docker容器网络配置及常用操作

Linux内核实现名称空间的创建

ip netns（网络名称空间）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 ~]# rpm -qa|grep iproute
iproute-4.11.0-14.el7.x86_64
[root@localhost ~]# ip netns help
Usage: ip netns list        // 列出所有的名称空间
       ip netns add NAME    // 添加名称空间
       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

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

通过命令删除一个名为ns0的命名空间：

[root@localhost ~]# ip netns delete ns0

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

错误示范：手动创建一个名称空间（名称空间不可以手动去创建）

[root@localhost ~]# touch /var/run/netns/ns1
[root@localhost ~]# ip netns list
RTNETLINK answers: Invalid argument
RTNETLINK answers: Invalid argument
ns1
ns0

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 a     // 进入ns0这个名称空间里面去执行ip a这条命令
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

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: Network is unreachable

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 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
[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=0.033 ms
64 bytes from 127.0.0.1: icmp_seq=2 ttl=64 time=0.041 ms
64 bytes from 127.0.0.1: icmp_seq=3 ttl=64 time=0.032 ms

转移设备

我们可以在不同的 Network Namespace 之间转移设备（如veth）。由于一个设备只能属于一个 Network Namespace ，所以转移后在这个 Network Namespace 内就看不到这个设备了。

其中，veth设备属于可转移设备，而很多其它设备（如lo、vxlan、ppp、bridge等）是不可以转移的。

// 容器一运行，veth就会自动出现
[root@localhost ~]# docker run -it --rm busybox
/ # ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue 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
4: eth0@if5: <BROADCAST,MULTICAST,UP,LOWER_UP,M-DOWN> mtu 1500 qdisc noqueue 
    link/ether 02:42:ac:11:00:02 brd ff:ff:ff:ff:ff:ff
    inet 172.17.0.2/16 brd 172.17.255.255 scope global eth0
       valid_lft forever preferred_lft forever

[root@localhost ~]# ip a
........此处省略多行
5: veth693f9a1@if4: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master docker0 state UP group default 
    link/ether de:b2:5d:2a:ae:f7 brd ff:ff:ff:ff:ff:ff link-netnsid 0
    inet6 fe80::dcb2:5dff:fe2a:aef7/64 scope link 
       valid_lft forever preferred_lft forever

veth pair

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。
在这里插入图片描述

创建veth pair

[root@localhost ~]# ip link add type veth
[root@localhost ~]# ip link show
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP mode DEFAULT group default qlen 1000
    link/ether 00:0c:29:a8:8f:68 brd ff:ff:ff:ff:ff:ff
3: docker0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN mode DEFAULT group default 
    link/ether 02:42:13:af:55:08 brd ff:ff:ff:ff:ff:ff
6: veth0@veth1: <BROADCAST,MULTICAST,M-DOWN> mtu 1500 qdisc noop state DOWN mode DEFAULT group default qlen 1000
    link/ether c6:a1:94:ea:6e:75 brd ff:ff:ff:ff:ff:ff
7: veth1@veth0: <BROADCAST,MULTICAST,M-DOWN> mtu 1500 qdisc noop state DOWN mode DEFAULT group default qlen 1000
    link/ether 26:ae:e5:06:62:07 brd ff:ff:ff:ff:ff:ff

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 ns1
[root@localhost ~]# ip netns list
ns1
ns0

然后我们将veth0加入到ns0，将veth1加入到ns1

[root@localhost ~]# ip link set veth0 netns ns0
[root@localhost ~]# ip netns exec ns0 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
6: veth0@if7: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN group default qlen 1000
    link/ether c6:a1:94:ea:6e:75 brd ff:ff:ff:ff:ff:ff link-netnsid 0

[root@localhost ~]# ip link set veth1 netns ns1
[root@localhost ~]# ip netns exec ns1 ip a
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
7: veth1@if6: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN group default qlen 1000
    link/ether 26:ae:e5:06:62:07 brd ff:ff:ff:ff:ff:ff link-netnsid 0

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 ns0 ip link set veth0 up
[root@localhost ~]# ip netns exec ns0 ip addr add 10.0.0.1/24 dev veth0
[root@localhost ~]# ip netns exec ns1 ip link set lo up
[root@localhost ~]# ip netns exec ns1 ip link set veth1 up
[root@localhost ~]# ip netns exec ns1 ip addr add 10.0.0.2/24 dev veth1

查看这对veth pair的状态

[root@localhost ~]# ip netns exec ns0 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
6: veth0@if7: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
    link/ether c6:a1:94:ea:6e:75 brd ff:ff:ff:ff:ff:ff link-netnsid 1
    inet 10.0.0.1/24 scope global veth0
       valid_lft forever preferred_lft forever
    inet6 fe80::c4a1:94ff:feea:6e75/64 scope link 
       valid_lft forever preferred_lft forever

[root@localhost ~]# ip netns exec ns1 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
7: veth1@if6: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
    link/ether 26:ae:e5:06:62:07 brd ff:ff:ff:ff:ff:ff link-netnsid 0
    inet 10.0.0.2/24 scope global veth1
       valid_lft forever preferred_lft forever
    inet6 fe80::24ae:e5ff:fe06:6207/64 scope link 
       valid_lft forever preferred_lft forever

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 ns1 ping 10.0.0.1
PING 10.0.0.1 (10.0.0.1) 56(84) bytes of data.
64 bytes from 10.0.0.1: icmp_seq=1 ttl=64 time=0.065 ms
64 bytes from 10.0.0.1: icmp_seq=2 ttl=64 time=0.042 ms
64 bytes from 10.0.0.1: icmp_seq=3 ttl=64 time=0.050 ms

可以看到，veth pair成功实现了两个不同Network Namespace之间的网络交互。
如果跨越空间了，那么所有的属性都会被清掉。

[root@localhost ~]# ip netns add ns2
[root@localhost ~]# ip netns list
ns2
ns1
ns0
[root@localhost ~]# ip netns exec ns2 ip link set lo up
[root@localhost ~]# ip link set veth1 netns ns2
[root@localhost ~]# ip netns exec ns2 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
7: veth1@if6: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
    link/ether 56:85:95:f2:cc:11 brd ff:ff:ff:ff:ff:ff link-netnsid 0

veth设备重命名

[root@localhost ~]# ip netns exec ns0 ip link set veth0 down
[root@localhost ~]# ip netns exec ns0 ip link set dev veth0 name eth0
[root@localhost ~]# ip netns exec ns0 ip link set eth0 up
[root@localhost ~]# ip netns exec ns0 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
6: eth0@if7: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
    link/ether c6:a1:94:ea:6e:75 brd ff:ff:ff:ff:ff:ff link-netnsid 1
    inet 10.0.0.1/24 scope global eth0
       valid_lft forever preferred_lft forever
    inet6 fe80::c4a1:94ff:feea:6e75/64 scope link 
       valid_lft forever preferred_lft forever

[root@localhost ~]# ip netns exec ns1 ip link set veth1 down
[root@localhost ~]# ip netns exec ns1 ip link set dev veth1 name eth0
[root@localhost ~]# ip netns exec ns1 ip link set eth0 up
[root@localhost ~]# ip netns exec ns1 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
7: eth0@if6: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
    link/ether 26:ae:e5:06:62:07 brd ff:ff:ff:ff:ff:ff link-netnsid 0
    inet 10.0.0.2/24 scope global eth0
       valid_lft forever preferred_lft forever
    inet6 fe80::24ae:e5ff:fe06:6207/64 scope link 
       valid_lft forever preferred_lft forever

[root@localhost ~]# ip netns exec ns1 ping 10.0.0.1
PING 10.0.0.1 (10.0.0.1) 56(84) bytes of data.
64 bytes from 10.0.0.1: icmp_seq=1 ttl=64 time=0.046 ms
64 bytes from 10.0.0.1: icmp_seq=2 ttl=64 time=0.041 ms
64 bytes from 10.0.0.1: icmp_seq=3 ttl=64 time=0.100 ms

四种网络模式配置

bridge模式配置

[root@localhost ~]# docker run -it --rm busybox
/ # ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue 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
8: eth0@if9: <BROADCAST,MULTICAST,UP,LOWER_UP,M-DOWN> mtu 1500 qdisc noqueue 
    link/ether 02:42:ac:11:00:02 brd ff:ff:ff:ff:ff:ff
    inet 172.17.0.2/16 brd 172.17.255.255 scope global eth0
       valid_lft forever preferred_lft forever
/ # exit
[root@localhost ~]# docker container ls    // 查看运行容器

# 在创建容器时添加--network bridge与不加--network选项效果是一致的
[root@localhost ~]# docker run -it --rm --network bridge busybox
/ # ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue 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
10: eth0@if11: <BROADCAST,MULTICAST,UP,LOWER_UP,M-DOWN> mtu 1500 qdisc noqueue 
    link/ether 02:42:ac:11:00:02 brd ff:ff:ff:ff:ff:ff
    inet 172.17.0.2/16 brd 172.17.255.255 scope global eth0
       valid_lft forever preferred_lft forever
/ # exit

none模式配置

不用来通信，只用来做一些简单的操作

[root@localhost ~]# docker run -it --rm --network none busybox
/ # ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue 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
/ # exit

container模式配置

启动第一个容器

[root@localhost ~]# docker run -it --rm busybox
/ # ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue 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
12: eth0@if13: <BROADCAST,MULTICAST,UP,LOWER_UP,M-DOWN> mtu 1500 qdisc noqueue 
    link/ether 02:42:ac:11:00:02 brd ff:ff:ff:ff:ff:ff
    inet 172.17.0.2/16 brd 172.17.255.255 scope global eth0
       valid_lft forever preferred_lft forever

启动第二个容器

[root@localhost ~]# docker run -it --rm busybox
/ # ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue 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
14: eth0@if15: <BROADCAST,MULTICAST,UP,LOWER_UP,M-DOWN> mtu 1500 qdisc noqueue 
    link/ether 02:42:ac:11:00:03 brd ff:ff:ff:ff:ff:ff
    inet 172.17.0.3/16 brd 172.17.255.255 scope global eth0
       valid_lft forever preferred_lft forever

可以看到第二个容器的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，就可以使第二个容器的IP与第一个容器的IP一致，也即共享IP，但不共享文件系统。

[root@localhost ~]# docker run -it --rm --network container:72ae8bbf0c38 busybox
/ # ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue 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
12: eth0@if13: <BROADCAST,MULTICAST,UP,LOWER_UP,M-DOWN> mtu 1500 qdisc noqueue 
    link/ether 02:42:ac:11:00:02 brd ff:ff:ff:ff:ff:ff
    inet 172.17.0.2/16 brd 172.17.255.255 scope global eth0
       valid_lft forever preferred_lft forever
/ # hostname 
72ae8bbf0c38

此时我们在第一个容器上创建一个目录

/ # mkdir /tmp/data
/ # ls /tmp
data

到第二个容器上检查/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。

/ # ls
bin   dev   etc   home  proc  root  sys   tmp   usr   var

在第二个容器上部署一个站点

/ # ls /var/www/
/ # echo 'test page' > /var/www/index.html
/ # /bin/httpd/ -f -h /var/www/
sh: /bin/httpd/: not found
/ # /bin/httpd -f -h /var/www/

[root@localhost ~]# docker ps
CONTAINER ID   IMAGE     COMMAND   CREATED         STATUS         PORTS     NAMES
356a28d6a9fc   busybox   "sh"      4 minutes ago   Up 4 minutes             amazing_lichterman
72ae8bbf0c38   busybox   "sh"      9 minutes ago   Up 9 minutes             serene_wing
[root@localhost ~]# docker exec -it 356a28d6a9fc /bin/sh
/ # netstat -antl
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address           Foreign Address         State       
tcp        0      0 :::80                   :::*                    LISTEN      
/ # exit

在第一个容器上用本地地址去访问此站点

/ # wget -O - -q 127.0.0.1
test page

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 --rm --network host busybox
/ # ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue 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 qlen 1000
    link/ether 00:0c:29:a8:8f:68 brd ff:ff:ff:ff:ff:ff
    inet 192.168.35.135/24 brd 192.168.35.255 scope global dynamic noprefixroute ens33
       valid_lft 1256sec preferred_lft 1256sec
    inet6 fe80::c7db:4c9f:7bcc:55f5/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever
3: docker0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue 
    link/ether 02:42:13:af:55:08 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
    inet6 fe80::42:13ff:feaf:5508/64 scope link 
       valid_lft forever preferred_lft forever
/ # ip link show
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast qlen 1000
    link/ether 00:0c:29:a8:8f:68 brd ff:ff:ff:ff:ff:ff
3: docker0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue 
    link/ether 02:42:13:af:55:08 brd ff:ff:ff:ff:ff:ff

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。

[root@localhost ~]# ss -antl
State      Recv-Q Send-Q Local Address:Port               Peer Address:Port              
LISTEN     0      128     *:22                  *:*                  
LISTEN     0      100    127.0.0.1:25                  *:*                  
LISTEN     0      128    :::22                 :::*                  
LISTEN     0      100       ::1:25                 :::*   
          
/ # echo 'hello world' > /var/www/index.html
/ # /bin/httpd -f -h /var/www/

[root@localhost ~]# ss -antl
State      Recv-Q Send-Q Local Address:Port               Peer Address:Port              
LISTEN     0      128     *:22                  *:*                  
LISTEN     0      100    127.0.0.1:25                  *:*                  
LISTEN     0      9      :::80                 :::*                  
LISTEN     0      128    :::22                 :::*                  
LISTEN     0      100       ::1:25                 :::*

容器的常用操作

查看容器的主机名

[root@localhost ~]# docker run -it --rm busybox
/ # hostname 
68490a8f1c4e

在容器启动时注入主机名

[root@localhost ~]# docker run -it --rm --hostname lry busybox
/ # hostname 
lry
/ # cat /etc/hostname 
lry
/ # 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      lry      # 注入主机名时会自动创建主机名到IP的映射关系
/ # cat /etc/resolv.conf 
# Generated by NetworkManager
search localdomain
nameserver 192.168.35.2     # DNS也会自动配置为宿主机的DNS
/ # ping www.baidu.com
PING www.baidu.com (36.152.44.95): 56 data bytes
64 bytes from 36.152.44.95: seq=0 ttl=127 time=42.348 ms
64 bytes from 36.152.44.95: seq=1 ttl=127 time=44.581 ms
64 bytes from 36.152.44.95: seq=2 ttl=127 time=42.597 ms

手动指定容器要使用的DNS

[root@localhost ~]# docker run -it --rm --hostname lry --dns 114.114.114.114 busybox
/ # hostname 
lry
/ # cat /etc/resolv.conf 
search localdomain
nameserver 114.114.114.114
/ # nslookup -type=a www.baidu.com
Server:         114.114.114.114
Address:        114.114.114.114:53

Non-authoritative answer:
www.baidu.com   canonical name = www.a.shifen.com
Name:   www.a.shifen.com
Address: 36.152.44.96
Name:   www.a.shifen.com
Address: 36.152.44.95

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 --rm --hostname lry --dns 114.114.114.114 --add-host lry1:172.17.0.3 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
172.17.0.3      lry1
172.17.0.2      lry

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。

-p选项能够使用多次，其所能够暴露的端口必须是容器确实在监听的端口。

-p选项的使用格式：

-p <containerPort>
    将指定的容器端口映射至主机所有地址的一个动态端口
-p <hostPort>:<containerPort>
    将容器端口<containerPort>映射至指定的主机端口<hostPort>
-p <ip>::<containerPort>
    将指定的容器端口<containerPort>映射至主机指定<ip>的动态端口
-p <ip>:<hostPort>:<containerPort>
    将指定的容器端口<containerPort>映射至主机指定<ip>的端口<hostPort>

动态端口指的是随机端口，具体的映射结果可使用docker port命令查看。

第一种 - p 的使用方式

[root@localhost ~]# docker run -d --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
341c1ee1b9570401c48aab26ffb0cd9e0ac6149099bb9be25019bcc01f2549f9
[root@localhost ~]# docker ps
CONTAINER ID   IMAGE     COMMAND                  CREATED         STATUS         PORTS                                     NAMES
341c1ee1b957   nginx     "/docker-entrypoint.…"   5 seconds ago   Up 4 seconds   0.0.0.0:49153->80/tcp, :::49153->80/tcp   web

以上命令执行后会一直占用着前端，我们新开一个终端连接来看一下容器的80端口被映射到了宿主机的什么端口上

[root@localhost ~]# docker port web
80/tcp -> 0.0.0.0:49153
80/tcp -> :::49153

由此可见，容器的80端口被暴露到了宿主机的32769端口上，此时我们在宿主机上访问一下这个端口看是否能访问到容器内的站点

[root@localhost ~]# curl http://127.0.0.1:49154
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
html { color-scheme: light dark; }
body { width: 35em; margin: 0 auto;
font-family: Tahoma, Verdana, Arial, sans-serif; }
</style>
</head>
<body>
<h1>Welcome to nginx!</h1>
<p>If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.</p>

<p>For online documentation and support please refer to
<a href="http://nginx.org/">nginx.org</a>.<br/>
Commercial support is available at
<a href="http://nginx.com/">nginx.com</a>.</p>

<p><em>Thank you for using nginx.</em></p>
</body>
</html>

第二种 - p 的方式：

将容器端口映射到宿主机的指定端口

[root@localhost ~]# docker run -d --name web --rm -p 80:80 nginx   // 表示把容器里面的80映射到真机里面的80；前面80是真机的，后面80是容器的
5936ad37bb3e08877274991c88be899042eeba03555ea461e4ddda40e3e655b5

在另一个终端上查看端口映射情况

[root@localhost ~]# docker port web
80/tcp -> 0.0.0.0:80
80/tcp -> :::80

iptables防火墙规则将随容器的创建自动生成，随容器的删除自动删除规则。

第三种 - p 的方式：

将容器端口映射到指定IP的随机端口

[root@localhost ~]# docker run --name web --rm -p 192.168.35.135::80 nginx

在另一个终端上查看端口映射情况

[root@localhost ~]# docker port web
80/tcp -> 192.168.35.135:49153

第四种 - p 的方式：

将指定的容器端口映射至主机指定的端口

[root@localhost ~]# docker run -d --name web --rm -p 127.0.0.1:80:80 nginx
879c0985c813727208032f7dd1dd9b1a2570576cebc27ddf398c2df33e4252e0

在另一个终端上查看端口映射情况

[root@localhost ~]# docker port web
80/tcp -> 127.0.0.1:80

自定义docker0桥的网络属性信息

官方文档相关配置https://docs.docker.com/network/bridge/
自定义docker0桥的网络属性信息需要修改/etc/docker/daemon.json配置文件

[root@localhost ~]# vi /etc/docker/daemon.json 
{
  "registry-mirrors": ["https://2bkybiwf.mirror.aliyuncs.com"],
  "bip": "192.168.1.1/24"
}
[root@localhost ~]# systemctl restart docker

[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:a8:8f:68 brd ff:ff:ff:ff:ff:ff
    inet 192.168.35.135/24 brd 192.168.35.255 scope global noprefixroute dynamic ens33
       valid_lft 1169sec preferred_lft 1169sec
    inet6 fe80::c7db:4c9f:7bcc:55f5/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever
3: docker0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN group default 
    link/ether 02:42:5b:66:73:8e brd ff:ff:ff:ff:ff:ff
    inet 192.168.1.1/24 brd 192.168.1.255 scope global docker0
       valid_lft forever preferred_lft forever
    inet6 fe80::42:5bff:fe66:738e/64 scope link 
       valid_lft forever preferred_lft forever

核心选项为bip，即bridge ip之意，用于指定docker0桥自身的IP地址；其它选项可通过此地址计算得出。

docker远程连接(不常用)

dockerd守护进程的C/S，其默认仅监听Unix Socket格式的地址(/var/run/docker.sock)，如果要使用TCP套接字，则需要修改/etc/docker/daemon.json配置文件

docker创建自定义桥

创建一个额外的自定义桥，区别于docker0

[root@localhost ~]# docker network ls
NETWORK ID     NAME      DRIVER    SCOPE
bfef3a5a370d   bridge    bridge    local
6ceb6009fa51   host      host      local
722f6ab96f26   none      null      local
[root@localhost ~]# docker network create -d bridge --subnet "192.168.2.0/24" --gateway "192.168.2.1" br0
a298744eb8b168ee11c122a301dfd44d699c9cca7bfb9177944aae51fa7cef0e
[root@localhost ~]# docker network ls
NETWORK ID     NAME      DRIVER    SCOPE
a298744eb8b1   br0       bridge    local
bfef3a5a370d   bridge    bridge    local
6ceb6009fa51   host      host      local
722f6ab96f26   none      null      local

使用新创建的自定义桥来创建容器：

[root@localhost ~]# docker run -it --rm --network br0 busybox
/ # ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue 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
23: eth0@if24: <BROADCAST,MULTICAST,UP,LOWER_UP,M-DOWN> mtu 1500 qdisc noqueue 
    link/ether 02:42:c0:a8:02:02 brd ff:ff:ff:ff:ff:ff
    inet 192.168.2.2/24 brd 192.168.2.255 scope global eth0
       valid_lft forever preferred_lft forever

再创建一个容器，使用默认的bridge桥：

[root@localhost ~]# docker run -it --rm busybox
/ # ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue 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
25: eth0@if26: <BROADCAST,MULTICAST,UP,LOWER_UP,M-DOWN> mtu 1500 qdisc noqueue 
    link/ether 02:42:ac:11:00:02 brd ff:ff:ff:ff:ff:ff
    inet 172.17.0.2/16 brd 172.17.255.255 scope global eth0
       valid_lft forever preferred_lft forever

试想一下，此时的b2与b1能否互相通信？如果不能该如何实现通信？
在这里插入图片描述

/ # hostname 
bb1a030ba094

[root@localhost ~]# docker network connect br0 bb1a030ba094

/ # ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue 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
25: eth0@if26: <BROADCAST,MULTICAST,UP,LOWER_UP,M-DOWN> mtu 1500 qdisc noqueue 
    link/ether 02:42:ac:11:00:02 brd ff:ff:ff:ff:ff:ff
    inet 172.17.0.2/16 brd 172.17.255.255 scope global eth0
       valid_lft forever preferred_lft forever
27: eth1@if28: <BROADCAST,MULTICAST,UP,LOWER_UP,M-DOWN> mtu 1500 qdisc noqueue 
    link/ether 02:42:c0:a8:02:03 brd ff:ff:ff:ff:ff:ff
    inet 192.168.2.3/24 brd 192.168.2.255 scope global eth1
       valid_lft forever preferred_lft forever
/ # ping 192.168.2.2
PING 192.168.2.2 (192.168.2.2): 56 data bytes
64 bytes from 192.168.2.2: seq=0 ttl=64 time=0.204 ms
64 bytes from 192.168.2.2: seq=1 ttl=64 time=0.069 ms
64 bytes from 192.168.2.2: seq=2 ttl=64 time=0.079 ms