创建一个网络，网络指定IP运行容器报错，原因，docker中，只有使用 --subnet创建的网络才能指定静态IP
┌──[root@liruilongs.github.io]-[~]
└─$ docker network create load_balancing #创建一个网络
f9595e36d8a2fffd4e8570ad47439fa2a33864a357431c2abfad35d7d444c0c8
┌──[root@liruilongs.github.io]-[~]
└─$ docker run -itd -p 30000:80 --name=web1 --network=load_balancing --ip 172.18.0.2 httpd
3451c060c88b7d837d51ceab959d2faf805771a1b8e9ea2c186a91e4b492d3d8
docker: Error response from daemon: user specified IP address is supported only when connecting to networks with user configured subnets.