细述搭建docker之点到点的容器网络

[root@liuxin-test01 ~]# 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: eth0:  mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 00:0c:29:ca:41:84 brd ff:ff:ff:ff:ff:ff
    inet 192.168.8.192/24 brd 192.168.8.255 scope global eth0
       valid_lft forever preferred_lft forever
    inet6 fe80::20c:29ff:feca:4184/64 scope link
       valid_lft forever preferred_lft forever
3: eth1:  mtu 1500 qdisc noop state DOWN qlen 1000
    link/ether 00:0c:29:ca:41:8e brd ff:ff:ff:ff:ff:ff
4: docker0:  mtu 1500 qdisc noqueue state DOWN
    link/ether 02:42:a3:f4:2f:40 brd ff:ff:ff:ff:ff:ff
    inet 172.17.0.1/16 scope global docker0
       valid_lft forever preferred_lft forever
    inet6 fe80::42:a3ff:fef4:2f40/64 scope link
       valid_lft forever preferred_lft forever

--rm 参数讲解一下：

在Docker容器退出时，默认容器内部的文件系统仍然被保留，以方便调试并保留用户数据。

但是，对于foreground容器，由于其只是在开发调试过程中短期运行，其用户数据并无保留的必要，因而可以在容器启动时设置--rm选项，这样在容器退出时就能够自动清理容器内部的文件系统。

--net=none 无网络环境
--net=bridge 默认的参数，通过网桥（docker0）来设置容器的网络。也可以通过DOCKER_OPTS选项的-b参数来指定默认网桥
--net=host 共享主机的网络环境，不推荐这么设置
--net=container 两个容器共享IP地址和端口号等网络资源

下面两个容器是在两个终端中创建的

[root@liuxin-test01 ~]# docker run --rm -it --net=none --name='centos01' centos:7.4.1708
[root@f64cdc7ffff1 /]#
[root@liuxin-test01 ~]# docker run --rm -it --net=none --name='centos02' centos:7.4.1708
[root@cd4df383b68e /]#

[root@liuxin-test01 ~]# docker inspect -f '{{.State.Pid}}' f64
21682
[root@liuxin-test01 ~]# docker inspect -f '{{.State.Pid}}' cd4
21832

[root@liuxin-test01 ~]# mkdir -p /var/run/netns
[root@liuxin-test01 ~]# ln -s /proc/21682/ns/net /var/run/netns/21682
[root@liuxin-test01 ~]# ln -s /proc/21832/ns/net /var/run/netns/21832
[root@liuxin-test01 ~]#

veth 是虚拟的以太设备，类似于网卡设备。这个是linux容器技术引进的，要求必须成对出现

[root@liuxin-test01 ~]# ip link add A type veth peer name B
[root@liuxin-test01 ~]# 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: eth0:  mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 00:0c:29:ca:41:84 brd ff:ff:ff:ff:ff:ff
    inet 192.168.8.192/24 brd 192.168.8.255 scope global eth0
       valid_lft forever preferred_lft forever
    inet6 fe80::20c:29ff:feca:4184/64 scope link
       valid_lft forever preferred_lft forever
3: eth1:  mtu 1500 qdisc noop state DOWN qlen 1000
    link/ether 00:0c:29:ca:41:8e brd ff:ff:ff:ff:ff:ff
4: docker0:  mtu 1500 qdisc noqueue state DOWN
    link/ether 02:42:a3:f4:2f:40 brd ff:ff:ff:ff:ff:ff
    inet 172.17.0.1/16 scope global docker0
       valid_lft forever preferred_lft forever
    inet6 fe80::42:a3ff:fef4:2f40/64 scope link
       valid_lft forever preferred_lft forever
157: B@A:  mtu 1500 qdisc noop state DOWN qlen 1000
    link/ether de:f7:3b:24:a5:0e brd ff:ff:ff:ff:ff:ff
158: A@B:  mtu 1500 qdisc noop state DOWN qlen 1000
    link/ether 9a:65:96:de:04:90 brd ff:ff:ff:ff:ff:ff

我们可以看到，加入到容器之后，再次执行ip a 已经看不到这两个设备了

[root@liuxin-test01 ~]# ip link set A netns 21682
[root@liuxin-test01 ~]# ip link set B netns 21832
[root@liuxin-test01 ~]# 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: eth0:  mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 00:0c:29:ca:41:84 brd ff:ff:ff:ff:ff:ff
    inet 192.168.8.192/24 brd 192.168.8.255 scope global eth0
       valid_lft forever preferred_lft forever
    inet6 fe80::20c:29ff:feca:4184/64 scope link
       valid_lft forever preferred_lft forever
3: eth1:  mtu 1500 qdisc noop state DOWN qlen 1000
    link/ether 00:0c:29:ca:41:8e brd ff:ff:ff:ff:ff:ff
4: docker0:  mtu 1500 qdisc noqueue state DOWN
    link/ether 02:42:a3:f4:2f:40 brd ff:ff:ff:ff:ff:ff
    inet 172.17.0.1/16 scope global docker0
       valid_lft forever preferred_lft forever
    inet6 fe80::42:a3ff:fef4:2f40/64 scope link
       valid_lft forever preferred_lft forever

[root@liuxin-test01 ~]# ip netns exec 21682 ip addr add 192.168.99.1/32 dev A
[root@liuxin-test01 ~]# ip netns exec 21832 ip addr add 192.168.99.2/32 dev B

[root@liuxin-test01 ~]# ip netns exec 21682 ip link set A up
[root@liuxin-test01 ~]# ip netns exec 21832 ip link set B up

[root@liuxin-test01 ~]# ip netns exec 21682 ip route add 192.168.99.2/32 dev A
[root@liuxin-test01 ~]# ip netns exec 21832 ip route add 192.168.99.1/32 dev B

[root@f64cdc7ffff1 /]# ping 192.168.99.2
PING 192.168.99.2 (192.168.99.2) 56(84) bytes of data.
64 bytes from 192.168.99.2: icmp_seq=1 ttl=64 time=0.095 ms
[root@cd4df383b68e /]# ping 192.168.99.1
PING 192.168.99.1 (192.168.99.1) 56(84) bytes of data.
64 bytes from 192.168.99.1: icmp_seq=1 ttl=64 time=0.057 ms