sudo vi /etc/docker/daemon.json

{
  "registry-mirrors": ["http://hub-mirror.c.163.com"]
}

root@ubuntu:~# docker info
Client:
 Debug Mode: false

Server:
 Containers: 3
 Running: 0
 Paused: 0
 Stopped: 3
 Images: 3
 Server Version: 19.03.8
 Storage Driver: overlay2
 Backing Filesystem: <unknown>
 Supports d_type: true
 Native Overlay Diff: true
 Logging Driver: json-file
 Cgroup Driver: cgroupfs
 Plugins:
 Volume: local
 Network: bridge host ipvlan macvlan null overlay
 Log: awslogs fluentd gcplogs gelf journald json-file local logentries splunk syslog
 Swarm: inactive
 Runtimes: runc
 Default Runtime: runc
 Init Binary: docker-init
 containerd version: 7ad184331fa3e55e52b890ea95e65ba581ae3429
 runc version: dc9208a3303feef5b3839f4323d9beb36df0a9dd
 init version: fec3683
 Security Options:
 apparmor
 seccomp
  Profile: default
 Kernel Version: 4.15.0-97-generic
 Operating System: Ubuntu 18.04.4 LTS
 OSType: linux
 Architecture: x86_64
 CPUs: 12
 Total Memory: 7.767GiB
 Name: ubuntu
 ID: 2XV6:BJ7Q:6BIH:4FIR:HEPL:3GF7:33A2:GGTU:EQMB:EKGX:EO34:5J44
 Docker Root Dir: /var/lib/docker
 Debug Mode: false
 Registry: https://index.docker.io/v1/
 Labels:
 Experimental: false
 Insecure Registries:
 127.0.0.0/8
 Registry Mirrors:
 http://hub-mirror.c.163.com/
 Live Restore Enabled: false

WARNING: No swap limit support