Docker is great but sometimes the images that are used are rather large on the disk.

The following commands can be used to investigate how much space various containers are actually using on your disk.

How to list docker files and how big they are

$ docker system df -v

Note: It is important to look at the shared and non shared space so you know how much an individual container is using.

Example output

REPOSITORY TAG IMAGE ID CREATED ago SIZE SHARED SIZE UNIQUE SiZE CONTAINERS
quay.io/sameersbn/redis latest 57075594a27a 12 days ago ago 202.1MB 0B 202.1MB 1
jenkins latest 0b4d4d677a26 6 weeks ago ago 681.2MB 0B 681.2MB 1
ubuntu 17.04 49d40961099d 2 months ago ago 91.79MB 0B 91.79MB 0
ubuntu 16.04 7b9b13f7b9c0 2 months ago ago 118.3MB 0B 118.3MB 0
pu4 latest 0573cc18b58b 2 months ago ago 2.533GB 2.44GB 93.13MB 0
arm-gcc latest dd52e75f13bd 2 months ago ago 2.44GB 2.44GB 0B 0
portainer/portainer latest f11b231ae3e9 2 months ago ago 10.21MB 0B 10.21MB 4
pycharm_helpers PY-172.2103.19 438b81184b8d 2 months ago ago 25.87MB 0B 25.87MB 1
mono latest e4a9afed02d5 2 months ago ago 580.3MB 0B 580.3MB 0
registry 2 9d0c4eabab4d 2 months ago ago 33.2MB 0B 33.2MB 1
simulator-compiler latest 4df74408889e 3 months ago ago 2.298GB 2.296GB 2.736MB 0
<none> <none> a898db8020d6 3 months ago ago 2.298GB 2.296GB 2.67MB 0
<none> <none> 906a8f803338 3 months ago ago 1.727GB 228.9MB 1.498GB 0
<none> <none> 3fdadf386cfb 3 months ago ago 1.651GB 776.1MB 874.8MB 0
<none> <none> 35a194f98ba8 3 months ago ago 779.9MB 776.1MB 3.797MB 0
display-runner latest 1ce1dd2629f5 3 months ago ago 754MB 705.3MB 48.68MB 0
<none> <none> 36cdf943d844 3 months ago ago 714.3MB 0B 714.3MB 5
<none> <none> 3ceba3c6b088 3 months ago ago 753.9MB 751.2MB 2.67MB 0
<none> <none> 6cff4d19bc95 3 months ago ago 753MB 751.2MB 1.718MB 0

How to see dangling images

Dangling images are images with no container name.

$ docker images -f dangling=true

How to remove dangling images

$ docker rmi $(docker images -f dangling=true -q)