Docker disk memory : can I remove intermediate images? - docker

Question

I'm running out of disk memory.
If I run docker images, I get a lot of results:
app_mongodb latest 355f8f37c385 17 hours ago 568.1 MB
app_web latest a31db2244a8b 18 hours ago 868.2 MB
<none> <none> 71e586165d46 18 hours ago 568.1 MB
<none> <none> 422c281541d3 18 hours ago 568.1 MB
<none> <none> 1b16da634fa1 18 hours ago 535.4 MB
website_web latest e4442589e2f4 2 days ago 793.6 MB
<none> <none> 5445f9b915e6 3 days ago 535.4 MB
<none> <none> e825b94d5938 3 days ago 868 MB
<none> <none> ea1ddc53d17f 3 days ago 535.4 MB
<none> <none> 90531b8bd2d3 5 days ago 855.6 MB
<none> <none> 774895648397 5 days ago 535.4 MB
<none> <none> 0f474dc179c4 5 days ago 855.6 MB
<none> <none> 37cd4d180580 5 days ago 535.4 MB
<none> <none> 5f701c2e3fac 5 days ago 535.4 MB
<none> <none> 6837158ac191 5 days ago 535.4 MB
<none> <none> f3eecd70620e 5 days ago 535.4 MB
<none> <none> 27b3e1701f05 5 days ago 535.4 MB
<none> <none> 64763f09b1d4 5 days ago 535.4 MB
<none> <none> b58542e468e6 5 days ago 855.6 MB
app2_web latest 01c45018b686 5 days ago 645.5 MB
redis latest e4a35914679d 11 days ago 182.9 MB
<none> <none> 8d6737f884f8 12 days ago 854.7 MB
<none> <none> 27f7742e8b2b 2 weeks ago 792.1 MB
api_web latest 59ec56265675 2 weeks ago 906.4 MB
<none> <none> 33c328f5a271 2 weeks ago 782.2 MB
<none> <none> 53d4ad25e6c2 2 weeks ago 782.1 MB
<none> <none> 01ac14f597ba 2 weeks ago 854 MB
app3_web latest 2aaa4675cc58 3 weeks ago 929.9 MB
<none> <none> bde15910281e 3 weeks ago 789.5 MB
postgres latest ecd991538a0f 4 weeks ago 265.5 MB
app4_web latest c8b0de070d78 7 weeks ago 1.088 GB
<none> <none> 67e3ef67081b 7 weeks ago 859.2 MB
<none> <none> 451229f8dedb 7 weeks ago 859.2 MB
server_web latest 72bd5165f262 9 weeks ago 665.4 MB
<none> <none> c7f0d2b67986 9 weeks ago 660.9 MB
app5_web latest 7477b8e5ef63 3 months ago 690 MB
<none> <none> ee7de82e0cf0 3 months ago 856.7 MB
mdillon/postgis latest ee2a84576d15 3 months ago 600.2 MB
<none> <none> d8ee634a8581 4 months ago 685.3 MB
memcached latest 5fdd5c36cc9a 4 months ago 126.1 MB
app6_web latest 813fb5eac7d1 5 months ago 823.7 MB
app7_web latest 3b6a87b67359 5 months ago 645.5 MB
node argon 3b6a87b67359 5 months ago 645.5 MB
mongo latest 48b8b08dca4d 6 months ago 366.4 MB
ruby 2.2.1 aca1c061bdd2 23 months ago 775.1 MB
I know what all the named dockers correspond to, I can easily manage them and remove those I don't need anymore. But they are not majority!
Regarding the other ones, I guess they are intermediate dockers.
I wonder if I remove those, will the named one be broken or it's simply that if I rebuild them (eg. with the --no-cache option), docker will have to re-download them? (which is fine)
Eg. Does a docker based on the ruby one needs it to start or only to build?

Answer 1

These are probably images you built in the past, but then when you rebuilt the image, the relevant tag moved to another image, leaving these images untagged. Thus they show up as <none> <none>.
Looking at a sampling of your output, I'd guess a lot of them are old builds of app_mongodb:latest and app_web:latest. Based on the sizes.
app_mongodb latest 355f8f37c385 17 hours ago 568.1 MB
app_web latest a31db2244a8b 18 hours ago 868.2 MB
<none> <none> 71e586165d46 18 hours ago 568.1 MB
<none> <none> 422c281541d3 18 hours ago 568.1 MB
<none> <none> 1b16da634fa1 18 hours ago 535.4 MB
website_web latest e4442589e2f4 2 days ago 793.6 MB
<none> <none> 5445f9b915e6 3 days ago 535.4 MB
<none> <none> e825b94d5938 3 days ago 868 MB
<none> <none> ea1ddc53d17f 3 days ago 535.4 MB
<none> <none> 90531b8bd2d3 5 days ago 855.6 MB
<none> <none> 774895648397 5 days ago 535.4 MB
<none> <none> 0f474dc179c4 5 days ago 855.6 MB
<none> <none> 37cd4d180580 5 days ago 535.4 MB
<none> <none> 5f701c2e3fac 5 days ago 535.4 MB
<none> <none> 6837158ac191 5 days ago 535.4 MB
<none> <none> f3eecd70620e 5 days ago 535.4 MB
<none> <none> 27b3e1701f05 5 days ago 535.4 MB
<none> <none> 64763f09b1d4 5 days ago 535.4 MB
<none> <none> b58542e468e6 5 days ago 855.6 MB
It is most likely safe to delete them. If you try to delete them and they are being used by a container or another image, then Docker will complain about that.
In recent versions of Docker (I believe >= 1.13) you can use the prune command to clean up images not referenced by an image or container.
docker image prune

Answer 2

in the newer docker versions, you can simply do:
docker image prune
refer to: https://docs.docker.com/engine/reference/commandline/image_prune/#description

Answer 3

Using docker images -f dangling=true -q we can find <none><none> images. Then we can delete them using below command,
docker rmi -f $(docker images -f dangling=true -q --no-trunc)
We may need -f option to delete them forcefully.