前言：查了很多网上资料 都说要修改daemons,json 完全不管用，而且还导致添加
{
“host”:["tcp://0.0.0.0:2375","unix:///var/lib/docker.sock"]
}后，docker restart 失败，浪费了不少时间 ！！！
下边的方式是测试没问题的，记录分享一下。
默认安装的Docker服务是不支持远程连接的，开启TCP端口后可以进行远程连接Docker
1、操作系统环境：ubuntu 18.4
2、编辑 docker 服务
注释原有 ExecStart 参数，新增 ExecStart 参数，见加红色字体。
注意是在“/lib/systemd/system/”目录下，网上很多人路径是“/usr/lib/systemd/”进去你会发现并没有system目录何况docker.service了
[root@localhost home]# vi /lib/systemd/system/docker.service
[Unit]
Description=Docker Application Container Engine
Documentation=https://docs.docker.com
After=network-online.target firewalld.service
Wants=network-online.target[Service]
Type=notify
# the default is not to use systemd for cgroups because the delegate issues still
# exists and systemd currently does not support the cgroup feature set required
# for containers run by docker
# ExecStart=/usr/bin/dockerd
ExecStart=/usr/bin/dockerd -H unix:///var/run/docker.sock -H tcp://0.0.0.0:2375
ExecReload=/bin/kill -s HUP $MAINPID
# Having non-zero Limit*s causes performance problems due to accounting overhead
# in the kernel. We recommend using cgroups to do container-local accounting.
LimitNOFILE=infinity
LimitNPROC=infinity
LimitCORE=infinity
# Uncomment TasksMax if your systemd version supports it.
# Only systemd 226 and above support this version.
#TasksMax=infinity
TimeoutStartSec=0
# set delegate yes so that systemd does not reset the cgroups of docker containers
Delegate=yes
# kill only the docker process, not all processes in the cgroup
KillMode=process
# restart the docker process if it exits prematurely
Restart=on-failure
StartLimitBurst=3
StartLimitInterval=60s[Install]
WantedBy=multi-user.target
-H代表指定docker的监听方式，这里是socket文件位置，也就是socket方式，2375就是tcp端口
3、保存退出
4、重新加载系统服务配置文件
systemctl daemon-reload
5、重启 docker 服务
systemctl restart docker
6、查看监听端口
netstat -nplt | grep 2375
