环境
03 master ,05 06是node
[root@mcwk8s03 mcwtest]# kubectl get nodes -o wide
NAME STATUS ROLES AGE VERSION INTERNAL-IP EXTERNAL-IP OS-IMAGE KERNEL-VERSION CONTAINER-RUNTIME
mcwk8s05 Ready <none> 581d v1.15.12 10.0.0.35 <none> CentOS Linux 7 (Core) 3.10.0-693.el7.x86_64 docker://20.10.21
mcwk8s06 Ready <none> 581d v1.15.12 10.0.0.36 <none> CentOS Linux 7 (Core) 3.10.0-693.el7.x86_64 docker://20.10.21
[root@mcwk8s03 mcwtest]#[root@mcwk8s03 mcwtest]# kubectl get svc
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kubernetes ClusterIP 10.2.0.1 <none> 443/TCP 584d
mcwtest-svc NodePort 10.2.0.155 <none> 2024:33958/TCP 26h
nginx ClusterIP None <none> 80/TCP 414d
[root@mcwk8s03 mcwtest]# kubectl get svc|grep mcwtest
mcwtest-svc NodePort 10.2.0.155 <none> 2024:33958/TCP 26h
[root@mcwk8s03 mcwtest]# kubectl get deploy|grep mcwtest
mcwtest-deploy 1/1 1 1 26h
[root@mcwk8s03 mcwtest]# kubectl get pod|grep mcwtest
mcwtest-deploy-6465665557-g9zjd 1/1 Running 1 25h
[root@mcwk8s03 mcwtest]# kubectl get pod -o wide|grep mcwtest
mcwtest-deploy-6465665557-g9zjd 1/1 Running 1 25h 172.17.89.10 mcwk8s05 <none> <none>
[root@mcwk8s03 mcwtest]# 停止服务之前，可以正常用nodeip: nodeport访问
[root@mcwk8s03 mcwtest]# kubectl get svc
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kubernetes ClusterIP 10.2.0.1 <none> 443/TCP 584d
mcwtest-svc NodePort 10.2.0.155 <none> 2024:33958/TCP 26h
nginx ClusterIP None <none> 80/TCP 414d
[root@mcwk8s03 mcwtest]# date
Thu Jun 6 00:50:34 CST 2024
[root@mcwk8s03 mcwtest]# curl -I 10.0.0.35:33958
HTTP/1.0 200 OK
Server: SimpleHTTP/0.6 Python/2.7.18
Date: Wed, 05 Jun 2024 16:50:42 GMT
Content-type: text/html; charset=ANSI_X3.4-1968
Content-Length: 816
[root@mcwk8s03 mcwtest]# curl -I 10.0.0.36:33958
HTTP/1.0 200 OK
Server: SimpleHTTP/0.6 Python/2.7.18
Date: Wed, 05 Jun 2024 16:50:46 GMT
Content-type: text/html; charset=ANSI_X3.4-1968
Content-Length: 816
[root@mcwk8s03 mcwtest]# 【】停止master上的组件
[root@mcwk8s03 /]# systemctl stop kube-apiserver.service
[root@mcwk8s03 /]# systemctl status kube-apiserver.service
● kube-apiserver.service - Kubernetes API Server
Loaded: loaded (/usr/lib/systemd/system/kube-apiserver.service; enabled; vendor preset: disabled)
Active: inactive (dead) since Thu 2024-06-06 00:54:51 CST; 14s ago
Docs: https://github.com/kubernetes/kubernetes
Process: 19837 ExecStart=/opt/kubernetes/bin/kube-apiserver $KUBE_APISERVER_OPTS (code=exited, status=0/SUCCESS)
Main PID: 19837 (code=exited, status=0/SUCCESS)
Jun 06 00:54:51 mcwk8s03 kube-apiserver[19837]: I0606 00:54:51.395965 19837 wrap.go:47] GET /apis/rbac.authorization.k8s.io/v1/clus...3:5887]
Jun 06 00:54:51 mcwk8s03 kube-apiserver[19837]: I0606 00:54:51.396002 19837 wrap.go:47] GET /apis/storage.k8s.io/v1/volumeattachmen...3:5887]
Jun 06 00:54:51 mcwk8s03 kube-apiserver[19837]: I0606 00:54:51.396033 19837 wrap.go:47] GET /apis/admissionregistration.k8s.io/v1be...3:5887]
Jun 06 00:54:51 mcwk8s03 kube-apiserver[19837]: I0606 00:54:51.396047 19837 wrap.go:47] GET /apis/rbac.authorization.k8s.io/v1/role...3:5887]
Jun 06 00:54:51 mcwk8s03 kube-apiserver[19837]: I0606 00:54:51.396068 19837 wrap.go:47] GET /api/v1/nodes?resourceVersion=4830599&t...3:5887]
Jun 06 00:54:51 mcwk8s03 kube-apiserver[19837]: I0606 00:54:51.396083 19837 wrap.go:47] GET /api/v1/secrets?resourceVersion=4710803...3:5887]
Jun 06 00:54:51 mcwk8s03 kube-apiserver[19837]: I0606 00:54:51.396108 19837 wrap.go:47] GET /api/v1/namespaces?resourceVersion=4710...3:5887]
Jun 06 00:54:51 mcwk8s03 kube-apiserver[19837]: I0606 00:54:51.405097 19837 wrap.go:47] GET /api/v1/namespaces/default/endpoints/ku...3:5887]
Jun 06 00:54:51 mcwk8s03 kube-apiserver[19837]: E0606 00:54:51.408262 19837 controller.go:179] no master IPs were listed in storage...service
Jun 06 00:54:51 mcwk8s03 systemd[1]: Stopped Kubernetes API Server.
Hint: Some lines were ellipsized, use -l to show in full.
[root@mcwk8s03 /]# 执行命令已经有问题了
[root@mcwk8s03 /]# kubectl get svc
The connection to the server localhost:8080 was refused - did you specify the right host or port?
[root@mcwk8s03 /]# kubectl get nodes
The connection to the server localhost:8080 was refused - did you specify the right host or port?
[root@mcwk8s03 /]# /var/log/message报错
Jun 6 00:58:11 mcwk8s03 kube-scheduler: E0606 00:58:11.720321 123920 reflector.go:125] k8s.io/client-go/informers/factory.go:133:
Failed to list *v1.ReplicaSet: Get http://127.0.0.1:8080/apis/apps/v1/replicasets?limit=500&resourceVersion=0: dial tcp 127.0.0.1:8080: connect: connection refusednodeip:nodeport的容器没有受到影响，还在运行
[root@mcwk8s03 mcwtest]# curl -I 10.0.0.36:33958
HTTP/1.0 200 OK
Server: SimpleHTTP/0.6 Python/2.7.18
Date: Wed, 05 Jun 2024 17:01:02 GMT
Content-type: text/html; charset=ANSI_X3.4-1968
Content-Length: 816
[root@mcwk8s03 mcwtest]# date
Thu Jun 6 01:01:12 CST 2024
[root@mcwk8s03 mcwtest]# 还能正常访问
停掉schedule和controller-manager，pod可以正常提供服务
[root@mcwk8s03 mcwtest]# systemctl stop kube-scheduler.service
[root@mcwk8s03 mcwtest]# systemctl stop kube-controller-manager.service
[root@mcwk8s03 mcwtest]# date
Thu Jun 6 01:03:23 CST 2024
[root@mcwk8s03 mcwtest]# curl -I 10.0.0.36:33958
HTTP/1.0 200 OK
Server: SimpleHTTP/0.6 Python/2.7.18
Date: Wed, 05 Jun 2024 17:03:26 GMT
Content-type: text/html; charset=ANSI_X3.4-1968
Content-Length: 816
[root@mcwk8s03 mcwtest]# master没有kubelet和kube proxy
[root@mcwk8s03 mcwtest]# ps -ef|grep proxy
root 125098 1429 0 01:05 pts/0 00:00:00 grep --color=auto proxy
[root@mcwk8s03 mcwtest]# ps -ef|grep let
root 125106 1429 0 01:05 pts/0 00:00:00 grep --color=auto let
[root@mcwk8s03 mcwtest]# 【3】停掉node上的组件
[root@mcwk8s03 mcwtest]# curl -I 10.0.0.36:33958
HTTP/1.0 200 OK
Server: SimpleHTTP/0.6 Python/2.7.18
Date: Wed, 05 Jun 2024 17:06:41 GMT
Content-type: text/html; charset=ANSI_X3.4-1968
Content-Length: 816
[root@mcwk8s03 mcwtest]# curl -I 10.0.0.35:33958
HTTP/1.0 200 OK
Server: SimpleHTTP/0.6 Python/2.7.18
Date: Wed, 05 Jun 2024 17:06:44 GMT
Content-type: text/html; charset=ANSI_X3.4-1968
Content-Length: 816
[root@mcwk8s03 mcwtest]# 既然master不影响已有pod的正常使用，那么先把apiserver的启动一下，方便看环境
我们master上只启动了apiserver组件的，启动之后就可以看到，pod等信息正常显示
[root@mcwk8s03 mcwtest]# systemctl start apiserver
Failed to start apiserver.service: Unit not found.
[root@mcwk8s03 mcwtest]# systemctl start kube-apiserver.service
[root@mcwk8s03 mcwtest]# kubectl get svc
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kubernetes ClusterIP 10.2.0.1 <none> 443/TCP 584d
mcwtest-svc NodePort 10.2.0.155 <none> 2024:33958/TCP 26h
nginx ClusterIP None <none> 80/TCP 414d
[root@mcwk8s03 mcwtest]# kubectl get nodes
NAME STATUS ROLES AGE VERSION
mcwk8s05 Ready <none> 581d v1.15.12
mcwk8s06 Ready <none> 581d v1.15.12
[root@mcwk8s03 mcwtest]# 查看组件状态，也就是这三个，不影响已有pod的nodeip:nodeport方式的访问。
[root@mcwk8s03 mcwtest]# kubectl get cs
NAME STATUS MESSAGE ERROR
scheduler Unhealthy Get http://127.0.0.1:10251/healthz: dial tcp 127.0.0.1:10251: connect: connection refused
controller-manager Unhealthy Get http://127.0.0.1:10252/healthz: dial tcp 127.0.0.1:10252: connect: connection refused
etcd-1 Healthy {"health":"true"}
etcd-2 Healthy {"health":"true"}
etcd-0 Healthy {"health":"true"}
[root@mcwk8s03 mcwtest]#我们master看下，找个clusterIP
[root@mcwk8s03 mcwtest]# kubectl get svc
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kubernetes ClusterIP 10.2.0.1 <none> 443/TCP 584d
mcwtest-svc NodePort 10.2.0.155 <none> 2024:33958/TCP 26h
nginx ClusterIP None <none> 80/TCP 414d
[root@mcwk8s03 mcwtest]# 然后去node上访问一下，也是可以正常访问的。为啥不在master请求clusterIP：port，这是因为没有ipvsadm规则，master没有部署kubeproxy这些node上的服务把
[root@mcwk8s05 ~]# curl -I 10.2.0.155:2024
HTTP/1.0 200 OK
Server: SimpleHTTP/0.6 Python/2.7.18
Date: Wed, 05 Jun 2024 17:12:34 GMT
Content-type: text/html; charset=ANSI_X3.4-1968
Content-Length: 816
[root@mcwk8s05 ~]# 停掉05和06上的kubelet服务
[root@mcwk8s05 ~]# systemctl stop kubelet.service
[root@mcwk8s05 ~]#
[root@mcwk8s06 ~]# systemctl stop kubelet.service
[root@mcwk8s06 ~]# 容器的nodeip:nodeport访问还是正常的，clusterIP：port访问也正常
[root@mcwk8s05 ~]# curl -I 10.0.0.35:33958
HTTP/1.0 200 OK
Server: SimpleHTTP/0.6 Python/2.7.18
Date: Wed, 05 Jun 2024 17:19:13 GMT
Content-type: text/html; charset=ANSI_X3.4-1968
Content-Length: 816
[root@mcwk8s05 ~]# curl -I 10.0.0.36:33958
HTTP/1.0 200 OK
Server: SimpleHTTP/0.6 Python/2.7.18
Date: Wed, 05 Jun 2024 17:19:17 GMT
Content-type: text/html; charset=ANSI_X3.4-1968
Content-Length: 816
[root@mcwk8s05 ~]# curl -I 10.2.0.155:2024
HTTP/1.0 200 OK
Server: SimpleHTTP/0.6 Python/2.7.18
Date: Wed, 05 Jun 2024 17:19:21 GMT
Content-type: text/html; charset=ANSI_X3.4-1968
Content-Length: 816
[root@mcwk8s05 ~]# 下面开始停止kubeproxy服务,先停止06节点的
[root@mcwk8s06 ~]# systemctl stop kube-proxy.service
[root@mcwk8s06 ~]# 06节点的nodeip:nodeport依然可以访问这个服务
[root@mcwk8s05 ~]# curl -I 10.0.0.36:33958
HTTP/1.0 200 OK
Server: SimpleHTTP/0.6 Python/2.7.18
Date: Wed, 05 Jun 2024 17:23:41 GMT
Content-type: text/html; charset=ANSI_X3.4-1968
Content-Length: 816
[root@mcwk8s05 ~]# curl -I 10.2.0.155:2024
HTTP/1.0 200 OK
Server: SimpleHTTP/0.6 Python/2.7.18
Date: Wed, 05 Jun 2024 17:23:44 GMT
Content-type: text/html; charset=ANSI_X3.4-1968
Content-Length: 816
[root@mcwk8s05 ~]# 可以看到，06上路由和ipvs规则都还在
[root@mcwk8s06 ~]# ipvsadm -Ln|grep -C 2 10.0.0.36
-> 172.17.9.2:9100 Masq 1 0 0
-> 172.17.89.2:9100 Masq 1 0 0
TCP 10.0.0.36:31672 rr
-> 172.17.9.2:9100 Masq 1 0 0
-> 172.17.89.2:9100 Masq 1 0 0
TCP 10.0.0.36:33958 rr
-> 172.17.89.10:20000 Masq 1 0 1
TCP 10.0.0.36:46735 rr
-> 172.17.89.13:3000 Masq 1 0 0
TCP 10.2.0.1:443 rr
--
TCP 172.17.9.1:46735 rr
-> 172.17.89.13:3000 Masq 1 0 0
TCP 10.0.0.36:30001 rr
-> 172.17.89.5:8443 Masq 1 0 0
TCP 10.0.0.36:30003 rr
-> 172.17.89.4:9090 Masq 1 0 0
TCP 10.2.0.155:2024 rr
[root@mcwk8s06 ~]#
[root@mcwk8s06 ~]# route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
0.0.0.0 10.0.0.254 0.0.0.0 UG 100 0 0 eth0
10.0.0.0 0.0.0.0 255.255.255.0 U 100 0 0 eth0
172.17.9.0 0.0.0.0 255.255.255.0 U 0 0 0 docker0
172.17.83.0 172.17.83.0 255.255.255.0 UG 0 0 0 flannel.1
172.17.89.0 172.17.89.0 255.255.255.0 UG 0 0 0 flannel.1
[root@mcwk8s06 ~]#pod在05机器上，把05的kube-proxy关掉，已经有的pod，也是不影响使用，目前两个node的都停掉了
[root@mcwk8s05 /]# curl -I 10.2.0.155:2024
HTTP/1.0 200 OK
Server: SimpleHTTP/0.6 Python/2.7.18
Date: Wed, 05 Jun 2024 17:26:06 GMT
Content-type: text/html; charset=ANSI_X3.4-1968
Content-Length: 816
[root@mcwk8s05 /]# curl -I 10.0.0.36:33958
HTTP/1.0 200 OK
Server: SimpleHTTP/0.6 Python/2.7.18
Date: Wed, 05 Jun 2024 17:26:34 GMT
Content-type: text/html; charset=ANSI_X3.4-1968
Content-Length: 816
[root@mcwk8s05 /]# curl -I 10.0.0.35:33958
HTTP/1.0 200 OK
Server: SimpleHTTP/0.6 Python/2.7.18
Date: Wed, 05 Jun 2024 17:26:37 GMT
Content-type: text/html; charset=ANSI_X3.4-1968
Content-Length: 816
[root@mcwk8s05 /]# [root@mcwk8s05 /]# curl -I 10.2.0.155:2024
HTTP/1.0 200 OK
Server: SimpleHTTP/0.6 Python/2.7.18
Date: Wed, 05 Jun 2024 17:26:06 GMT
Content-type: text/html; charset=ANSI_X3.4-1968
Content-Length: 816
[root@mcwk8s05 /]# curl -I 10.0.0.36:33958
HTTP/1.0 200 OK
Server: SimpleHTTP/0.6 Python/2.7.18
Date: Wed, 05 Jun 2024 17:26:34 GMT
Content-type: text/html; charset=ANSI_X3.4-1968
Content-Length: 816
[root@mcwk8s05 /]# curl -I 10.0.0.35:33958
HTTP/1.0 200 OK
Server: SimpleHTTP/0.6 Python/2.7.18
Date: Wed, 05 Jun 2024 17:26:37 GMT
Content-type: text/html; charset=ANSI_X3.4-1968
Content-Length: 816
[root@mcwk8s05 /]# 【4】停掉flannel服务。下面有个重要的分析容器通信的过程案例
停止前查看服务情况，有去两个宿主机容器网段的路由。并且nodeip:nodeport是通的。nodeip:nodeport。master上没有ipvsadm规则，因此clusterIP：port就没法找到转到对应的容器IP：容器port，但是nodeip:nodeport，不需要ipvs规则找转发的后端，直接通过nodeip通信，访问nodeport，然后到了指定的nodeip:nodeport之后，再根据ipvsadm转发规则，转发给对应的容器IP：容器Port。如果这个容器是在刚刚请求的nodeip主机上，那么直接通过docker0通信找到容器IP：容器port；如果不在这个机器，那么再通过容器跨宿主机通信的方式，再进行找到对应的宿主机，然后找到宿主机上对应的容器IP。
[root@mcwk8s03 mcwtest]# systemctl status flanneld.service
● flanneld.service - Flanneld overlay address etcd agent
Loaded: loaded (/usr/lib/systemd/system/flanneld.service; enabled; vendor preset: disabled)
Active: active (running) since Tue 2024-06-04 23:28:50 CST; 1 day 2h ago
Main PID: 11892 (flanneld)
Memory: 13.9M
CGroup: /system.slice/flanneld.service
└─11892 /opt/kubernetes/bin/flanneld --ip-masq --etcd-endpoints=https://10.0.0.33:2379,https://10.0.0.35:2379,https://10.0.0.36:2...
Warning: Journal has been rotated since unit was started. Log output is incomplete or unavailable.
[root@mcwk8s03 mcwtest]#
[root@mcwk8s03 mcwtest]#
[root@mcwk8s03 mcwtest]# route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
0.0.0.0 10.0.0.254 0.0.0.0 UG 100 0 0 eth0
10.0.0.0 0.0.0.0 255.255.255.0 U 100 0 0 eth0
172.17.9.0 172.17.9.0 255.255.255.0 UG 0 0 0 flannel.1
172.17.83.0 0.0.0.0 255.255.255.0 U 0 0 0 docker0
172.17.89.0 172.17.89.0 255.255.255.0 UG 0 0 0 flannel.1
[root@mcwk8s03 mcwtest]# ifconfig flannel.1
flannel.1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1450
inet 172.17.83.0 netmask 255.255.255.255 broadcast 0.0.0.0
inet6 fe80::b083:33ff:fe7b:fd37 prefixlen 64 scopeid 0x20<link>
ether b2:83:33:7b:fd:37 txqueuelen 0 (Ethernet)
RX packets 11 bytes 924 (924.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 11 bytes 924 (924.0 B)
TX errors 0 dropped 8 overruns 0 carrier 0 collisions 0
[root@mcwk8s03 mcwtest]# ifconfig docker
docker0: flags=4099<UP,BROADCAST,MULTICAST> mtu 1500
inet 172.17.83.1 netmask 255.255.255.0 broadcast 172.17.83.255
ether 02:42:e9:a4:51:4f txqueuelen 0 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
[root@mcwk8s03 mcwtest]# curl 10.2.0.155:2024
^C
[root@mcwk8s03 mcwtest]# curl -I 10.0.0.36:33958
HTTP/1.0 200 OK
Server: SimpleHTTP/0.6 Python/2.7.18
Date: Wed, 05 Jun 2024 17:30:23 GMT
Content-type: text/html; charset=ANSI_X3.4-1968
Content-Length: 816
[root@mcwk8s03 mcwtest]# 我们停止03master上的flannel，发现还是正常用nodeip:nodeport访问已有的容器服务的，路由还在，网卡网段还没变化。
[root@mcwk8s03 mcwtest]# route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
0.0.0.0 10.0.0.254 0.0.0.0 UG 100 0 0 eth0
10.0.0.0 0.0.0.0 255.255.255.0 U 100 0 0 eth0
172.17.9.0 172.17.9.0 255.255.255.0 UG 0 0 0 flannel.1
172.17.83.0 0.0.0.0 255.255.255.0 U 0 0 0 docker0
172.17.89.0 172.17.89.0 255.255.255.0 UG 0 0 0 flannel.1
[root@mcwk8s03 mcwtest]# ifconfig flannel.1
flannel.1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1450
inet 172.17.83.0 netmask 255.255.255.255 broadcast 0.0.0.0
inet6 fe80::b083:33ff:fe7b:fd37 prefixlen 64 scopeid 0x20<link>
ether b2:83:33:7b:fd:37 txqueuelen 0 (Ethernet)
RX packets 11 bytes 924 (924.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 11 bytes 924 (924.0 B)
TX errors 0 dropped 8 overruns 0 carrier 0 collisions 0
[root@mcwk8s03 mcwtest]# ifconfig docker
docker0: flags=4099<UP,BROADCAST,MULTICAST> mtu 1500
inet 172.17.83.1 netmask 255.255.255.0 broadcast 172.17.83.255
ether 02:42:e9:a4:51:4f txqueuelen 0 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
[root@mcwk8s03 mcwtest]# 下面我们查看下05 node的信息，准备关闭这个节点的flannel服务，正常访问pod服务
[root@mcwk8s05 ~]# systemctl status flanneld.service
● flanneld.service - Flanneld overlay address etcd agent
Loaded: loaded (/usr/lib/systemd/system/flanneld.service; disabled; vendor preset: disabled)
Active: active (running) since Wed 2024-06-05 00:50:25 CST; 24h ago
Process: 4201 ExecStartPost=/opt/kubernetes/bin/mk-docker-opts.sh -k DOCKER_NETWORK_OPTIONS -d /run/flannel/subnet.env (code=exited, status=0/SUCCESS)
Main PID: 4184 (flanneld)
Memory: 16.2M
CGroup: /system.slice/flanneld.service
└─4184 /opt/kubernetes/bin/flanneld --ip-masq --etcd-endpoints=https://10.0.0.33:2379,https://10.0.0.35:2379,https://10.0.0.36:2379 -etcd-cafile=/opt/etcd/ssl/ca.pem -etcd-cert...
Jun 05 23:50:25 mcwk8s05 flanneld[4184]: I0605 23:50:25.459783 4184 main.go:388] Lease renewed, new expiration: 2024-06-06 15:50:25.409920414 +0000 UTC
Jun 05 23:50:25 mcwk8s05 flanneld[4184]: I0605 23:50:25.459933 4184 main.go:396] Waiting for 22h59m59.949994764s to renew lease
Warning: Journal has been rotated since unit was started. Log output is incomplete or unavailable.
[root@mcwk8s05 ~]# route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
0.0.0.0 10.0.0.254 0.0.0.0 UG 100 0 0 eth0
10.0.0.0 0.0.0.0 255.255.255.0 U 100 0 0 eth0
172.17.9.0 172.17.9.0 255.255.255.0 UG 0 0 0 flannel.1
172.17.83.0 172.17.83.0 255.255.255.0 UG 0 0 0 flannel.1
172.17.89.0 0.0.0.0 255.255.255.0 U 0 0 0 docker0
[root@mcwk8s05 ~]# curl -I 10.2.0.155:2024
HTTP/1.0 200 OK
Server: SimpleHTTP/0.6 Python/2.7.18
Date: Wed, 05 Jun 2024 17:46:55 GMT
Content-type: text/html; charset=ANSI_X3.4-1968
Content-Length: 816
[root@mcwk8s05 ~]# curl -I 10.0.0.36:33958
HTTP/1.0 200 OK
Server: SimpleHTTP/0.6 Python/2.7.18
Date: Wed, 05 Jun 2024 17:47:00 GMT
Content-type: text/html; charset=ANSI_X3.4-1968
Content-Length: 816
[root@mcwk8s05 ~]# curl -I 10.0.0.35:33958
HTTP/1.0 200 OK
Server: SimpleHTTP/0.6 Python/2.7.18
Date: Wed, 05 Jun 2024 17:47:04 GMT
Content-type: text/html; charset=ANSI_X3.4-1968
Content-Length: 816
[root@mcwk8s05 ~]# ifconfig flannel.1
flannel.1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1450
inet 172.17.89.0 netmask 255.255.255.255 broadcast 0.0.0.0
inet6 fe80::3470:76ff:feea:39b8 prefixlen 64 scopeid 0x20<link>
ether 36:70:76:ea:39:b8 txqueuelen 0 (Ethernet)
RX packets 78 bytes 5468 (5.3 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 86 bytes 7144 (6.9 KiB)
TX errors 0 dropped 8 overruns 0 carrier 0 collisions 0
[root@mcwk8s05 ~]# ifconfig docker
docker0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1450
inet 172.17.89.1 netmask 255.255.255.0 broadcast 172.17.89.255
inet6 fe80::42:18ff:fee1:e8fc prefixlen 64 scopeid 0x20<link>
ether 02:42:18:e1:e8:fc txqueuelen 0 (Ethernet)
RX packets 1212277 bytes 505391601 (481.9 MiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 1374361 bytes 1966293845 (1.8 GiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
[root@mcwk8s05 ~]# 停掉两个node上的flannel服务
[root@mcwk8s05 ~]# systemctl stop flanneld.service
[root@mcwk8s05 ~]#
[root@mcwk8s06 ~]# systemctl stop flanneld.service
[root@mcwk8s06 ~]# 查看停掉所有flannel之后，05 node的信息。可以看的，依然可以访问容器服务，通过nodeip:nodeport或者是clusterip:port 。至此，k8s组件和网络插件的停止，目前来看对原有的pod是没有受到影响的。也就是，pod创建好之后，正常提供服务不会依赖k8s组件，网络组件等，也就是只有pod创建的时候，会依赖这些组件创建容器，创建好容器之后，就能正常使用，不依赖组件。
[root@mcwk8s05 ~]# curl -I 10.0.0.35:33958
HTTP/1.0 200 OK
Server: SimpleHTTP/0.6 Python/2.7.18
Date: Wed, 05 Jun 2024 17:49:28 GMT
Content-type: text/html; charset=ANSI_X3.4-1968
Content-Length: 816
[root@mcwk8s05 ~]# curl -I 10.0.0.36:33958
HTTP/1.0 200 OK
Server: SimpleHTTP/0.6 Python/2.7.18
Date: Wed, 05 Jun 2024 17:49:33 GMT
Content-type: text/html; charset=ANSI_X3.4-1968
Content-Length: 816
[root@mcwk8s05 ~]# curl -I 10.2.0.155:2024
HTTP/1.0 200 OK
Server: SimpleHTTP/0.6 Python/2.7.18
Date: Wed, 05 Jun 2024 17:49:50 GMT
Content-type: text/html; charset=ANSI_X3.4-1968
Content-Length: 816
[root@mcwk8s05 ~]# ifconfig flannel.1
flannel.1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1450
inet 172.17.89.0 netmask 255.255.255.255 broadcast 0.0.0.0
inet6 fe80::3470:76ff:feea:39b8 prefixlen 64 scopeid 0x20<link>
ether 36:70:76:ea:39:b8 txqueuelen 0 (Ethernet)
RX packets 83 bytes 5816 (5.6 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 91 bytes 7576 (7.3 KiB)
TX errors 0 dropped 8 overruns 0 carrier 0 collisions 0
[root@mcwk8s05 ~]# ifconfig docker
docker0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1450
inet 172.17.89.1 netmask 255.255.255.0 broadcast 172.17.89.255
inet6 fe80::42:18ff:fee1:e8fc prefixlen 64 scopeid 0x20<link>
ether 02:42:18:e1:e8:fc txqueuelen 0 (Ethernet)
RX packets 1213264 bytes 505536182 (482.1 MiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 1375186 bytes 1967017624 (1.8 GiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
[root@mcwk8s05 ~]# 此时在master上查看etcd中网络信息，现在将flannel网络服务启动，会不会改变该宿主机的容器网段，从而对现有的容器产生影响，导致网络问题呢。
[root@mcwk8s03 mcwtest]# etcdctl ls /
/coreos.com
[root@mcwk8s03 mcwtest]# etcdctl ls /coreos.com
/coreos.com/network
[root@mcwk8s03 mcwtest]# etcdctl ls /coreos.com/network
/coreos.com/network/config
/coreos.com/network/subnets
[root@mcwk8s03 mcwtest]# etcdctl ls /coreos.com/network/subnets/
/coreos.com/network/subnets/172.17.83.0-24
/coreos.com/network/subnets/172.17.9.0-24
/coreos.com/network/subnets/172.17.89.0-24
[root@mcwk8s03 mcwtest]# etcdctl ls /coreos.com/network/config
/coreos.com/network/config
[root@mcwk8s03 mcwtest]# etcdctl get /coreos.com/network/config
{ "Network": "172.17.0.0/16", "Backend": {"Type": "vxlan"}}
[root@mcwk8s03 mcwtest]# 网络服务启动之后，并没有改变宿主机容器网段
[root@mcwk8s05 ~]# ifconfig flannel.1
flannel.1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1450
inet 172.17.89.0 netmask 255.255.255.255 broadcast 0.0.0.0
inet6 fe80::3470:76ff:feea:39b8 prefixlen 64 scopeid 0x20<link>
ether 36:70:76:ea:39:b8 txqueuelen 0 (Ethernet)
RX packets 83 bytes 5816 (5.6 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 91 bytes 7576 (7.3 KiB)
TX errors 0 dropped 8 overruns 0 carrier 0 collisions 0
[root@mcwk8s05 ~]# ifconfig docker
docker0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1450
inet 172.17.89.1 netmask 255.255.255.0 broadcast 172.17.89.255
inet6 fe80::42:18ff:fee1:e8fc prefixlen 64 scopeid 0x20<link>
ether 02:42:18:e1:e8:fc txqueuelen 0 (Ethernet)
RX packets 1213264 bytes 505536182 (482.1 MiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 1375186 bytes 1967017624 (1.8 GiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
[root@mcwk8s05 ~]#
[root@mcwk8s05 ~]# systemctl status flanneld.service
● flanneld.service - Flanneld overlay address etcd agent
Loaded: loaded (/usr/lib/systemd/system/flanneld.service; disabled; vendor preset: disabled)
Active: inactive (dead)
Jun 05 23:50:25 mcwk8s05 flanneld[4184]: I0605 23:50:25.459783 4184 main.go:388] Lease renewed, new expiration: 2024-06-06 15:50:25.409920414 +0000 UTC
Jun 05 23:50:25 mcwk8s05 flanneld[4184]: I0605 23:50:25.459933 4184 main.go:396] Waiting for 22h59m59.949994764s to renew lease
Jun 06 01:48:25 mcwk8s05 systemd[1]: Stopping Flanneld overlay address etcd agent...
Jun 06 01:48:25 mcwk8s05 flanneld[4184]: I0606 01:48:25.715882 4184 main.go:404] Stopped monitoring lease
Jun 06 01:48:25 mcwk8s05 flanneld[4184]: I0606 01:48:25.716035 4184 main.go:322] Waiting for all goroutines to exit
Jun 06 01:48:25 mcwk8s05 flanneld[4184]: I0606 01:48:25.741648 4184 main.go:337] shutdownHandler sent cancel signal...
Jun 06 01:48:25 mcwk8s05 flanneld[4184]: I0606 01:48:25.759081 4184 main.go:325] Exiting cleanly...
Jun 06 01:48:25 mcwk8s05 systemd[1]: Stopped Flanneld overlay address etcd agent.
[root@mcwk8s05 ~]# systemctl start flanneld.service
[root@mcwk8s05 ~]# ifconfig flannel.1
flannel.1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1450
inet 172.17.89.0 netmask 255.255.255.255 broadcast 0.0.0.0
inet6 fe80::3470:76ff:feea:39b8 prefixlen 64 scopeid 0x20<link>
ether 36:70:76:ea:39:b8 txqueuelen 0 (Ethernet)
RX packets 83 bytes 5816 (5.6 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 91 bytes 7576 (7.3 KiB)
TX errors 0 dropped 8 overruns 0 carrier 0 collisions 0
[root@mcwk8s05 ~]# ifconfig docker
docker0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1450
inet 172.17.89.1 netmask 255.255.255.0 broadcast 172.17.89.255
inet6 fe80::42:18ff:fee1:e8fc prefixlen 64 scopeid 0x20<link>
ether 02:42:18:e1:e8:fc txqueuelen 0 (Ethernet)
RX packets 1216321 bytes 505986272 (482.5 MiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 1377747 bytes 1969464945 (1.8 GiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
[root@mcwk8s05 ~]# route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
0.0.0.0 10.0.0.254 0.0.0.0 UG 100 0 0 eth0
10.0.0.0 0.0.0.0 255.255.255.0 U 100 0 0 eth0
172.17.9.0 172.17.9.0 255.255.255.0 UG 0 0 0 flannel.1
172.17.83.0 172.17.83.0 255.255.255.0 UG 0 0 0 flannel.1
172.17.89.0 0.0.0.0 255.255.255.0 U 0 0 0 docker0
[root@mcwk8s05 ~]# 并且在其它节点，依然可以正常访问到容器服务
[root@mcwk8s03 mcwtest]# curl -I 10.0.0.35:33958
HTTP/1.0 200 OK
Server: SimpleHTTP/0.6 Python/2.7.18
Date: Wed, 05 Jun 2024 18:01:00 GMT
Content-type: text/html; charset=ANSI_X3.4-1968
Content-Length: 816
[root@mcwk8s03 mcwtest]#[root@mcwk8s06 ~]# systemctl stop flanneld.service
[root@mcwk8s06 ~]# curl -I 10.2.0.155:2024
HTTP/1.0 200 OK
Server: SimpleHTTP/0.6 Python/2.7.18
Date: Wed, 05 Jun 2024 18:02:02 GMT
Content-type: text/html; charset=ANSI_X3.4-1968
Content-Length: 816
[root@mcwk8s06 ~]# 我们再试一下，重启flannel服务，发现容器网段还是没有发生变化，之前遇到那些会变化的原因是什么呢？
[root@mcwk8s03 mcwtest]# etcdctl ls /coreos.com/network/subnets/
/coreos.com/network/subnets/172.17.89.0-24
/coreos.com/network/subnets/172.17.83.0-24
/coreos.com/network/subnets/172.17.9.0-24
[root@mcwk8s03 mcwtest]# ifconfig flannel.1
flannel.1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1450
inet 172.17.83.0 netmask 255.255.255.255 broadcast 0.0.0.0
inet6 fe80::b083:33ff:fe7b:fd37 prefixlen 64 scopeid 0x20<link>
ether b2:83:33:7b:fd:37 txqueuelen 0 (Ethernet)
RX packets 11 bytes 924 (924.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 11 bytes 924 (924.0 B)
TX errors 0 dropped 8 overruns 0 carrier 0 collisions 0
[root@mcwk8s03 mcwtest]# ifconfig docker
docker0: flags=4099<UP,BROADCAST,MULTICAST> mtu 1500
inet 172.17.83.1 netmask 255.255.255.0 broadcast 172.17.83.255
ether 02:42:e9:a4:51:4f txqueuelen 0 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
[root@mcwk8s03 mcwtest]# systemctl restart flanneld.service
[root@mcwk8s03 mcwtest]# etcdctl ls /coreos.com/network/subnets/
/coreos.com/network/subnets/172.17.9.0-24
/coreos.com/network/subnets/172.17.89.0-24
/coreos.com/network/subnets/172.17.83.0-24
[root@mcwk8s03 mcwtest]# ifconfig flannel.1
flannel.1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1450
inet 172.17.83.0 netmask 255.255.255.255 broadcast 0.0.0.0
inet6 fe80::b083:33ff:fe7b:fd37 prefixlen 64 scopeid 0x20<link>
ether b2:83:33:7b:fd:37 txqueuelen 0 (Ethernet)
RX packets 11 bytes 924 (924.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 11 bytes 924 (924.0 B)
TX errors 0 dropped 8 overruns 0 carrier 0 collisions 0
[root@mcwk8s03 mcwtest]# ifconfig docker
docker0: flags=4099<UP,BROADCAST,MULTICAST> mtu 1500
inet 172.17.83.1 netmask 255.255.255.0 broadcast 172.17.83.255
ether 02:42:e9:a4:51:4f txqueuelen 0 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
[root@mcwk8s03 mcwtest]# 停止etcd，对访问容器的影响
有时间再研究下停止etcd，是否会对容器正常访问造成影响呢，应该是会的吧，毕竟容器跨宿主机通信的时候，etcd保持了容器网段和宿主机ip之间的路由关系，它应该就是个路由表，有这个才能知道要访问的容器在哪个宿主机上，然后将数据包发过去，到那里再解封装然后再~~吧
综上可知：
容器创建销毁等等，需要用到k8s组件，网络插件等等。但是已经创建的容器，网络已经在宿主机上存在了，把K8S组件和网络插件停止，不影响同宿主机容器间通信，以及不影响这些容器跨主机通信。也就是已有的容器服务，clusterip：port和nodeip:nodeport等方式去访问容器应用，还是正常提供服务可以访问到的。并且我这里停止flannel之后，然后再启动，这个宿主机的容器网段还是原来的，容器网关也是原来的没有变动，etcd保存的网段也是没有变动。所以重新启动网络插件，没有使得已有的容器网段发生改变，因此有个疑问，之前为什么重启flannel服务，会让宿主机的容器网段发生改变呢，从而也要重启容器，使得所在宿主机的容器网段对应上呢