Find the SYSTEMD docker.service unit file. (Locate the directory where Docker.service is located)
Mine is located at:/usr/lib/systemd/system/docker.service
In Docker.service, you can see the following environment configuration files:
Environmentfile=-/etc/sysconfig/docker
Environmentfile=-/etc/sysconfig/docker-storage
Environmentfile=-/etc/sysconfig/docker-network
Storage-driven modifications on/etc/sysconfig/docker-storage
For example, I modified the overlay drive mode (requires CentOS kernel version 3.18.x above, and Docker version is newer, preferably more than 1.4)
Docker_storage_options= "--storage-driver=overlay"
Then dock info for a bit.
[Root@localhost default]# Docker Info
containers:0
images:0
Storage Driver:overlay
backing FILESYSTEM:XFS
Execution driver:native-0.2
Kernel version:4.1.2-1.el7.elrepo.x86_64
Operating System:centos Linux 7 (Core)
Cpus:4
Total memory:974.8 MiB
Name:localhost.localdomain
ID:PPG3:UCJG:ITPH:SFX5:MNMX:H3NH:LJET:KEK5:GNCC:VRKM:I5TS:PQY5
Docker modifies storage-driven mode on CentOS