初始化环境：（后面会返回到这个环境状态）
[root@localhost ~]# docker images REPOSITORY TAG IMAGE ID CREATED SIZE [root@localhost ~]# docker ps -a CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES我们尝试通过docker网桥方式（桥接）给一个容器设置一个ip地址（自定义的），下面看一下命令执行的结果：
[root@localhost ~]# docker run -itd --name test --network bridge --ip 172.17.0.10 CentOS:7 /bin/bash Unable to find image 'centos:7' locally 7: Pulling from library/centos ab5ef0e58194: Pull complete Digest: sha256:4a701376d03f6b39b8c2a8f4a8e499441b0d567f9ab9d58e4991de4472fb813c Status: Downloaded newer image for centos:7 29f9e9cbb398085d7c89bed2982d626bfb7e564371a76a6cb693cffa68b917af docker: Error response from daemon: user specified IP address is supported on user defined networks only.首先，由于没有改镜像，所以会先拉取镜像之后创建以及尝试运行容器，但是会遇到报错，报错原因是因为用户自己设置的ip地址只适合于他们自己定义的网络。但是这并不影响镜像的获取与创建，我们尝试运行看看结果：
[root@localhost ~]# docker images REPOSITORY TAG IMAGE ID CREATED SIZE centos 7 5e35e350aded 4 months ago 203MB [root@localhost ~]# docker ps -a CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 29f9e9cbb398 centos:7 "/bin/bash" About a minute ago Created test [root@localhost ~]# docker start 29f9e9cbb398 Error response from daemon: user specified IP address is supported on user defined networks only Error: failed to start containers: 29f9e9cbb398 很显然，结果告诉我们还是上述的原因导致了这个问题，好吧只能删除这个容器了。索性还原为初始化环境吧（其实可以去掉--network bridge就不会报错，但是设置的ip地址会不生效，可以自行尝试一下），我们不指定ip地址来试一下，顺便验证一下不加这个参数试试，最后还原为初始化状态后我们再通过自定义的方式来设置ip地址吧。
[root@localhost ~]# docker run -itd --name demo centos:7 /bin/bash 984545df8ebf2c30f4ccf3f5f4699ed67bd2a93cbc068f2ace4865a828b4a4d1 [root@localhost ~]# docker ps -a CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 984545df8ebf centos:7 "/bin/bash" 8 seconds ago Up 6 seconds demo进入容器查看ip地址
[root@localhost ~]# docker exec -it 984545df8ebf /bin/bash [root@984545df8ebf /]# yum install -y net-tools Loaded plugins: fastestmirror, ovl Determining fastest mirrors [root@984545df8ebf /]# ifconfig eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500 inet 172.17.0.2 netmask 255.255.0.0 broadcast 172.17.255.255 ether 02:42:ac:11:00:02 txqueuelen 0 (Ethernet) RX packets 2201 bytes 15042254 (14.3 MiB) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 1999 bytes 111171 (108.5 KiB) 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 loop txqueuelen 1000 (Local Loopback) RX packets 0 bytes 0 (0.0 B) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 0 bytes 0 (0.0 B) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0那么首先我们需要创建一个自定义的子网段，并且给他一个名称，通过这个网段给对应的容器设置固定的ip地址。
[root@localhost ~]# docker network create --subnet=172.18.0.0/24 mynetwork Error response from daemon: Failed to Setup IP tables: Unable to enable SKIP DNAT rule: (iptables failed: iptables --wait -t nat -I DOCKER -i br-4cd28c051bec -j RETURN: iptables: No chain/target/match by that name. (exit status 1))看来很不幸啊，又error了，不要慌，我们看看是什么原因导致的，这个报错的根源看似是防火墙，说是无法跳过DNAT（目标网络地址转换）规则，其实导致这个问题的原因是我们刚刚开启了防火墙，却没有重启docker服务，就有点类似更改了配置文件没有重启服务。
[root@localhost ~]# systemctl restart docker [root@localhost ~]# docker network create --subnet=172.18.0.0/24 mynetwork 723d0fd514eb219d57667f72c3eb75fc4864af0cd94c21b6c70e868fb8d520a1 [root@localhost ~]# docker network ls NETWORK ID NAME DRIVER SCOPE 00008a1e778b bridge bridge local 3bb2f50eb211 host host local 723d0fd514eb mynetwork bridge local e12cd7b98c54 none null local [root@localhost ~]#此时进行验证自定义设置一个容器的固定IP地址的测试：
[root@localhost ~]# docker run -itd --name test2 --network mynetwork --ip 172.18.0.10 centos:7 /bin/bash Unable to find image 'centos:7' locally 7: Pulling from library/centos ab5ef0e58194: Pull complete Digest: sha256:4a701376d03f6b39b8c2a8f4a8e499441b0d567f9ab9d58e4991de4472fb813c Status: Downloaded newer image for centos:7 683ad76f7789b5c16f251577047a288a3a4a00777128a216adfee15985b94c04