docker容器网络配置_docker0:

Linux内核实现名称空间的创建

ip netns命令

可以借助ip netns命令来完成对 Network Namespace 的各种操作。ip netns命令来自于iproute安装包，一般系统会默认安装，如果没有的话，请自行安装。

注意：ip netns命令修改网络配置时需要 sudo 权限。

可以通过ip netns命令完成对Network Namespace 的相关操作，可以通过ip netns help查看命令帮助信息：

[root@localhost ~]# ip netn help
Usage: ip netns list
       ip netns add NAME
       ip netns set NAME NETNSID
       ip [-all] netns delete [NAME]
       ip netns identify [PID]
       ip netns pids NAME
       ip [-all] netns exec [NAME] cmd ...
       ip netns monitor
       ip netns list-id
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默认情况下，Linux系统中是没有任何 Network Namespace的，所以ip netns list命令不会返回任何信息。

创建Network Namespace

通过命令创建一个名为ns0的命名空间：

[root@localhost ~]# ip netns list
[root@localhost ~]# ip netns add ns0
[root@localhost ~]# ip netns list
ns0
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新创建的 Network Namespace 会出现在/var/run/netns/目录下。如果相同名字的 namespace 已经存在，命令会报Cannot create namespace file “/var/run/netns/ns0”: File exists的错误。

[root@localhost ~]# ls /var/run/netns/
ns0
[root@localhost ~]# ip netns add ns0
Cannot create namespace file "/var/run/netns/ns0": File exists
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对于每个 Network Namespace 来说，它会有自己独立的网卡、路由表、ARP 表、iptables 等和网络相关的资源。

操作Network Namespace

ip命令提供了ip netns exec子命令可以在对应的 Network Namespace 中执行命令。

查看新创建 Network Namespace 的网卡信息

[root@localhost ~]# ip netns exec ns0 ip addr
1: lo: <LOOPBACK> mtu 65536 qdisc noop state DOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
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可以看到，新创建的Network Namespace中会默认创建一个lo回环网卡，此时网卡处于关闭状态。此时，尝试去 ping 该lo回环网卡，会提示Network is unreachable

[root@localhost ~]# ip netns exec ns0 ping 127.0.0.1
connect: 网络不可达
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通过下面的命令启用lo回环网卡：

[root@localhost ~]# ip netns exec ns0 ip link set lo up
[root@localhost ~]# ip netns exec ns0 ping 127.0.0.1
PING 127.0.0.1 (127.0.0.1) 56(84) bytes of data.
64 bytes from 127.0.0.1: icmp_seq=1 ttl=64 time=0.057 ms
64 bytes from 127.0.0.1: icmp_seq=2 ttl=64 time=0.038 ms
64 bytes from 127.0.0.1: icmp_seq=3 ttl=64 time=0.039 ms
64 bytes from 127.0.0.1: icmp_seq=4 ttl=64 time=0.049 ms
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转移设备

veth pair 全称是 Virtual Ethernet Pair，是一个成对的端口，所有从这对端口一 端进入的数据包都将从另一端出来，反之也是一样。
引入veth pair是为了在不同的 Network Namespace 直接进行通信，利用它可以直接将两个 Network Namespace 连接起来。

创建veth pair

[root@localhost ~]# ip link add type veth
[root@localhost ~]# 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
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 00:0c:29:6a:14:f6 brd ff:ff:ff:ff:ff:ff
    inet 192.168.147.128/24 brd 192.168.147.255 scope global noprefixroute dynamic ens33
       valid_lft 1489sec preferred_lft 1489sec
    inet6 fe80::442d:8b15:917d:6db6/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever
3: virbr0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN group default qlen 1000
    link/ether 52:54:00:29:e0:4a brd ff:ff:ff:ff:ff:ff
    inet 192.168.122.1/24 brd 192.168.122.255 scope global virbr0
       valid_lft forever preferred_lft forever
4: virbr0-nic: <BROADCAST,MULTICAST> mtu 1500 qdisc pfifo_fast master virbr0 state DOWN group default qlen 1000
    link/ether 52:54:00:29:e0:4a brd ff:ff:ff:ff:ff:ff
5: docker0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN group default 
    link/ether 02:42:2e:5c:b1:d7 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
6: veth0@veth1: <BROADCAST,MULTICAST,M-DOWN> mtu 1500 qdisc noop state DOWN group default qlen 1000
    link/ether 82:65:ba:2e:57:da brd ff:ff:ff:ff:ff:ff
7: veth1@veth0: <BROADCAST,MULTICAST,M-DOWN> mtu 1500 qdisc noop state DOWN group default qlen 1000
    link/ether ba:78:ad:7a:aa:8b brd ff:ff:ff:ff:ff:ff
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可以看到，此时系统中新增了一对veth pair，将veth0和veth1两个虚拟网卡连接了起来，此时这对 veth pair 处于”未启用“状态。

实现Network Namespace间通信

下面我们利用veth pair实现两个不同的 Network Namespace 之间的通信。刚才我们已经创建了一个名为ns0的 Network Namespace，下面再创建一个信息Network Namespace，命名为ns1

[root@localhost ~]# ip netns add m1
[root@localhost ~]# 
[root@localhost ~]# ip netns list
m1
m2
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然后我们将veth0加入到ns0，将veth1加入到ns1

[root@localhost ~]# ip link set veth0 netns m1
[root@localhost ~]# ip link set veth1 netns m2
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然后我们分别为这对veth pair配置上ip地址，并启用它们

[root@localhost ~]# ip netns exec m1 ip link set veth0 up
[root@localhost ~]# ip netns exec m1 ip addr add 1.1.1.4/24 dev veth0
[root@localhost ~]# ip netns exec m2 ip link set lo up
[root@localhost ~]# ip netns exec m2 ip link set veth1 up
[root@localhost ~]# ip netns exec m2 ip addr add 1.1.1.5/24 dev veth1
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查看这对veth pair的状态

[root@localhost ~]# ip netns exec m1 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
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
8: veth0@if9: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
    link/ether 0a:0d:db:88:53:85 brd ff:ff:ff:ff:ff:ff link-netnsid 1
    inet 1.1.1.4/24 scope global veth0
       valid_lft forever preferred_lft forever
    inet6 fe80::80d:dbff:fe88:5385/64 scope link 
       valid_lft forever preferred_lft forever
[root@localhost ~]# ip netns exec m2 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
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
9: veth1@if8: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
    link/ether b2:4c:ab:92:75:e1 brd ff:ff:ff:ff:ff:ff link-netnsid 0
    inet 1.1.1.5/24 scope global veth1
       valid_lft forever preferred_lft forever
    inet6 fe80::b04c:abff:fe92:75e1/64 scope link 
       valid_lft forever preferred_lft forever
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从上面可以看出，我们已经成功启用了这个veth pair，并为每个veth设备分配了对应的ip地址。我们尝试在ns1中访问ns0中的ip地址：

[root@localhost ~]# ip netns exec m2 ping 1.1.1.4
PING 1.1.1.4 (1.1.1.4) 56(84) bytes of data.
64 bytes from 1.1.1.4: icmp_seq=1 ttl=64 time=0.077 ms
64 bytes from 1.1.1.4: icmp_seq=2 ttl=64 time=0.056 ms
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可以看到，veth pair成功实现了两个不同Network Namespace之间的网络交互。

veth设备重命名

[root@localhost ~]# ip netns exec m1 ifconfig -a
eth0: flags=4098<BROADCAST,MULTICAST>  mtu 1500
        inet 1.1.1.4  netmask 255.255.255.0  broadcast 0.0.0.0
        ether 0a:0d:db:88:53:85  txqueuelen 1000  (Ethernet)
        RX packets 12  bytes 928 (928.0 B)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 12  bytes 928 (928.0 B)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536
        inet 127.0.0.1  netmask 255.0.0.0
        inet6 ::1  prefixlen 128  scopeid 0x10<host>
        loop  txqueuelen 1000  (Local Loopback)
        RX packets 4  bytes 336 (336.0 B)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 4  bytes 336 (336.0 B)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
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四种网络模式配置

bridge模式配置

[root@localhost ~]# docker run -it --name test1 --rm busybox
/ # ifconfig 
eth0      Link encap:Ethernet  HWaddr 02:42:AC:11:00:02  
          inet addr:172.17.0.2  Bcast:172.17.255.255  Mask:255.255.0.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:20 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:2338 (2.2 KiB)  TX bytes:0 (0.0 B)

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          UP LOOPBACK RUNNING  MTU:65536  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)

/ # exit
# 在创建容器时添加--network bridge与不加--network选项效果是一致的
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none模式配置

[root@localhost ~]# docker run -it --name test --network none --rm busybox
/ # ifconfig -a
lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          UP LOOPBACK RUNNING  MTU:65536  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)

/ # exit
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container模式配置

启动第一个容器

[root@localhost ~]# docker run -it --name test1 --rm busybox
/ # ifconfig 
eth0      Link encap:Ethernet  HWaddr 02:42:AC:11:00:02  
          inet addr:172.17.0.2  Bcast:172.17.255.255  Mask:255.255.0.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:6 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:508 (508.0 B)  TX bytes:0 (0.0 B)

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          UP LOOPBACK RUNNING  MTU:65536  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)

/ #
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启动第二个容器

[root@localhost ~]# docker run -it --name test2 --rm busybox
/ # ifconfig 
eth0      Link encap:Ethernet  HWaddr 02:42:AC:11:00:03  
          inet addr:172.17.0.3  Bcast:172.17.255.255  Mask:255.255.0.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:6 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:508 (508.0 B)  TX bytes:0 (0.0 B)

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          UP LOOPBACK RUNNING  MTU:65536  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)

/ #
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可以看到名为test2的容器IP地址是172.17.0.3，与第一个容器的IP地址不是一样的，也就是说并没有共享网络，此时如果我们将第二个容器的启动方式改变一下，就可以使名为b2的容器IP与B1容器IP一致，也即共享IP，但不共享文件系统。

[root@localhost ~]# docker run -it --name test2 --rm --network container:test1 busybox
/ # ifconfig 
eth0      Link encap:Ethernet  HWaddr 02:42:AC:11:00:02  
          inet addr:172.17.0.2  Bcast:172.17.255.255  Mask:255.255.0.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:8 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:648 (648.0 B)  TX bytes:0 (0.0 B)

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          UP LOOPBACK RUNNING  MTU:65536  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)

/ # 
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此时我们在test1容器上创建一个目录

/ # mkdir /tmp/data
/ # ls /tmp/
data
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到test2容器上检查/tmp目录会发现并没有这个目录，因为文件系统是处于隔离状态，仅仅是共享了网络而已。
在test2容器上部署一个站点

/ # echo 'Welcome' > /tmp/index.html
/ # ls /tmp/
index.html
/ # httpd -h /tmp/
/ # netstat -anlt
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address           Foreign Address         State       
tcp        0      0 :::80                   :::*                    LISTEN      
/ #
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在test1容器上用本地地址去访问此站点

/ # wget -O - -q 127.0.0.1:80
Welcome
/ #
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由此可见，container模式下的容器间关系就相当于一台主机上的两个不同进程

host模式配置

启动容器时直接指明模式为host

[root@localhost ~]# docker run -it --name test --rm --network host busybox
/ # ifconfig 
docker0   Link encap:Ethernet  HWaddr 02:42:2E:5C:B1:D7  
          inet addr:172.17.0.1  Bcast:172.17.255.255  Mask:255.255.0.0
          inet6 addr: fe80::42:2eff:fe5c:b1d7/64 Scope:Link
          UP BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:13 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:0 (0.0 B)  TX bytes:1760 (1.7 KiB)

ens33     Link encap:Ethernet  HWaddr 00:0C:29:6A:14:F6  
          inet addr:192.168.147.128  Bcast:192.168.147.255  Mask:255.255.255.0
          inet6 addr: fe80::442d:8b15:917d:6db6/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:53902 errors:0 dropped:0 overruns:0 frame:0
          TX packets:75202 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:4693616 (4.4 MiB)  TX bytes:20161459 (19.2 MiB)

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:65536  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)

virbr0    Link encap:Ethernet  HWaddr 52:54:00:29:E0:4A  
          inet addr:192.168.122.1  Bcast:192.168.122.255  Mask:255.255.255.0
          UP BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)

/ #
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此时如果我们在这个容器中启动一个http站点，我们就可以直接用宿主机的IP直接在浏览器中访问这个容器中的站点了。

容器的常用操作

查看容器的主机名

[root@localhost ~]# docker run -it --name test1 --network bridge --rm busybox
/ # hostname
5fc058523ad1
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在容器启动时注入主机名

[root@localhost ~]# docker run -it --name test --network bridge --hostname mkf --rm busybox
/ # hostname
mkf
/ # cat /etc/hosts
127.0.0.1       localhost
::1     localhost ip6-localhost ip6-loopback
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters
172.17.0.2      mkf
/ # cat /etc/resolv.conf 
# Generated by NetworkManager
search localdomain
nameserver 192.168.147.2
/ # ping baidu.com
PING baidu.com (220.181.38.148): 56 data bytes
64 bytes from 220.181.38.148: seq=0 ttl=127 time=28.901 ms
64 bytes from 220.181.38.148: seq=1 ttl=127 time=28.912 ms
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手动指定容器要使用的DNS

[root@localhost ~]# docker run -it --name test --network bridge --hostname mkf --dns 8.8.8.8 --rm busybox
/ # cat /etc/resolv.conf 
search localdomain
nameserver 8.8.8.8
/ # nslookup -type=a baidu.com
Server:         8.8.8.8
Address:        8.8.8.8:53

Non-authoritative answer:
Name:   baidu.com
Address: 220.181.38.148
Name:   baidu.com
Address: 220.181.38.251
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手动往/etc/hosts文件中注入主机名到IP地址的映射

[root@localhost ~]# docker run -it --name test --network bridge --hostname mokaifu --add-host www.mkf.com:1.1.1.1 --rm busybox
/ # cat /etc/hosts 
127.0.0.1       localhost
::1     localhost ip6-localhost ip6-loopback
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters
1.1.1.1 www.mkf.com
172.17.0.2      mokaifu
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开放容器端口

执行docker run的时候有个-p选项，可以将容器中的应用端口映射到宿主机中，从而实现让外部主机可以通过访问宿主机的某端口来访问容器内应用的目的。

[root@localhost ~]# docker run --name web --rm -p 80 nginx
Unable to find image 'nginx:latest' locally
latest: Pulling from library/nginx
e5ae68f74026: Pull complete 
21e0df283cd6: Pull complete 
ed835de16acd: Pull complete 
881ff011f1c9: Pull complete 
77700c52c969: Pull complete 
44be98c0fab6: Pull complete 
Digest: sha256:9522864dd661dcadfd9958f9e0de192a1fdda2c162a35668ab6ac42b465f0603
Status: Downloaded newer image for nginx:latest
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