細述搭建docker之點到點的容器網絡

查看目前的網絡環境

[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

建立兩個無網絡的容器

--rm 參數講解一下：

在Docker容器退出時，默認容器內部的文件系統仍然被保留，以方便調試並保留用戶數據。

可是，對於foreground容器，因爲其只是在開發調試過程當中短時間運行，其用戶數據並沒有保留的必要，於是能夠在容器啓動時設置--rm選項，這樣在容器退出時就可以自動清理容器內部的文件系統。

--net=none 無網絡環境
--net=bridge 默認的參數，經過網橋（docker0）來設置容器的網絡。也能夠經過DOCKER_OPTS選項的-b參數來指定默認網橋
--net=host 共享主機的網絡環境，不推薦這麼設置
--net=container 兩個容器共享IP地址和端口號等網絡資源

下面兩個容器是在兩個終端中建立的

[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 /]#

查看這兩個容器的進程ID

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

爲這兩個容器建立虛擬的網絡空間

[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 ~]#

建立一對veth，兩端命名爲A、B

veth 是虛擬的以太設備，相似於網卡設備。這個是linux容器技術引進的，要求必須成對出現

[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

將兩端分別放到兩個容器中

咱們能夠看到，加入到容器以後，再次執行ip a 已經看不到這兩個設備了

[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

設置兩個容器網絡空間的ip

[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

啓動兩個容器的網絡

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

給這兩個容器設置一下網關

[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

測試

[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