After a couple of months of using Boot2Docker you can quickly produce a large number of images and containers.
$ docker images | wc -l
76
$ docker ps -a | wc -l
194
Each of these will be taking up valuable space on your drive. By default, boot2docker is only allocated a 18.2G disk so eventually when you attempt to build or pull new images it will fail due to running out of space.
The df command can be used after ssh’ing into the boot2docker VM to identify how much you have left. Boot2docker uses /mnt/sda1 for storing images and containers.
$ boot2docker ssh
$ df -h
Filesystem Size Used Available Use% Mounted on
rootfs 1.8G 203.5M 1.6G 11% /
tmpfs 1.8G 203.5M 1.6G 11% /
tmpfs 1004.2M 0 1004.2M 0% /dev/shm
/dev/sda1 18.2G 18.2G 0K 0% /mnt/sda1
cgroup 1004.2M 0 1004.2M 0% /sys/fs/cgroup
/dev/sda1 18.2G 18.2G 0K 0% /mnt/sda1/var/lib/docker/aufs
If you’ve ran out of space, one fix is to increase the size of the volume as described at https://docs.docker.com/articles/b2d_volume_resize/
The other, and potentially more sensible approach, is to perform some house keeping.
Firstly, to remove any exited containers you can use the command. Not this will remove any data inside the container unless it has been mounted as a separate volume.
$ docker ps -a -q | xargs -n 1 -I {} docker rm {}
The most space can be recovered by removing images, especially untagged images. Untagged images occurs when an image has been built but is only referred to via the latest tag. When a future image is built with the same name then the previous image is untagged as it’s no longer the latest version. If it hasn’t been tagged with another name then it will become untagged. Thanks to Mike Hadlow for the shell script to clean them up.
$ docker rmi $( docker images | grep '<none>' | tr -s ' ' | cut -d ' ' -f 3)
Another problem, as I’ve discussed in a previous blog post, is you might have downloaded more image tags than you expected via fig or docker pull. For example I accentially had 19 versions of redis on my local machine when I only needed one.
$ docker images | grep redis | wc -l
19
These are easily cleaned up by replacing <none> with the image names you want to remove.
$ docker rmi $( docker images | grep 'redis' | tr -s ' ' | cut -d ' ' -f 3)
Alternatively, if this is just too much hard work then simply burn it all and start again.
$ boot2docker destroy
$ boot2docker init