How to change docker daemon root directory in CentOS7

Question

I am running docker in CentOS7.

I'd like to change my basic directory from /var/lib/docker to /data/docker.

I found this guide from official site, but do not know how to apply this to my case.

I just make new daemon.json in /etc/docker/. After that when I am trying to run daemon occurs an error.

follow is systemctl status -l docker.service.

● docker.service - Docker Application Container Engine
   Loaded: loaded (/usr/lib/systemd/system/docker.service; disabled; vendor preset: disabled)
   Active: failed (Result: exit-code) since Thu 2017-04-27 15:07:41 KST; 47s ago
     Docs: https://docs.docker.com
  Process: 42547 ExecStart=/usr/bin/dockerd (code=exited, status=1/FAILURE)
 Main PID: 42547 (code=exited, status=1/FAILURE)

Apr 27 15:07:41 DCSF-DEV08 systemd[1]: Starting Docker Application Container Engine...
Apr 27 15:07:41 DCSF-DEV08 dockerd[42547]: unable to configure the Docker daemon with file /etc/docker/daemon.json: the following directives don't match any configuration option: default-ulimits
Apr 27 15:07:41 DCSF-DEV08 systemd[1]: docker.service: main process exited, code=exited, status=1/FAILURE
Apr 27 15:07:41 DCSF-DEV08 systemd[1]: Failed to start Docker Application Container Engine.
Apr 27 15:07:41 DCSF-DEV08 systemd[1]: Unit docker.service entered failed state.
Apr 27 15:07:41 DCSF-DEV08 systemd[1]: docker.service failed.

So how could I fix this?(And I would like to know what is default setting for daemon when I just run systemctl start docker without /etc/docker/daemon.json)

========= EDIT ===================

My current docker daemon.js.

{
    "api-cors-header": "",
    "authorization-plugins": [],
    "bip": "",
    "bridge": "",
    "cgroup-parent": "",
    "cluster-store": "",
    "cluster-store-opts": {},
    "cluster-advertise": "",
    "debug": true,
    "default-gateway": "",
    "default-gateway-v6": "",
    "default-runtime": "runc",
    "default-ulimits": {},
    "disable-legacy-registry": false,
    "dns": [],
    "dns-opts": [],
    "dns-search": [],
    "exec-opts": [],
    "exec-root": "",
    "fixed-cidr": "",
    "fixed-cidr-v6": "",
    "graph": "/data/docker",
    "group": "",
    "hosts": [],
    "icc": false,
    "insecure-registries": [],
    "ip": "0.0.0.0",
    "iptables": false,
    "ipv6": false,
    "ip-forward": false,
    "ip-masq": false,
    "labels": [],
    "live-restore": true,
    "log-driver": "",
    "log-level": "",
    "log-opts": {},
    "max-concurrent-downloads": 3,
    "max-concurrent-uploads": 5,
    "mtu": 0,
    "oom-score-adjust": -500,
    "pidfile": "",
    "raw-logs": false,
    "registry-mirrors": [],
    "runtimes": {
        "runc": {
            "path": "runc"
        },
        "custom": {
            "path": "/usr/local/bin/my-runc-replacement",
            "runtimeArgs": [
                "--debug"
            ]
        }
    },
    "selinux-enabled": false,
    "storage-driver": "",
    "storage-opts": [],
    "swarm-default-advertise-addr": "",
    "tls": true,
    "tlscacert": "",
    "tlscert": "",
    "tlskey": "",
    "tlsverify": true,
    "userland-proxy": false,
    "userns-remap": ""
}

The only thing I changed is graph, since I just want to change root directory. (I want to put others as default. default means same configuration as systemctl start docker)

Answer 1

Edit /etc/docker/daemon.json.

Put only the following content:

{
    "data-root": "/data/docker"
}

Restart docker daemon: sudo service docker restart

For Json MetaData Refer: daemon.json from Docker documentation

Answer 2

It is possible to change docker root directory by creating a systemd drop-in service file. This is useful when you want images and containers or docker generated files to be located in another partition or drive.

More information on this article :
https://medium.com/@wlarch/change-docker-root-directory-by-creating-a-systemd-drop-in-service-file-3c1244244784