How do i expose the Docker Remote API on Centos 7?

Question

On ubuntu i can go into /etc/init/docker.conf and put in DOCKER_OPTS='-H tcp://0.0.0.0:4243 -H unix:///var/run/docker.sock' to get the json data to display on my browser but how can i do it for Centos?

I have tried creating a file in /etc/sysconfig/docker and placing other_args="-H tcp://0.0.0.0:4243 -H unix:///var/run/docker.sock" inside the file and restarting docker but it doesn't do anything.

Solution

The systemd unit installed by the Docker corp package hardcodes the command line used to start the docker daemon:

[Service]
Type=notify
ExecStart=/usr/bin/dockerd
ExecReload=/bin/kill -s HUP $MAINPID
[...]

There is no support for reading a file from /etc/sysconfig or elsewhere to modify the command line. Fortunately, systemd gives us the tools we need to change this behavior.

The simplest solution is probably to create the file /etc/systemd/system/docker.service.d/docker-external.conf (the exact filename doesn't matter; it just needs to end with .conf) with the following contents:

[Service]
ExecStart=
ExecStart=/usr/bin/dockerd -H tcp://0.0.0.0:4243 -H unix:///var/run/docker.sock

And then:

systemctl daemon-reload
systemctl restart docker

This is actually documented on the Docker website in this document, which includes instructions for a more flexible solution that will allow you to use files in /etc/sysconfig to control the daemon.