How to increase docker disk image size in Ubuntu - docker

Question

I am trying to increase the docker image size on ubuntu. When I do docker info I get following info
Containers: 0
Running: 0
Paused: 0
Stopped: 0
Images: 0
Server Version: 17.09.0-ce
Storage Driver: overlay2
Backing Filesystem: extfs
Supports d_type: true
Native Overlay Diff: true
Logging Driver: json-file
Cgroup Driver: cgroupfs
Plugins:
Volume: local
Network: bridge host macvlan null overlay
Log: awslogs fluentd gcplogs gelf journald json-file logentries splunk syslog
Swarm: inactive
Runtimes: runc
Default Runtime: runc
Init Binary: docker-init
containerd version: 06b9cb35161009dcb7123345749fef02f7cea8e0
runc version: 3f2f8b84a77f73d38244dd690525642a72156c64
init version: 949e6fa
Security Options:
apparmor
seccomp
Profile: default
Kernel Version: 4.4.0-87-generic
Operating System: Ubuntu 16.04.3 LTS
OSType: linux
Architecture: x86_64
CPUs: 8
Total Memory: 15.67GiB
Name: no1010042033112.corp.adobe.com
ID: PYZE:KYTG:DXED:QI37:43ZM:56BB:TLM6:X2OJ:WDPA:35UP:Z4CU:DSNC
Docker Root Dir: /var/lib/docker
Debug Mode (client): false
Debug Mode (server): false
Registry: https://index.docker.io/v1/
Experimental: false
Insecure Registries:
127.0.0.0/8
Live Restore Enabled: false
As you can see that total memory is Total Memory: 15.67GiB. I couldn't find a way to do it on Ubuntu. I tried following ways
1) sudo dockerd --storage-opt dm.basesize=100G
2) Changing DOCKER_OPTS ="--storage-opt dm.basesize=50G" in /etc/default/docker.
But none of these helped. This option is easily available in Docker config in Windows. But how to do it from a ubuntu terminal

Answer 1

Docker, on Linux, with the overlay2 storage driver, uses all of the host system's disk (and memory). There's no way to make it use less disk (without repartitioning your main system disk) and no way to give it more (without adding new hardware).
Docker for Mac, the Linux-flavored Docker for Windows, and Docker Machine all work by launching virtual machines that run a minimal Linux OS. That VM has a specific disk and memory allocation and there's UI controls for it, but it's because the containers are running on a different OS and need an actual virtualization layer.
On Linux, Docker also supports several storage drivers. These require varying amounts of Linux kernel support. Early versions of Docker used something called devicemapper which worked by allocating space in (most often) a fixed-size file, and then the dm.basesize option you give matters ("dm" is for "devicemapper"). Current versions of Docker on current versions of Linux use a different driver called overlay2 which just stores image and container content in ordinary directories. You still need kernel support for it but there's no reserved or limited disk space. That's also why the only size number in the docker info output is memory, which is a different resource.