[machangwei@mcwk8s-master ~]$ cat mcwHttpd.yml
kind: Deployment
metadata:
name: mcw-httpd
spec:
replicas: 3
selector:
matchLabels:
run: mcw-httpd
template:
metadata:
labels:
run: mcw-httpd
spec:
containers:
- name: mcw-httpd
image: httpd
ports:
- containerPort: 80
[machangwei@mcwk8s-master ~]$ kubectl apply -f mcwHttpd.yml
deployment.apps/mcw-httpd created
[machangwei@mcwk8s-master ~]$ kubectl get pod -o wide
NAME                         READY   STATUS              RESTARTS   AGE     IP            NODE           NOMINATED NODE   READINESS GATES
mcw-httpd-6fbf67d7d5-5rrkh   0/1     ContainerCreating   0          2m52s           mcwk8s-node1              
mcw-httpd-6fbf67d7d5-bqq58   0/1     ImagePullBackOff    0          2m52s   10.244.0.78   mcwk8s-node2              
mcw-httpd-6fbf67d7d5-j52ff   0/1     ImagePullBackOff    0          2m52s   10.244.0.70   mcwk8s-node1              
[machangwei@mcwk8s-master ~]$ kubectl get pod -o wide #过一会后，查看Pod分配了各自的IP，容器在创建的时候ip是none
NAME                         READY   STATUS    RESTARTS   AGE     IP            NODE           NOMINATED NODE   READINESS GATES
mcw-httpd-6fbf67d7d5-5rrkh   1/1     Running   0          6m28s   10.244.0.71   mcwk8s-node1              
mcw-httpd-6fbf67d7d5-bqq58   1/1     Running   0          6m28s   10.244.0.78   mcwk8s-node2              
mcw-httpd-6fbf67d7d5-j52ff   1/1     Running   0          6m28s   10.244.0.70   mcwk8s-node1              
[machangwei@mcwk8s-master ~]$ #这些ip只能被kubernates Cluster中的容器和节点访问

[machangwei@mcwk8s-master ~]$ kubectl get pod -o wide
NAME                         READY   STATUS    RESTARTS   AGE   IP            NODE           NOMINATED NODE   READINESS GATES
mcw-httpd-6fbf67d7d5-5rrkh   1/1     Running   0          16m   10.244.0.71   mcwk8s-node1              
mcw-httpd-6fbf67d7d5-bqq58   1/1     Running   0          16m   10.244.0.78   mcwk8s-node2              
mcw-httpd-6fbf67d7d5-j52ff   1/1     Running   0          16m   10.244.0.70   mcwk8s-node1              
[machangwei@mcwk8s-master ~]$ curl 10.244.0.78 #主节点访问节点2上的pod的ip，连接超时
curl: (7) Failed connect to 10.244.0.78:80; Connection timed out

节点2上访问节点2上的pod ip是能访问的
[root@mcwk8s-node2 ~]$ curl 10.244.0.78
It works!

怀疑是节点上flannel状态问题
[machangwei@mcwk8s-master ~]$ kubectl get pod --all-namespaces|grep flannel
kube-system   kube-flannel-ds-cn4m9                   0/1     Error              233 (5m26s ago)   2d11h
kube-system   kube-flannel-ds-hpgkz                   1/1     Running            0                 6d23h
kube-system   kube-flannel-ds-nnjvj                   0/1     CrashLoopBackOff   271 (15s ago)     6d23h

怀疑节点2上没添加-H的问题，然后添加重启docker daemon ，四个容器都重启了
[root@mcwk8s-node2 ~]$ vim /usr/lib/systemd/system/docker.service
[root@mcwk8s-node2 ~]$ grep -i execstart /usr/lib/systemd/system/docker.service
ExecStart=/usr/bin/dockerd -H fd:// -H tcp://0.0.0.0 --containerd=/run/containerd/containerd.sock
[root@mcwk8s-node2 ~]$ systemctl daemon-reload
[root@mcwk8s-node2 ~]$ systemctl restart docker
[root@mcwk8s-node2 ~]$ docker ps
CONTAINER ID   IMAGE                                               COMMAND                  CREATED         STATUS         PORTS     NAMES
88de5020b420   registry.aliyuncs.com/google_containers/pause:3.6   "/pause"                 1 second ago    Up 1 second              k8s_POD_kube-flannel-ds-cn4m9_kube-system_ef070440-6778-430f-92b9-a1c48b755d2b_1
adf80a28c0be   b46c42588d51                                        "/usr/local/bin/kube…"   2 seconds ago   Up 1 second              k8s_kube-proxy_kube-proxy-92g5c_kube-system_a69acf11-f51a-46d6-9472-d54b5383efef_1
46bceff879bd   registry.aliyuncs.com/google_containers/pause:3.6   "/pause"                 6 seconds ago   Up 2 seconds             k8s_POD_kube-proxy-92g5c_kube-system_a69acf11-f51a-46d6-9472-d54b5383efef_1
a5cdf7f6ef3b   registry.aliyuncs.com/google_containers/pause:3.6   "/pause"                 6 seconds ago   Up 2 seconds             k8s_POD_mcw-httpd-6fbf67d7d5-bqq58_default_4ceffe1e-df14-47dd-82f0-83cb68555de7_1

再次在主节点访问节点2上的pod ip ,还是无法访问，由于节点2上pod重启了，所以ip被重新分配了一个
[machangwei@mcwk8s-master ~]$ kubectl get pod -o wide
NAME                         READY   STATUS    RESTARTS      AGE   IP            NODE           NOMINATED NODE   READINESS GATES
mcw-httpd-6fbf67d7d5-5rrkh   1/1     Running   0             30m   10.244.0.71   mcwk8s-node1              
mcw-httpd-6fbf67d7d5-bqq58   1/1     Running   1 (95s ago)   30m   10.244.0.79   mcwk8s-node2              
mcw-httpd-6fbf67d7d5-j52ff   1/1     Running   0             30m   10.244.0.70   mcwk8s-node1              
[machangwei@mcwk8s-master ~]$
[machangwei@mcwk8s-master ~]$
[machangwei@mcwk8s-master ~]$ curl 10.244.0.79 #虽然重新分配了ip，但是还是无法访问
curl: (7) Failed connect to 10.244.0.79:80; Connection timed out

[machangwei@mcwk8s-master ~]$ cat mcwHttpdService.yml
apiVersion: v1
kind: Service
metadata:
name: httpd-svc
spec:
selector:
run: httpd
ports:
- protocol: TCP
port: 8080
targetPort: 80
[machangwei@mcwk8s-master ~]$ kubectl apply -f mcwHttpdService.yml
service/httpd-svc created
[machangwei@mcwk8s-master ~]$ kubectl get service
NAME         TYPE        CLUSTER-IP    EXTERNAL-IP   PORT(S)    AGE
httpd-svc    ClusterIP   10.99.77.45           8080/TCP   14s
kubernetes   ClusterIP   10.96.0.1             443/TCP    7d
[machangwei@mcwk8s-master ~]$ curl 10.99.77.45:8080
curl: (7) Failed connect to 10.99.77.45:8080; Connection refused

[machangwei@mcwk8s-master ~]$ kubectl get deployment --namespace=kube-system
NAME      READY   UP-TO-DATE   AVAILABLE   AGE
coredns   2/2     2            2           7d1h
[machangwei@mcwk8s-master ~]$ kubectl get service -o wide
NAME         TYPE        CLUSTER-IP    EXTERNAL-IP   PORT(S)    AGE    SELECTOR
httpd-svc    ClusterIP   10.99.77.45           8080/TCP   61m    run=httpd
kubernetes   ClusterIP   10.96.0.1             443/TCP    7d1h   
[machangwei@mcwk8s-master ~]$ kubectl run mcwbusybox --rm -ti --image=busybox /bin/bash
pod "mcwbusybox" deleted
error: timed out waiting for the condition
[machangwei@mcwk8s-master ~]$ kubectl get pod
NAME                         READY   STATUS    RESTARTS      AGE
mcw-httpd-6fbf67d7d5-5rrkh   1/1     Running   0             124m
mcw-httpd-6fbf67d7d5-bqq58   1/1     Running   1 (95m ago)   124m
mcw-httpd-6fbf67d7d5-j52ff   1/1     Running   0             124m

只可以访问自己节点上的pod，不能跨主机同命名空间内的pod互相通信。不知道哪里的问题
[machangwei@mcwk8s-master ~]$ kubectl run mcwcentos3  -it --image=centos /bin/bash
If you don't see a command prompt, try pressing enter.
[root@mcwcentos3 /]# curl 10.244.0.79
curl: (7) Failed to connect to 10.244.0.79 port 80: Connection timed out
[root@mcwcentos3 /]# curl 10.244.0.70
It works!

[root@mcwcentos3 /]# curl 10.244.0.71
It works!

route add -host 10.244.0.0 dev flannel.1
flannel.1

NMI watchdog: BUG: soft lockup - CPU#0 stuck for 22s
报错现象 系统或者网络占用过多CPU,造成内核软死锁(soft lockup)。Soft lockup名称解释:所谓,soft lockup就是说,这个bug没有让系统彻底死机,但是若干个进程(或...

两个节点上的fannel状态不对
[machangwei@mcwk8s-master ~]$ kubectl get pod --all-namespaces -o wide|grep flannel
kube-system   kube-flannel-ds-cn4m9   0/1     CrashLoopBackOff   286 (3m50s ago)   3d10h   10.0.0.6      mcwk8s-node2               
kube-system   kube-flannel-ds-hpgkz    1/1     Running            1 (22h ago)       7d22h   10.0.0.4      mcwk8s-master              
kube-system   kube-flannel-ds-nnjvj    0/1     CrashLoopBackOff   325 (3m21s ago)   7d22h   10.0.0.5      mcwk8s-node1               
[machangwei@mcwk8s-master ~]

节点上查看对应容器的日志错误信，未成功注册cidr
[root@mcwk8s-node2 ~]$ docker ps -a|grep flannel
2252229253e3   e6ea68648f0c   "/opt/bin/flanneld -…"   10 seconds ago   Exited (1) 2 seconds ago              k8s_kube-flannel_kube-flannel-ds-cn4m9_kube-system_ef070440-6778-430f-92b9-a1c48b755d2b_284
[root@mcwk8s-node2 ~]$ docker logs 225
E0120 13:40:49.244765       1 main.go:325] Error registering network: failed to acquire lease: node "mcwk8s-node2" pod cidr not assigned
W0120 13:40:49.245111       1 reflector.go:424] github.com/flannel-io/flannel/subnet/kube/kube.go:379: watch of *v1.Node ended with: an error on the server ("unable to decode an event from the watch stream: context canceled") has prevented the request from succeeding

master初始化写进来的cidr
[root@mcwk8s-master ~]$ grep cidr  /etc/kubernetes/manifests/kube-controller-manager.yaml
- --allocate-node-cidrs=true
- --cluster-cidr=10.244.0.0/24

部署fannel用的网络
[machangwei@mcwk8s-master ~]$ grep -C 3 '"Network"' mm.yml
}
net-conf.json: |
{
"Network": "10.244.0.0/16",
"Backend": {
"Type": "vxlan"
}

修改网络
[machangwei@mcwk8s-master ~]$ vim mm.yml
[machangwei@mcwk8s-master ~]$ grep -C 3 '"Network"' mm.yml
}
net-conf.json: |
{
"Network": "10.244.0.0/24",
"Backend": {
"Type": "vxlan"
}
[machangwei@mcwk8s-master ~]      

修改网络后还是不行。直接从头部署k8s就好了，把flannel网络和初始化master都设置为10.244.0.0/16 网络

[machangwei@mcwk8s-master ~]$ kubectl get pod --all-namespaces
NAMESPACE     NAME                                    READY   STATUS    RESTARTS        AGE
kube-system   coredns-6d8c4cb4d-vctxx                 1/1     Running   1 (5m57s ago)   33m
kube-system   coredns-6d8c4cb4d-xkv9h                 1/1     Running   0               33m
kube-system   etcd-mcwk8s-master                      1/1     Running   0               33m
kube-system   kube-apiserver-mcwk8s-master            1/1     Running   1 (4m42s ago)   33m
kube-system   kube-controller-manager-mcwk8s-master   1/1     Running   1               33m
kube-system   kube-flannel-ds-fvwgm                   1/1     Running   0               22m
kube-system   kube-flannel-ds-l5fdg                   1/1     Running   0               25m
kube-system   kube-flannel-ds-mzdcw                   1/1     Running   0               21m
kube-system   kube-proxy-796l7                        1/1     Running   0               21m
kube-system   kube-proxy-8wtxn                        1/1     Running   0               22m
kube-system   kube-proxy-qr6b8                        1/1     Running   0               33m
kube-system   kube-scheduler-mcwk8s-master            1/1     Running   1               33m
[machangwei@mcwk8s-master ~]$ 

[machangwei@mcwk8s-master ~]$ kubectl get nodes
NAME            STATUS   ROLES                  AGE   VERSION
mcwk8s-master   Ready    control-plane,master   35m   v1.23.1
mcwk8s-node1    Ready                     23m   v1.23.1
mcwk8s-node2    Ready                     22m   v1.23.1

跟之前相比，很明显的是多了路由了。之前应该是节点网络没好，所以路由也不全

主节点
[root@mcwk8s-master ~]$ ip a
1: lo:  mtu 65536 qdisc noqueue state UNKNOWN qlen 1
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:  mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 00:0c:29:a2:3a:b7 brd ff:ff:ff:ff:ff:ff
inet 10.0.0.4/24 brd 10.0.0.255 scope global ens33
valid_lft forever preferred_lft forever
inet6 fe80::6b7a:2214:bef3:5850/64 scope link
valid_lft forever preferred_lft forever
3: ens34:  mtu 1500 qdisc pfifo_fast state UNKNOWN qlen 1000
link/ether 00:0c:29:a2:3a:c1 brd ff:ff:ff:ff:ff:ff
4: docker0:  mtu 1500 qdisc noqueue state DOWN
link/ether 02:42:af:00:ac:08 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
5: flannel.1:  mtu 1450 qdisc noqueue state UNKNOWN
link/ether ca:9d:fb:2c:b7:22 brd ff:ff:ff:ff:ff:ff
inet 10.244.0.0/32 brd 10.244.0.0 scope global flannel.1
valid_lft forever preferred_lft forever
inet6 fe80::c89d:fbff:fe2c:b722/64 scope link
valid_lft forever preferred_lft forever
6: cni0:  mtu 1450 qdisc noqueue state UP qlen 1000
link/ether 3e:f7:13:d6:6b:5b brd ff:ff:ff:ff:ff:ff
inet 10.244.0.1/24 brd 10.244.0.255 scope global cni0
valid_lft forever preferred_lft forever
inet6 fe80::3cf7:13ff:fed6:6b5b/64 scope link
valid_lft forever preferred_lft forever
7: vethf9bacd46@if3:  mtu 1450 qdisc noqueue master cni0 state UP
link/ether f6:9d:2c:f7:ff:4e brd ff:ff:ff:ff:ff:ff link-netnsid 0
inet6 fe80::f49d:2cff:fef7:ff4e/64 scope link
valid_lft forever preferred_lft forever
8: veth59372586@if3:  mtu 1450 qdisc noqueue master cni0 state UP
link/ether 56:da:7b:cb:75:49 brd ff:ff:ff:ff:ff:ff link-netnsid 1
inet6 fe80::54da:7bff:fecb:7549/64 scope link
valid_lft forever preferred_lft forever
[root@mcwk8s-master ~]$ 

node1
[root@mcwk8s-node1 ~]$ route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
0.0.0.0         10.0.0.253      0.0.0.0         UG    100    0        0 ens33
10.0.0.0        0.0.0.0         255.255.255.0   U     100    0        0 ens33
10.244.0.0      10.244.0.0      255.255.255.0   UG    0      0        0 flannel.1
10.244.1.0      0.0.0.0         255.255.255.0   U     0      0        0 cni0
10.244.2.0      10.244.2.0      255.255.255.0   UG    0      0        0 flannel.1
172.17.0.0      0.0.0.0         255.255.0.0     U     0      0        0 docker0
[root@mcwk8s-node1 ~]$ ip a
1: lo:  mtu 65536 qdisc noqueue state UNKNOWN qlen 1
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: ens34:  mtu 1500 qdisc pfifo_fast state UNKNOWN qlen 1000
link/ether 00:0c:29:0b:a3:15 brd ff:ff:ff:ff:ff:ff
3: ens33:  mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 00:0c:29:0b:a3:0b brd ff:ff:ff:ff:ff:ff
inet 10.0.0.5/24 brd 10.0.0.255 scope global ens33
valid_lft forever preferred_lft forever
inet6 fe80::3516:c22b:d62:c43f/64 scope link
valid_lft forever preferred_lft forever
4: docker0:  mtu 1500 qdisc noqueue state DOWN
link/ether 02:42:5e:08:56:63 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
5: flannel.1:  mtu 1450 qdisc noqueue state UNKNOWN
link/ether 4e:92:a2:b0:6b:5a brd ff:ff:ff:ff:ff:ff
inet 10.244.1.0/32 brd 10.244.1.0 scope global flannel.1
valid_lft forever preferred_lft forever
inet6 fe80::4c92:a2ff:feb0:6b5a/64 scope link
valid_lft forever preferred_lft forever
6: cni0:  mtu 1450 qdisc noqueue state UP qlen 1000
link/ether e2:d3:b2:00:28:bf brd ff:ff:ff:ff:ff:ff
inet 10.244.1.1/24 brd 10.244.1.255 scope global cni0
valid_lft forever preferred_lft forever
inet6 fe80::e0d3:b2ff:fe00:28bf/64 scope link
valid_lft forever preferred_lft forever
7: vethafc53bc5@if3:  mtu 1450 qdisc noqueue master cni0 state UP
link/ether 32:51:41:e9:e1:68 brd ff:ff:ff:ff:ff:ff link-netnsid 0
inet6 fe80::3051:41ff:fee9:e168/64 scope link
valid_lft forever preferred_lft forever
8: veth8246ed1c@if3:  mtu 1450 qdisc noqueue master cni0 state UP
link/ether 12:67:28:44:fa:cd brd ff:ff:ff:ff:ff:ff link-netnsid 1
inet6 fe80::1067:28ff:fe44:facd/64 scope link
valid_lft forever preferred_lft forever
[root@mcwk8s-node1 ~]$ 

node2
[root@mcwk8s-node2 ~]$ route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
0.0.0.0         10.0.0.253      0.0.0.0         UG    100    0        0 ens33
10.0.0.0        0.0.0.0         255.255.255.0   U     100    0        0 ens33
10.244.0.0      10.244.0.0      255.255.255.0   UG    0      0        0 flannel.1
10.244.1.0      10.244.1.0      255.255.255.0   UG    0      0        0 flannel.1
10.244.2.0      0.0.0.0         255.255.255.0   U     0      0        0 cni0
172.17.0.0      0.0.0.0         255.255.0.0     U     0      0        0 docker0
You have new mail in /var/spool/mail/root
[root@mcwk8s-node2 ~]$ ip a
1: lo:  mtu 65536 qdisc noqueue state UNKNOWN qlen 1
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: ens34:  mtu 1500 qdisc pfifo_fast state UNKNOWN qlen 1000
link/ether 00:0c:29:eb:83:cd brd ff:ff:ff:ff:ff:ff
3: ens33:  mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 00:0c:29:eb:83:c3 brd ff:ff:ff:ff:ff:ff
inet 10.0.0.6/24 brd 10.0.0.255 scope global ens33
valid_lft forever preferred_lft forever
inet6 fe80::fd02:359f:93a4:95af/64 scope link
valid_lft forever preferred_lft forever
4: docker0:  mtu 1500 qdisc noqueue state DOWN
link/ether 02:42:ff:3f:37:b0 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
5: flannel.1:  mtu 1450 qdisc noqueue state UNKNOWN
link/ether 56:16:44:85:ca:57 brd ff:ff:ff:ff:ff:ff
inet 10.244.2.0/32 brd 10.244.2.0 scope global flannel.1
valid_lft forever preferred_lft forever
inet6 fe80::5416:44ff:fe85:ca57/64 scope link
valid_lft forever preferred_lft forever
6: cni0:  mtu 1450 qdisc noqueue state UP qlen 1000
link/ether 06:1f:10:ee:32:6f brd ff:ff:ff:ff:ff:ff
inet 10.244.2.1/24 brd 10.244.2.255 scope global cni0
valid_lft forever preferred_lft forever
inet6 fe80::41f:10ff:feee:326f/64 scope link
valid_lft forever preferred_lft forever
7: vethdf3032e1@if3:  mtu 1450 qdisc noqueue master cni0 state UP
link/ether 1e:50:bf:95:46:4d brd ff:ff:ff:ff:ff:ff link-netnsid 0
inet6 fe80::1c50:bfff:fe95:464d/64 scope link
valid_lft forever preferred_lft forever
[root@mcwk8s-node2 ~]$ 

[machangwei@mcwk8s-master ~]$ kubectl get pod -o wide
NAME                         READY   STATUS              RESTARTS   AGE     IP       NODE           NOMINATED NODE   READINESS GATES
mcw-httpd-6fbf67d7d5-5qfrl   0/1     ContainerCreating   0          5m19s      mcwk8s-node1              
mcw-httpd-6fbf67d7d5-98x8d   0/1     ContainerCreating   0          5m19s      mcwk8s-node2              
mcw-httpd-6fbf67d7d5-bpbq4   0/1     ContainerCreating   0          5m19s      mcwk8s-node1              
[machangwei@mcwk8s-master ~]$ kubectl describe pod mcw-httpd-6fbf67d7d5-5qfrl
Events:  #容器创建中的状态时间段，包括拉取镜像的过程
Type    Reason     Age    From               Message
----    ------     ----   ----               -------
Normal  Scheduled  4m49s  default-scheduler  Successfully assigned default/mcw-httpd-6fbf67d7d5-5qfrl to mcwk8s-node1
Normal  Pulling    4m35s  kubelet            Pulling image "httpd"

 mcwk8s-node1一直卡在拉取不下镜像，然后手动到节点1上docker pull,拉取完镜像之后，pod马上就运行状态了
[machangwei@mcwk8s-master ~]$ kubectl get pod -o wide
NAME                         READY   STATUS    RESTARTS   AGE   IP           NODE           NOMINATED NODE   READINESS GATES
mcw-httpd-6fbf67d7d5-5qfrl   1/1     Running   0          21m   10.244.1.2   mcwk8s-node1              
mcw-httpd-6fbf67d7d5-98x8d   1/1     Running   0          21m   10.244.2.2   mcwk8s-node2              
mcw-httpd-6fbf67d7d5-bpbq4   1/1     Running   0          21m   10.244.1.3   mcwk8s-node1              
[machangwei@mcwk8s-master ~]$ 

查看网络，现在分配的pod上分配的ip，可以正常的在集群其它节点上进行访问了。也就是Pod分配了各自的ip,这些ip只能被Kuernetes Cluster 中的容器和节点访问。前面那句话已经得到验证
[machangwei@mcwk8s-master ~]$ kubectl get pod -o wide
NAME                         READY   STATUS    RESTARTS   AGE   IP           NODE           NOMINATED NODE   READINESS GATES
mcw-httpd-6fbf67d7d5-5qfrl   1/1     Running   0          21m   10.244.1.2   mcwk8s-node1              
mcw-httpd-6fbf67d7d5-98x8d   1/1     Running   0          21m   10.244.2.2   mcwk8s-node2              
mcw-httpd-6fbf67d7d5-bpbq4   1/1     Running   0          21m   10.244.1.3   mcwk8s-node1              
[machangwei@mcwk8s-master ~]$ curl 10.244.1.2
It works!

[machangwei@mcwk8s-master ~]$ curl 10.244.1.3
It works!

[machangwei@mcwk8s-master ~]$ hostname
mcwk8s-master
[machangwei@mcwk8s-master ~]$ 

endpoint是空的，肯定不能通过服务ip加端口，去curl访问服务的响应数据
[machangwei@mcwk8s-master ~]$ cat mcwHttpdService.yml
apiVersion: v1
kind: Service
metadata:
name: httpd-svc
spec:
selector:
run: httpd
ports:
- protocol: TCP
port: 8080
targetPort: 80
[machangwei@mcwk8s-master ~]$ kubectl apply -f mcwHttpdService.yml  #创建Service
service/httpd-svc created
[machangwei@mcwk8s-master ~]$ kubectl get service #查看service。有服务名，集群ip,以及端口，
NAME         TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)    AGE
httpd-svc    ClusterIP   10.102.232.38           8080/TCP   11s
kubernetes   ClusterIP   10.96.0.1               443/TCP    140m
[machangwei@mcwk8s-master ~]$ curl 10.102.232.38:8080  #通过curl集群ip冒号端口，无法访问，因为没有endpoint
curl: (7) Failed connect to 10.102.232.38:8080; Connection refused
[machangwei@mcwk8s-master ~]$ curl 10.244.1.2  #通过访问pod ip ，可以直接在节点上访问到集群中的pod的对应的80服务
It works!

[machangwei@mcwk8s-master ~]$
[machangwei@mcwk8s-master ~]$ ping 10.244.1.2  #可以在节点上ping通集群中pod的ip。
PING 10.244.1.2 (10.244.1.2) 56(84) bytes of data.
64 bytes from 10.244.1.2: icmp_seq=1 ttl=63 time=1.04 ms
[machangwei@mcwk8s-master ~]$
[machangwei@mcwk8s-master ~]$ kubectl get service
NAME         TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)    AGE
httpd-svc    ClusterIP   10.102.232.38           8080/TCP   75s
kubernetes   ClusterIP   10.96.0.1               443/TCP    141m
[machangwei@mcwk8s-master ~]$ curl 10.102.232.38:8080
curl: (7) Failed connect to 10.102.232.38:8080; Connection refused
[machangwei@mcwk8s-master ~]$ kubectl describe service httpd-svc  #查看服务，可以看到endponts为none
Name:              httpd-svc
Namespace:         default
Labels:            
Annotations:       
Selector:          run=httpd
Type:              ClusterIP
IP Family Policy:  SingleStack
IP Families:       IPv4
IP:                10.102.232.38
IPs:               10.102.232.38
Port:                8080/TCP
TargetPort:        80/TCP
Endpoints:         
Session Affinity:  None
Events:            
[machangwei@mcwk8s-master ~]$ 

[machangwei@mcwk8s-master ~]$ cat mcwHttpdService.yml   #修改前的yml文件，
apiVersion: v1
kind: Service
metadata:
name: httpd-svc
spec:
selector:
run: httpd
ports:
- protocol: TCP
port: 8080
targetPort: 80
[machangwei@mcwk8s-master ~]$ kubectl get pod --show-labels  #查看服务对应的后端pod的标签，发现是run=mcw-httpd，
NAME                         READY   STATUS    RESTARTS   AGE    LABELS
mcw-httpd-6fbf67d7d5-5qfrl   1/1     Running   0          107m   pod-template-hash=6fbf67d7d5,run=mcw-httpd
mcw-httpd-6fbf67d7d5-98x8d   1/1     Running   0          107m   pod-template-hash=6fbf67d7d5,run=mcw-httpd
mcw-httpd-6fbf67d7d5-bpbq4   1/1     Running   0          107m   pod-template-hash=6fbf67d7d5,run=mcw-httpd
[machangwei@mcwk8s-master ~]$ kubectl delete -f mcwHttpdService.yml
service "httpd-svc" deleted
[machangwei@mcwk8s-master ~]$ vim mcwHttpdService.yml
[machangwei@mcwk8s-master ~]$ cat mcwHttpdService.yml #修改选择器，纠正标签，指定service后端pod的标签是run: mcw-httpd
apiVersion: v1
kind: Service
metadata:
name: httpd-svc
spec:
selector:
run: mcw-httpd
ports:
- protocol: TCP
port: 8080
targetPort: 80
[machangwei@mcwk8s-master ~]$ kubectl apply -f mcwHttpdService.yml #重新部署服务
service/httpd-svc created
[machangwei@mcwk8s-master ~]$ kubectl get service #查看服务，集群已经换掉了
NAME         TYPE        CLUSTER-IP     EXTERNAL-IP   PORT(S)    AGE
httpd-svc    ClusterIP   10.99.19.228           8080/TCP   7s
kubernetes   ClusterIP   10.96.0.1              443/TCP    146m
[machangwei@mcwk8s-master ~]$ curl 10.99.19.228:8080  #这下可以正常curl 集群IP:端口，来访问服务了。
It works!

[machangwei@mcwk8s-master ~]$ kubectl describe service httpd-svc
Name:              httpd-svc
Namespace:         default
Labels:            
Annotations:       
Selector:          run=mcw-httpd
Type:              ClusterIP
IP Family Policy:  SingleStack
IP Families:       IPv4
IP:                10.99.19.228
IPs:               10.99.19.228
Port:                8080/TCP  #查看到现在的服务，后endpoint的值
TargetPort:        80/TCP     #  endpoint的值，是代表有可以访问带有指定标签pod ip，指定pod目标端口的服务。
Endpoints:         10.244.1.2:80,10.244.1.3:80,10.244.2.2:80
Session Affinity:  None    #也就是访问集群ip:端口，应该是负载均衡路由到这带有服务选择对应标签的pod ip和目标端口的
Events:              #集群ip是创建服务时分配的，而选择带有什么样标签的pod,以及pod对应服务的端口,即目标端口，是在yml里面已经设置好了
[machangwei@mcwk8s-master ~]$ 

[machangwei@mcwk8s-master ~]$ cat mcwHttpdService.yml
apiVersion: v1  #Service的apiVersion
kind: Service #资源类型
metadata:
name: httpd-svc
spec:
selector:  #指明挑选那些label为run: httpd的pod作为Service的后端
run: httpd
ports:
- protocol: TCP
port: 8080  #将Servicede 8080端口映射到Pod的80端口，使用TCP协议
targetPort: 80

跟service相关的防火墙规则，集群ip和pod ip相关
[machangwei@mcwk8s-master ~]$  kubectl get pod -o wide
NAME                         READY   STATUS    RESTARTS   AGE   IP           NODE           NOMINATED NODE   READINESS GATES
mcw-httpd-6fbf67d7d5-5qfrl   1/1     Running   0          20h   10.244.1.2   mcwk8s-node1              
mcw-httpd-6fbf67d7d5-98x8d   1/1     Running   0          20h   10.244.2.2   mcwk8s-node2              
mcw-httpd-6fbf67d7d5-bpbq4   1/1     Running   0          20h   10.244.1.3   mcwk8s-node1              
[machangwei@mcwk8s-master ~]$ kubectl get service
NAME         TYPE        CLUSTER-IP     EXTERNAL-IP   PORT(S)    AGE
httpd-svc    ClusterIP   10.99.19.228           8080/TCP   18h
kubernetes   ClusterIP   10.96.0.1              443/TCP    20h
[machangwei@mcwk8s-master ~]$ 

查看当前主机防火墙
[root@mcwk8s-master ~]$ iptables-save |grep httpd-svc
-A KUBE-SEP-26GESA23ILIBJ6BG -s 10.244.1.2/32 -m comment --comment "default/httpd-svc" -j KUBE-MARK-MASQ
-A KUBE-SEP-26GESA23ILIBJ6BG -p tcp -m comment --comment "default/httpd-svc" -m tcp -j DNAT --to-destination 10.244.1.2:80
-A KUBE-SEP-5MDWNIS6FGKOLKLF -s 10.244.1.3/32 -m comment --comment "default/httpd-svc" -j KUBE-MARK-MASQ
-A KUBE-SEP-5MDWNIS6FGKOLKLF -p tcp -m comment --comment "default/httpd-svc" -m tcp -j DNAT --to-destination 10.244.1.3:80
-A KUBE-SEP-MZ7D7IEY543CBPN3 -s 10.244.2.2/32 -m comment --comment "default/httpd-svc" -j KUBE-MARK-MASQ
-A KUBE-SEP-MZ7D7IEY543CBPN3 -p tcp -m comment --comment "default/httpd-svc" -m tcp -j DNAT --to-destination 10.244.2.2:80
-A KUBE-SERVICES -d 10.99.19.228/32 -p tcp -m comment --comment "default/httpd-svc cluster IP" -m tcp --dport 8080 -j KUBE-SVC-IYRDZZKXS5EOQ6Q6
-A KUBE-SVC-IYRDZZKXS5EOQ6Q6 ! -s 10.244.0.0/16 -d 10.99.19.228/32 -p tcp -m comment --comment "default/httpd-svc cluster IP" -m tcp --dport 8080 -j KUBE-MARK-MASQ
-A KUBE-SVC-IYRDZZKXS5EOQ6Q6 -m comment --comment "default/httpd-svc" -m statistic --mode random --probability 0.33333333349 -j KUBE-SEP-26GESA23ILIBJ6BG
-A KUBE-SVC-IYRDZZKXS5EOQ6Q6 -m comment --comment "default/httpd-svc" -m statistic --mode random --probability 0.50000000000 -j KUBE-SEP-5MDWNIS6FGKOLKLF
-A KUBE-SVC-IYRDZZKXS5EOQ6Q6 -m comment --comment "default/httpd-svc" -j KUBE-SEP-MZ7D7IEY543CBPN3
[root@mcwk8s-master ~]$ 

一：
-A KUBE-SERVICES -d 10.99.19.228/32 -p tcp -m comment --comment "default/httpd-svc cluster IP" -m tcp --dport 8080 -j KUBE-SVC-IYRDZZKXS5EOQ6Q6
-A KUBE-SVC-IYRDZZKXS5EOQ6Q6 ! -s 10.244.0.0/16 -d 10.99.19.228/32 -p tcp -m comment --comment "default/httpd-svc cluster IP" -m tcp --dport 8080 -j KUBE-MARK-MASQ
1、其它源地址访问httpd-svc，则允许
2、如果Cluster内的pod(源地址来自10.244.0.0/16)要访问httpd-svc，则跳转到KUBE-SVC-IYRDZZKXS5EOQ6Q6

KUBE-SVC-IYRDZZKXS5EOQ6Q6规则之一如下：
-A KUBE-SVC-IYRDZZKXS5EOQ6Q6 -m comment --comment "default/httpd-svc" -m statistic --mode random --probability 0.33333333349 -j KUBE-SEP-26GESA23ILIBJ6BG

二：
-A KUBE-SVC-IYRDZZKXS5EOQ6Q6 -m comment --comment "default/httpd-svc" -m statistic --mode random --probability 0.33333333349 -j KUBE-SEP-26GESA23ILIBJ6BG
-A KUBE-SVC-IYRDZZKXS5EOQ6Q6 -m comment --comment "default/httpd-svc" -m statistic --mode random --probability 0.50000000000 -j KUBE-SEP-5MDWNIS6FGKOLKLF
-A KUBE-SVC-IYRDZZKXS5EOQ6Q6 -m comment --comment "default/httpd-svc" -j KUBE-SEP-MZ7D7IEY543CBPN3

1、1/3概率跳转到规则KUBE-SEP-26GESA23ILIBJ6BG
2、1/3概率（剩下2/3的一半）跳转到规则KUBE-SEP-5MDWNIS6FGKOLKLF
3、1/3概率跳转到规则KUBE-SEP-MZ7D7IEY543CBPN3

三：
-A KUBE-SEP-26GESA23ILIBJ6BG -s 10.244.1.2/32 -m comment --comment "default/httpd-svc" -j KUBE-MARK-MASQ
-A KUBE-SEP-26GESA23ILIBJ6BG -p tcp -m comment --comment "default/httpd-svc" -m tcp -j DNAT --to-destination 10.244.1.2:80
-A KUBE-SEP-5MDWNIS6FGKOLKLF -s 10.244.1.3/32 -m comment --comment "default/httpd-svc" -j KUBE-MARK-MASQ
-A KUBE-SEP-5MDWNIS6FGKOLKLF -p tcp -m comment --comment "default/httpd-svc" -m tcp -j DNAT --to-destination 10.244.1.3:80
-A KUBE-SEP-MZ7D7IEY543CBPN3 -s 10.244.2.2/32 -m comment --comment "default/httpd-svc" -j KUBE-MARK-MASQ
-A KUBE-SEP-MZ7D7IEY543CBPN3 -p tcp -m comment --comment "default/httpd-svc" -m tcp -j DNAT --to-destination 10.244.2.2:80

将请求分别转发到后端的三个pod.iptables将访问Service的流量转发到后端pod，而且使用类型轮询的负载均衡策略。集群的每一个结点都配置了相同的iptables规则，这样就确保了整个集群都能通过Service的集群ip访问服务。

[machangwei@mcwk8s-master ~]$ kubectl get deployment --namespace=kube-system #查看 dns组件
NAME      READY   UP-TO-DATE   AVAILABLE   AGE
coredns   2/2     2            2           21h
[machangwei@mcwk8s-master ~]$
[machangwei@mcwk8s-master ~]$ kubectl run mcwcentos --rm -ti --image=centos /bin/bash  #创建pod并进入
If you don't see a command prompt, try pressing enter.
[root@mcwcentos /]# wget httpd-svc.default:8080  #在pod中通过.来访问Service
bash: wget: command not found
[root@mcwcentos /]# curl httpd-svc.default:8080
It works!

[root@mcwcentos /]#
[root@mcwcentos /]# curl httpd-svc:8080  #因为pod和httpd-svc同属于default namespace,因此可以省略default命名空间，直接访问服务
It works!

[root@mcwcentos /]# yum -y install bind-utils #安装工具，以方便使用nslookup命令
Failed to set locale, defaulting to C.UTF-8
Last metadata expiration check: 0:02:36 ago on Fri Jan 21 12:45:19 2022.
Dependencies resolved.
[root@mcwcentos /]# ls /etc/yum.repos.d/  查看cenos镜像中的repo文件
CentOS-Linux-AppStream.repo  CentOS-Linux-ContinuousRelease.repo  CentOS-Linux-Devel.repo   CentOS-Linux-FastTrack.repo        CentOS-Linux-Media.repo  CentOS-Linux-PowerTools.repo
CentOS-Linux-BaseOS.repo     CentOS-Linux-Debuginfo.repo      CentOS-Linux-Extras.repo  CentOS-Linux-HighAvailability.repo    CentOS-Linux-Plus.repo     CentOS-Linux-Sources.repo
[root@mcwcentos /]# nslookup httpd-svc  #用命令查看httpd-svc的DNS信息
Server:        10.96.0.10
Address:    10.96.0.10#53

Name:    httpd-svc.default.svc.cluster.local  #这个是DNS服务器，dns组件，这个是httpd的完整域名
Address: 10.99.19.228  #可以看到这个是service的cluster ip

[root@mcwcentos /]# 

[machangwei@mcwk8s-master ~]$ kubectl get service 集群ip
NAME         TYPE        CLUSTER-IP     EXTERNAL-IP   PORT(S)    AGE
httpd-svc    ClusterIP   10.99.19.228           8080/TCP   19h
kubernetes   ClusterIP   10.96.0.1              443/TCP    21h
[machangwei@mcwk8s-master ~]$ 

查看这个新创建的pod
[machangwei@mcwk8s-master ~]$ kubectl get pod -o wide|grep mcwcentos
mcwcentos                    1/1     Running   0          8m8s   10.244.2.3   mcwk8s-node2              

到pod对应节点上找到这个容器
[root@mcwk8s-node2 ~]$  docker ps
CONTAINER ID   IMAGE                                                COMMAND                  CREATED         STATUS         PORTS     NAMES
0b11a9d9ac35   centos                                               "/bin/bash"              8 minutes ago   Up 8 minutes             k8s_mcwcentos_mcwcentos_default_05aaed6d-57b0-4f6b-807d-1cd0e9c39ad9_0

然后查看容器的日志，可以看到，记录了我进入容器后做的所有操作包括yum安装的过程
[root@mcwk8s-node2 ~]$ docker logs 0b1|tail
CentOS-Linux-AppStream.repo  CentOS-Linux-ContinuousRelease.repo  CentOS-Linux-Devel.repo   CentOS-Linux-FastTrack.repo        CentOS-Linux-Media.repo  CentOS-Linux-PowerTools.repo
CentOS-Linux-BaseOS.repo     CentOS-Linux-Debuginfo.repo      CentOS-Linux-Extras.repo  CentOS-Linux-HighAvailability.repo    CentOS-Linux-Plus.repo     CentOS-Linux-Sources.repo
[root@mcwcentos /]#
[root@mcwcentos /]# nslookup httpd-svc
Server:        10.96.0.10
Address:    10.96.0.10#53

Name:    httpd-svc.default.svc.cluster.local
Address: 10.99.19.228

[root@mcwk8s-node2 ~]$
‘

主节点进入的pod中：
[root@mcwcentos /]# ping httpd-svc
PING httpd-svc.default.svc.cluster.local (10.99.19.228) 56(84) bytes of data.
^C
--- httpd-svc.default.svc.cluster.local ping statistics ---
2 packets transmitted, 0 received, 100% packet loss, time 1001ms

[root@mcwcentos /]# curl httpd-svc
curl: (7) Failed to connect to httpd-svc port 80: Connection timed out
[root@mcwcentos /]# curl httpd-svc:8080
It works!

[root@mcwcentos /]# curl httpd-svc.default.svc.cluster.local:8080 #也可以curl完整域名，如果不加端口，不行，因为服务里显示用到这个端口了
It works!

[root@mcwcentos /]# 

查看已存在的namespcace
[machangwei@mcwk8s-master ~]$ kubectl get namespace  #这几个都是部署好集群时就已经创建好的namespace
NAME              STATUS   AGE
default           Active   21h
kube-node-lease   Active   21h
kube-public       Active   21h
kube-system       Active   21h
[machangwei@mcwk8s-master ~]$ 

查看之前部署的文件
[machangwei@mcwk8s-master ~]$ cat mcwHttpd.yml
apiVersion: apps/v1
kind: Deployment
metadata:
name: mcw-httpd
spec:
replicas: 3
selector:
matchLabels:
run: mcw-httpd
template:
metadata:
labels:
run: mcw-httpd
spec:
containers:
- name: mcw-httpd
image: httpd
ports:
- containerPort: 80
[machangwei@mcwk8s-master ~]$ cat mcwHttpdService.yml
apiVersion: v1
kind: Service
metadata:
name: httpd-svc
spec:
selector:
run: mcw-httpd
ports:
- protocol: TCP
port: 8080
targetPort: 80
[machangwei@mcwk8s-master ~]$ cat mcwhttpd2quanyml  #查看上两个文件合并修改名称，标签等信息，添加指定的命名空间。多个资源用---来分割
apiVersion: apps/v1
kind: Deployment
metadata:
name: mcw-httpd2
namespace: kube-public
spec:
replicas: 3
selector:
matchLabels:
run: mcw-httpd2
template:
metadata:
labels:
run: mcw-httpd2
spec:
containers:
- name: mcw-httpd2
image: httpd
ports:
- containerPort: 80
---
apiVersion: v1
kind: Service
metadata:
name: httpd2-svc
namespace: kube-public
spec:
selector:
run: mcw-httpd2
ports:
- protocol: TCP
port: 8080
targetPort: 80
[machangwei@mcwk8s-master ~]$

查看mcwcentos的ip
[root@mcwcentos /]# ip a
1: lo:  mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1
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
3: eth0@if8:  mtu 1450 qdisc noqueue state UP group default
link/ether c6:c1:ce:94:49:24 brd ff:ff:ff:ff:ff:ff link-netnsid 0
inet 10.244.2.3/24 brd 10.244.2.255 scope global eth0
valid_lft forever preferred_lft forever
[root@mcwcentos /]# hostname -i
10.244.2.3
[root@mcwcentos /]# 

[machangwei@mcwk8s-master ~]$ kubectl apply -f mcwhttpd2quanyml  #部署httpd2服务
deployment.apps/mcw-httpd2 created
service/httpd2-svc created
[machangwei@mcwk8s-master ~]$ kubectl get service --namespace=kube-public #查看服务2，需要指定命名空间
NAME         TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)    AGE
httpd2-svc   ClusterIP   10.101.134.243           8080/TCP   39s
[machangwei@mcwk8s-master ~]$ kubectl get service  #不指定命名空间，无法看到kube-public中的服务
NAME         TYPE        CLUSTER-IP     EXTERNAL-IP   PORT(S)    AGE
httpd-svc    ClusterIP   10.99.19.228           8080/TCP   19h
kubernetes   ClusterIP   10.96.0.1              443/TCP    21h
[machangwei@mcwk8s-master ~]$
[machangwei@mcwk8s-master ~]$ kubectl run mcwcentos2 --rm -ti --image=centos /bin/bash #运行第二个，mcwcentos2
If you don't see a command prompt, try pressing enter.
[root@mcwcentos2 /]# curl httpd2-svc:8080       #pod属于default命名空间，访问其它命名空间的服务，不指定命名空间，直接访问服务名加端口，是无法访问到
curl: (6) Could not resolve host: httpd2-svc
[root@mcwcentos2 /]# curl httpd2-svc.kube-public:8080 #加上服务名称.命名空间:服务端口，就可以实现在pod中跨命名空间访问服务
It works!

[root@mcwcentos2 /]# ping -c 2 10.244.2.3  #pod中能直接ping同一命名空间内的pod
PING 10.244.2.3 (10.244.2.3) 56(84) bytes of data.
64 bytes from 10.244.2.3: icmp_seq=1 ttl=64 time=0.252 ms
64 bytes from 10.244.2.3: icmp_seq=2 ttl=64 time=0.072 ms

--- 10.244.2.3 ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1001ms
rtt min/avg/max/mdev = 0.072/0.162/0.252/0.090 ms
[root@mcwcentos2 /]#
[root@mcwcentos2 /]# exit  #当ctrl+d退出时，这个命令创建的pod就被删除掉了，get pod也看不见这个容器
Session ended, resume using 'kubectl attach mcwcentos2 -c mcwcentos2 -i -t' command when the pod is running
pod "mcwcentos2" deleted
[machangwei@mcwk8s-master ~]$ 

如下，默认只能看到default下的pod
[machangwei@mcwk8s-master ~]$ kubectl get pod
NAME                         READY   STATUS    RESTARTS   AGE
mcw-httpd-6fbf67d7d5-5qfrl   1/1     Running   0          21h
mcw-httpd-6fbf67d7d5-98x8d   1/1     Running   0          21h
mcw-httpd-6fbf67d7d5-bpbq4   1/1     Running   0          21h
[machangwei@mcwk8s-master ~]$
[machangwei@mcwk8s-master ~]$
[machangwei@mcwk8s-master ~]$ kubectl get pod --all-namespaces
NAMESPACE     NAME                                    READY   STATUS    RESTARTS       AGE
default       mcw-httpd-6fbf67d7d5-5qfrl              1/1     Running   0              21h
default       mcw-httpd-6fbf67d7d5-98x8d              1/1     Running   0              21h
default       mcw-httpd-6fbf67d7d5-bpbq4              1/1     Running   0              21h
kube-public   mcw-httpd2-6b98bfbbbf-69jb5             1/1     Running   0              21m
kube-public   mcw-httpd2-6b98bfbbbf-qv7g9             1/1     Running   0              21m
kube-public   mcw-httpd2-6b98bfbbbf-ztddf             1/1     Running   0              21m
kube-system   coredns-6d8c4cb4d-vctxx                 1/1     Running   1 (21h ago)    22h
kube-system   coredns-6d8c4cb4d-xkv9h                 1/1     Running   0              22h

这里是在三个节点上都通过curl集群ip：端口，正常访问。如果是pod中，不同命名空间的pod中访问，结果如何，以后验证，应该也是没有问题的。
[machangwei@mcwk8s-master ~]$ kubectl get service
NAME         TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)          AGE
httpd-svc    NodePort    10.107.208.46           8080:30450/TCP   14m
kubernetes   ClusterIP   10.96.0.1               443/TCP          22h
[machangwei@mcwk8s-master ~]$ curl 10.107.208.46:8080
It works!

[root@mcwk8s-node1 ~]$ curl 10.107.208.46:8080
It works!

[root@mcwk8s-node2 ~]$ curl 10.107.208.46:8080
It works!

[root@mcwk8s-node2 ~]$ 

[machangwei@mcwk8s-master ~]$ ls   #查看当前有的yml文件
mcwhttpd2quanyml  mcwHttpdService.yml  mcwHttpd.yml  mm.yml
[machangwei@mcwk8s-master ~]$ kubectl get service #查看当前服务
NAME         TYPE        CLUSTER-IP     EXTERNAL-IP   PORT(S)    AGE
httpd-svc    ClusterIP   10.99.19.228           8080/TCP   19h
kubernetes   ClusterIP   10.96.0.1              443/TCP    22h
[machangwei@mcwk8s-master ~]$ kubectl get pod #查看当前的pod
NAME                         READY   STATUS    RESTARTS   AGE
mcw-httpd-6fbf67d7d5-5qfrl   1/1     Running   0          21h
mcw-httpd-6fbf67d7d5-98x8d   1/1     Running   0          21h
mcw-httpd-6fbf67d7d5-bpbq4   1/1     Running   0          21h
[machangwei@mcwk8s-master ~]$ kubectl delete -f mcwHttpdService.yml  #把已有的服务删除掉，一会创建新的服务，还用以前的pod
service "httpd-svc" deleted
[machangwei@mcwk8s-master ~]$ kubectl get service #查看当前有的服务，之前的一个服务已经成功删除
NAME         TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)   AGE
kubernetes   ClusterIP   10.96.0.1            443/TCP   22h
[machangwei@mcwk8s-master ~]$ vim  mcwHttpdService.yml #编辑服务yml
[machangwei@mcwk8s-master ~]$ cat mcwHttpdService.yml #将服务yml增添键值对  type: NodePort。
apiVersion: v1
kind: Service
metadata:
name: httpd-svc
spec:
type: NodePort
selector:
run: mcw-httpd
ports:
- protocol: TCP
port: 8080
targetPort: 80
[machangwei@mcwk8s-master ~]$ kubectl apply -f mcwHttpdService.yml #创建服务，好像不用删除，直接重新执行，会重新创建服务，有时间验证
service/httpd-svc created
[machangwei@mcwk8s-master ~]$ kubectl get service #查看新创建的服务，可以看到端口部分，多了一个端口，30450，
NAME         TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)          AGE
httpd-svc    NodePort    10.107.208.46           8080:30450/TCP   21s
kubernetes   ClusterIP   10.96.0.1               443/TCP          22h
[machangwei@mcwk8s-master ~]$ netstat -an|grep 30450 #查看要暴露的端口，这个端口在所有节点（node）上都有，节点ip:这个端口，都能供外网访问，供集群外的访问
tcp        0      0 0.0.0.0:30450           0.0.0.0:*               LISTEN
[machangwei@mcwk8s-master ~]$ curl 10.107.208.46:8080 #集群ip 端口访问服务
It works!

[machangwei@mcwk8s-master ~]$ curl 10.107.208.46:30450  #集群ip访问这个端口是不行的
curl: (7) Failed connect to 10.107.208.46:30450; Connection timed out
[machangwei@mcwk8s-master ~]$ kubectl get pod -o wide  #查看pod的ip
NAME                         READY   STATUS    RESTARTS   AGE   IP           NODE           NOMINATED NODE   READINESS GATES
mcw-httpd-6fbf67d7d5-5qfrl   1/1     Running   0          21h   10.244.1.2   mcwk8s-node1              
mcw-httpd-6fbf67d7d5-98x8d   1/1     Running   0          21h   10.244.2.2   mcwk8s-node2              
mcw-httpd-6fbf67d7d5-bpbq4   1/1     Running   0          21h   10.244.1.3   mcwk8s-node1              
[machangwei@mcwk8s-master ~]$ curl 10.244.1.2  #直接在节点上curl pod的ip，就能访问到服务
It works!

[machangwei@mcwk8s-master ~]$ curl 10.244.1.2:30450  #直接在节点上curl ip:要暴露的端口，是不行的
curl: (7) Failed connect to 10.244.1.2:30450; Connection refused
[machangwei@mcwk8s-master ~]$ hostname -i
10.0.0.4
[machangwei@mcwk8s-master ~]$ curl 10.0.0.4:30450  #应该用curl 节点ip:要暴露的端口
It works!

[machangwei@mcwk8s-master ~]$ curl 10.0.0.5:30450 #节点ip:这个端口，还可以在外面浏览器上访问。
It works!
   #只不过三个 节点ip加这个端口，外网访问这个服务的时候，
[machangwei@mcwk8s-master ~]$ curl 10.0.0.6:30450 #是否后端实现了负载均衡，调度到三个后端pod上呢
It works!

[machangwei@mcwk8s-master ~]$ 

主节点上找到服务的三个pod
[machangwei@mcwk8s-master ~]$ kubectl get pod -o wide
NAME                         READY   STATUS    RESTARTS   AGE   IP           NODE           NOMINATED NODE   READINESS GATES
mcw-httpd-6fbf67d7d5-5qfrl   1/1     Running   0          21h   10.244.1.2   mcwk8s-node1              
mcw-httpd-6fbf67d7d5-98x8d   1/1     Running   0          21h   10.244.2.2   mcwk8s-node2              
mcw-httpd-6fbf67d7d5-bpbq4   1/1     Running   0          21h   10.244.1.3   mcwk8s-node1              

根据三个pod信息，去节点上找到这三个容器，将容器内容修改，添加上自己的pod ip
[root@mcwk8s-node1 ~]$ netstat -an|grep 30450
tcp        0      0 0.0.0.0:30450           0.0.0.0:*               LISTEN
[root@mcwk8s-node1 ~]$ docker ps |grep mcw-httpd-6fbf67d7d5-bpbq4
c978d2770826   httpd                                                "httpd-foreground"       22 hours ago        Up 22 hours                  k8s_mcw-httpd_mcw-httpd-6fbf67d7d5-bpbq4_default_1380d70d-e2b1-4276-b80f-813bcd3bae10_0
eddd4b542888   registry.aliyuncs.com/google_containers/pause:3.6    "/pause"                 22 hours ago        Up 22 hours                  k8s_POD_mcw-httpd-6fbf67d7d5-bpbq4_default_1380d70d-e2b1-4276-b80f-813bcd3bae10_0
[root@mcwk8s-node1 ~]$ docker exec -it c978 bash
root@mcw-httpd-6fbf67d7d5-bpbq4:/usr/local/apache2# ls
bin  build  cgi-bin  conf  error  htdocs  icons  include  logs    modules
root@mcw-httpd-6fbf67d7d5-bpbq4:/usr/local/apache2# cd htdocs/
root@mcw-httpd-6fbf67d7d5-bpbq4:/usr/local/apache2/htdocs# cat index.html
It works!

root@mcw-httpd-6fbf67d7d5-bpbq4:/usr/local/apache2/htdocs# echo '
It works!
  10.244.1.3'>index.html
root@mcw-httpd-6fbf67d7d5-bpbq4:/usr/local/apache2/htdocs# 

在主节点上直接访问各个pod ip，查看都修改成功
[machangwei@mcwk8s-master ~]$ curl 10.244.1.3
It works!
  10.244.1.3
[machangwei@mcwk8s-master ~]$ 

然后根据节点ip加要暴露出去的端口，进行访问。可以发现，在节点上无论访问哪个节点ip:端口，都能实现后端三个pod的负载均衡。也就是说实现了负载均衡的。访问任意一个结点ip:加要暴露的端口，都等于访问这个服务，而这个服务后端三个pod是实现负载均衡的。在浏览器上访问，也是能看出了的,
[machangwei@mcwk8s-master ~]$ kubectl get service
NAME         TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)          AGE
httpd-svc    NodePort    10.107.208.46           8080:30450/TCP   46m
kubernetes   ClusterIP   10.96.0.1               443/TCP          23h
[machangwei@mcwk8s-master ~]$ hostname -i
10.0.0.4
[machangwei@mcwk8s-master ~]$ curl 10.0.0.4:30450
It works!
  10.244.2.2
[machangwei@mcwk8s-master ~]$ curl 10.0.0.4:30450
It works!
  10.244.1.2
[machangwei@mcwk8s-master ~]$ curl 10.0.0.4:30450
It works!
  10.244.2.2
[machangwei@mcwk8s-master ~]$ curl 10.0.0.4:30450
It works!
  10.244.2.2
[machangwei@mcwk8s-master ~]$ curl 10.0.0.4:30450
It works!
  10.244.2.2
[machangwei@mcwk8s-master ~]$ curl 10.0.0.4:30450
It works!
  10.244.1.2
[machangwei@mcwk8s-master ~]$ curl 10.0.0.4:30450
It works!
  10.244.1.3
[machangwei@mcwk8s-master ~]$ curl 10.0.0.4:30450
It works!
  10.244.2.2

[machangwei@mcwk8s-master ~]$ curl 10.0.0.5:30450
It works!
  10.244.1.2
[machangwei@mcwk8s-master ~]$ curl 10.0.0.5:30450
It works!
  10.244.1.3