;; WHEN: Fri Jun 26 15:02:57 CST 2020
;; MSG SIZE rcvd: 217Pod滚动更新后，依然可以解析：
[kubeadm@server1 mainfest]$ kubectl delete pod --all
pod "deployment-example-67764dd8bd-p5qnr" deleted
pod "deployment-example-67764dd8bd-pvkc6" deleted
pod "deployment-example-67764dd8bd-smr7c" deleted
[kubeadm@server1 mainfest]$ kubectl get pod -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
deployment-example-67764dd8bd-6pwdw 1/1 Running 0 7s 10.244.2.74 server3 <none> <none>
deployment-example-67764dd8bd-jl7nl 1/1 Running 0 7s 10.244.1.49 server2 <none> <none>
deployment-example-67764dd8bd-zvd28 1/1 Running 0 7s 10.244.2.73 server3 <none> <none>
[kubeadm@server1 mainfest]$ dig myservice.default.svc.cluster.local @10.244.0.11 ------------>Pod滚动更新以后，依然可以解析
; <<>> DiG 9.9.4-RedHat-9.9.4-72.el7 <<>> myservice.default.svc.cluster.local @10.244.0.11
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 48989
;; flags: qr aa rd; QUERY: 1, ANSWER: 3, AUTHORITY: 0, ADDITIONAL: 1
;; WARNING: recursion requested but not available
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;myservice.default.svc.cluster.local. IN A
;; ANSWER SECTION:
myservice.default.svc.cluster.local. 30 IN A 10.244.1.49
myservice.default.svc.cluster.local. 30 IN A 10.244.2.73
myservice.default.svc.cluster.local. 30 IN A 10.244.2.74
;; Query time: 0 msec
;; SERVER: 10.244.0.11#53(10.244.0.11)
;; WHEN: Fri Jun 26 15:14:37 CST 2020
;; MSG SIZE rcvd: 217LoadBalancer（可外部访问）
从外部访问 Service 的第二种方式，适用于公有云上的 Kubernetes 服务。这时候，你可以指定一个 LoadBalancer 类型的 Service。
在service提交后，Kubernetes就会调用 CloudProvider 在公有云上创建一个负载均衡服务，并且把被代理的 Pod 的 IP地址配置给负载均衡服务做后端。
[kubeadm@server1 mainfest]$ vim service.yml
[kubeadm@server1 mainfest]$ cat service.yml
kind: Service
apiVersion: v1
metadata:
name: myservice
spec:
ports:
- protocol: TCP
port: 80
targetPort: 80
selector:
app: myapp
type: LoadBalancer ------------------>这里的类型为LoasBalancer
[kubeadm@server1 mainfest]$ kubectl apply -f service.yml
service/myservice created
[kubeadm@server1 mainfest]$ kubectl get svc
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 7d11h
myservice LoadBalancer 10.104.173.144 <pending> 80:32646/TCP 5s
需要访问公有云ExternalName（可外部访问）
从外部访问的第三种方式叫做ExternalName。适用于集群内部容器访问外部资源
[kubeadm@server1 mainfest]$ vim service.yml
[kubeadm@server1 mainfest]$ cat service.yml
kind: Service
apiVersion: v1
metadata:
name: myservice
spec:
ports:
- protocol: TCP
port: 80
targetPort: 80
selector:
app: myapp
type: ExternalName
externalName: www.baidu.com ---------->需要访问的外部域名
[kubeadm@server1 mainfest]$ kubectl apply -f service.yml
service/myservice created
[kubeadm@server1 mainfest]$ kubectl get svc
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 7d11h
myservice ExternalName <none> www.baidu.com 80/TCP 4s
[kubeadm@server1 mainfest]$ dig myservice.default.svc.cluster.local @10.244.0.11
; <<>> DiG 9.9.4-RedHat-9.9.4-72.el7 <<>> myservice.default.svc.cluster.local @10.244.0.11
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 44555
;; flags: qr aa rd; QUERY: 1, ANSWER: 4, AUTHORITY: 0, ADDITIONAL: 1
;; WARNING: recursion requested but not available
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;myservice.default.svc.cluster.local. IN A
;; ANSWER SECTION:
myservice.default.svc.cluster.local. 30 IN CNAME www.baidu.com. ----------->访问成功
www.baidu.com. 30 IN CNAME www.a.shifen.com.
www.a.shifen.com. 30 IN A 61.135.169.121
www.a.shifen.com. 30 IN A 61.135.169.125
;; Query time: 75 msec
;; SERVER: 10.244.0.11#53(10.244.0.11)
;; WHEN: Fri Jun 26 15:28:43 CST 2020
;; MSG SIZE rcvd: 233service直接分配一个公有IP（外网地址）
[kubeadm@server1 mainfest]$ vim service.yml
[kubeadm@server1 mainfest]$ cat service.yml
kind: Service
apiVersion: v1
metadata:
name: myservice
spec:
ports:
- protocol: TCP
port: 80
targetPort: 80
selector:
app: myapp
externalIPs: -------------->直接分配一个共有IP
- 172.25.1.100
[kubeadm@server1 mainfest]$ kubectl apply -f service.yml
service/myservice created
[kubeadm@server1 mainfest]$ kubectl get svc
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 7d11h
myservice ClusterIP 10.105.122.218 172.25.1.100 80/TCP 4s
[kubeadm@server1 mainfest]$ ip addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
valid_lft forever preferred_lft forever
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
link/ether 00:0c:29:bb:3e:1d brd ff:ff:ff:ff:ff:ff
inet 192.168.43.11/24 brd 192.168.43.255 scope global ens33
valid_lft forever preferred_lft forever
inet 172.25.1.1/24 brd 172.25.1.255 scope global ens33
valid_lft forever preferred_lft forever
inet 192.168.3.201/24 brd 192.168.3.255 scope global ens33
valid_lft forever preferred_lft forever
inet6 2408:84fb:1:1209:20c:29ff:febb:3e1d/64 scope global mngtmpaddr dynamic
valid_lft 3317sec preferred_lft 3317sec
inet6 fe80::20c:29ff:febb:3e1d/64 scope link
valid_lft forever preferred_lft forever
3: docker0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN group default
link/ether 02:42:da:68:ae:81 brd ff:ff:ff:ff:ff:ff
inet 172.17.0.1/16 brd 172.17.255.255 scope global docker0
valid_lft forever preferred_lft forever
4: flannel.1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1450 qdisc noqueue state UNKNOWN group default
link/ether d2:fd:d6:3b:73:d3 brd ff:ff:ff:ff:ff:ff
inet 10.244.0.0/32 scope global flannel.1
valid_lft forever preferred_lft forever
inet6 fe80::d0fd:d6ff:fe3b:73d3/64 scope link
valid_lft forever preferred_lft forever
5: cni0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1450 qdisc noqueue state UP group default qlen 1000
link/ether 4a:a1:c4:bb:75:78 brd ff:ff:ff:ff:ff:ff
inet 10.244.0.1/24 scope global cni0
valid_lft forever preferred_lft forever
inet6 fe80::48a1:c4ff:febb:7578/64 scope link
valid_lft forever preferred_lft forever
6: veth3fc18a62@if3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1450 qdisc noqueue master cni0 state UP group default
link/ether a2:7d:16:36:60:6a brd ff:ff:ff:ff:ff:ff link-netnsid 0
inet6 fe80::a07d:16ff:fe36:606a/64 scope link
valid_lft forever preferred_lft forever
7: veth99a251bf@if3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1450 qdisc noqueue master cni0 state UP group default
link/ether 86:20:80:1b:26:22 brd ff:ff:ff:ff:ff:ff link-netnsid 1
inet6 fe80::8420:80ff:fe1b:2622/64 scope link
valid_lft forever preferred_lft forever
8: dummy0: <BROADCAST,NOARP> mtu 1500 qdisc noop state DOWN group default qlen 1000
link/ether d2:d9:2f:45:a0:05 brd ff:ff:ff:ff:ff:ff
9: kube-ipvs0: <BROADCAST,NOARP> mtu 1500 qdisc noop state DOWN group default
link/ether 9a:26:f3:9b:57:38 brd ff:ff:ff:ff:ff:ff
inet 10.96.0.1/32 brd 10.96.0.1 scope global kube-ipvs0
valid_lft forever preferred_lft forever
inet 10.96.0.10/32 brd 10.96.0.10 scope global kube-ipvs0
valid_lft forever preferred_lft forever
inet 10.105.122.218/32 brd 10.105.122.218 scope global kube-ipvs0
valid_lft forever preferred_lft forever
inet 172.25.1.100/32 brd 172.25.1.100 scope global kube-ipvs0 -------------------->在这里
valid_lft forever preferred_lft forever
[kubeadm@server1 mainfest]$ logout
[root@server1 ~]# ipvsadm -ln
IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
-> RemoteAddress:Port Forward Weight ActiveConn InActConn
TCP 172.25.1.100:80 rr
-> 10.244.1.49:80 Masq 1 0 0
-> 10.244.2.73:80 Masq 1 0 0
-> 10.244.2.74:80 Masq 1 0 0
TCP 10.96.0.1:443 rr
-> 192.168.43.11:6443 Masq 1 0 0
TCP 10.96.0.10:53 rr
-> 10.244.0.10:53 Masq 1 0 0
-> 10.244.0.11:53 Masq 1 0 0
TCP 10.96.0.10:9153 rr
-> 10.244.0.10:9153 Masq 1 0 0
-> 10.244.0.11:9153 Masq 1 0 0
TCP 10.105.122.218:80 rr
-> 10.244.1.49:80 Masq 1 0 0
-> 10.244.2.73:80 Masq 1 0 0
-> 10.244.2.74:80 Masq 1 0 0
UDP 10.96.0.10:53 rr
-> 10.244.0.10:53 Masq 1 0 0
-> 10.244.0.11:53 Masq 1 0 0