创建一个mynet的overlay网络，创建一个service
vagrant@swarm-manager:~$ docker network ls
NETWORK ID NAME DRIVER SCOPE
afc8f54c1d07 bridge bridge local
128fd1cb0fae docker_gwbridge bridge local
0ea68b0d28b9 host host local
14fy2l7a4mci ingress overlay swarm
lpirdge00y3j mynet overlay swarm
a8edf1804fb6 none null local
vagrant@swarm-manager:~$ docker service create --name web --network mynet --replicas 2 containous/whoami
jozc1x1c1zpyjl9b5j5abzm0g
overall progress: 2 out of 2 tasks
1/2: running [==================================================>]
2/2: running [==================================================>]
verify: Service converged
vagrant@swarm-manager:~$ docker service ls
ID NAME MODE REPLICAS IMAGE PORTS
jozc1x1c1zpy web replicated 2/2 containous/whoami:latest
vagrant@swarm-manager:~$ docker service ps web
ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR PORTS
pwi87g86kbxd web.1 containous/whoami:latest swarm-worker1 Running Running 47 seconds ago
xbri2akxy2e8 web.2 containous/whoami:latest swarm-worker2 Running Running 44 seconds ago
vagrant@swarm-manager:~$
创建一个client
vagrant@swarm-manager:~$ docker service create --name client --network mynet xiaopeng163/net-box:latest ping 8.8.8.8
skbcdfvgidwafbm4nciq82env
overall progress: 1 out of 1 tasks
1/1: running [==================================================>]
verify: Service converged
vagrant@swarm-manager:~$ docker service ls
ID NAME MODE REPLICAS IMAGE PORTS
skbcdfvgidwa client replicated 1/1 xiaopeng163/net-box:latest
jozc1x1c1zpy web replicated 2/2 containous/whoami:latest
vagrant@swarm-manager:~$ docker service ps client
ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR PORTS
sg9b3dqrgru4 client.1 xiaopeng163/net-box:latest swarm-manager Running Running 28 seconds ago
vagrant@swarm-manager:~$
尝试进入client这个容器，去ping web这个service name， 获取到的IP 10.0.1.30，称之为**VIP（虚拟IP）**
vagrant@swarm-manager:~$ docker container ls
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
36dce35d56e8 xiaopeng163/net-box:latest "ping 8.8.8.8" 19 minutes ago Up 19 minutes client.1.sg9b3dqrgru4f14k2tpxzg2ei
vagrant@swarm-manager:~$ docker container exec -it 36dc sh
/omd # curl web
Hostname: 6039865a1e5d
IP: 127.0.0.1
IP: 10.0.1.32
IP: 172.18.0.3
RemoteAddr: 10.0.1.37:40972
GET / HTTP/1.1
Host: web
User-Agent: curl/7.69.1
Accept: */*
/omd # curl web
Hostname: c3b3e99b9bb1
IP: 127.0.0.1
IP: 10.0.1.31
IP: 172.18.0.3
RemoteAddr: 10.0.1.37:40974
GET / HTTP/1.1
Host: web
User-Agent: curl/7.69.1
Accept: */*
/omd # curl web
Hostname: 6039865a1e5d
IP: 127.0.0.1
IP: 10.0.1.32
IP: 172.18.0.3
RemoteAddr: 10.0.1.37:40976
GET / HTTP/1.1
Host: web
User-Agent: curl/7.69.1
Accept: */*
/omd #
/omd # ping web -c 2
PING web (10.0.1.30): 56 data bytes
64 bytes from 10.0.1.30: seq=0 ttl=64 time=0.044 ms
64 bytes from 10.0.1.30: seq=1 ttl=64 time=0.071 ms
--- web ping statistics ---
2 packets transmitted, 2 packets received, 0% packet loss
round-trip min/avg/max = 0.044/0.057/0.071 ms
/omd #
这个虚拟IP在一个特殊的网络命令空间里，这个空间连接在我们的mynet这个overlay的网络上
通过 docker network inspect mynet 可以看到这个命名空间，叫lb-mynet
"Containers": {
"36dce35d56e87d43d08c5b9a94678fe789659cb3b1a5c9ddccd7de4b26e8d588": {
"Name": "client.1.sg9b3dqrgru4f14k2tpxzg2ei",
"EndpointID": "e8972d0091afaaa091886799aca164b742ca93408377d9ee599bdf91188416c1",
"MacAddress": "02:42:0a:00:01:24",
"IPv4Address": "10.0.1.36/24",
"IPv6Address": ""
},
"lb-mynet": {
"Name": "mynet-endpoint",
"EndpointID": "e299d083b25a1942f6e0f7989436c3c3e8d79c7395a80dd50b7709825022bfac",
"MacAddress": "02:42:0a:00:01:25",
"IPv4Address": "10.0.1.37/24",
"IPv6Address": ""
}
通过下面的命令，找到这个命名空间的名字
vagrant@swarm-manager:~$ sudo ls /var/run/docker/netns/
1-14fy2l7a4m 1-lpirdge00y dfb766d83076 ingress_sbox lb_lpirdge00
vagrant@swarm-manager:~$
名字叫 lb_lpirdge00
通过nsenter进入到这个命名空间的sh里， 可以看到刚才的VIP地址10.0.1.30
vagrant@swarm-manager:~$ sudo nsenter --net=/var/run/docker/netns/lb_lpirdge00 sh
#
# ip a
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
50: eth0@if51: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1450 qdisc noqueue state UP group default
link/ether 02:42:0a:00:01:25 brd ff:ff:ff:ff:ff:ff link-netnsid 0
inet 10.0.1.37/24 brd 10.0.1.255 scope global eth0
valid_lft forever preferred_lft forever
inet 10.0.1.30/32 scope global eth0
valid_lft forever preferred_lft forever
inet 10.0.1.35/32 scope global eth0
valid_lft forever preferred_lft forever
#
和ingress网络一样，可以查看iptables，ipvs的负载均衡， 基本就可以理解负载均衡是怎么一回事了。 Mark=0x106, 也就是262（十进制），会轮询把请求发给10.0.1.31 和 10.0.1.32
# iptables -nvL -t mangle
Chain PREROUTING (policy ACCEPT 128 packets, 11198 bytes)
pkts bytes target prot opt in out source destination
Chain INPUT (policy ACCEPT 92 packets, 6743 bytes)
pkts bytes target prot opt in out source destination
72 4995 MARK all -- * * 0.0.0.0/0 10.0.1.30 MARK set 0x106
0 0 MARK all -- * * 0.0.0.0/0 10.0.1.35 MARK set 0x107
Chain FORWARD (policy ACCEPT 36 packets, 4455 bytes)
pkts bytes target prot opt in out source destination
Chain OUTPUT (policy ACCEPT 101 packets, 7535 bytes)
pkts bytes target prot opt in out source destination
Chain POSTROUTING (policy ACCEPT 128 packets, 11198 bytes)
pkts bytes target prot opt in out source destination
# ipvsadm
IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
-> RemoteAddress:Port Forward Weight ActiveConn InActConn
FWM 262 rr
-> 10.0.1.31:0 Masq 1 0 0
-> 10.0.1.32:0 Masq 1 0 0
FWM 263 rr
-> 10.0.1.36:0 Masq 1 0 0
#
这个流量会走我们的mynet这个overlay网络。
