Prune unused Docker objects
Docker takes a conservative approach to cleaning up unused objects (often referred to as
“garbage collection”), such as images, containers, volumes, and networks: these objects are
generally not removed unless you explicitly ask Docker to do so. This can cause Docker to use
extra disk space. For each type of object, Docker provides a prune command. In addition, you
can use docker system prune to clean up multiple types of objects at once. This topic shows
how to use these prune commands.
Prune images
The docker image prune command allows you to clean up unused images. By default, docker
image prune only cleans up dangling images. A dangling image is one that is not tagged and is
not referenced by any container. To remove dangling images:
$ docker image prune
To remove all images which are not used by existing containers, use the -a flag:
$ docker image prune -a
By default, you are prompted to continue. To bypass the prompt, use the -f or –force flag.
You can limit which images are pruned using filtering expressions with the –filter flag. For
example, to only consider images created more than 24 hours ago:
$ docker image prune -a –filter “until=24h”
for more options:
https://docs.docker.com/engine/reference/commandline/image_prune/
Prune containers
When you stop a container, it is not automatically removed unless you started it with the –rm
flag. To see all containers on the Docker host, including stopped containers, use docker ps -a.
You may be surprised how many containers exist, especially on a development system! A
stopped container’s writable layers still take up disk space. To clean this up, you can use the
docker container prune command.
$ docker container prune
By default, you are prompted to continue. To bypass the prompt, use the -f or –force flag.
By default, all stopped containers are removed. You can limit the scope using the –filter flag.
For instance, the following command only removes stopped containers older than 24 hours:
$ docker container prune –filter “until=24h”
for more options https://docs.docker.com/engine/reference/commandline/container_prune/
Prune volumes
Volumes can be used by one or more containers, and take up space on the Docker host.
Volumes are never removed automatically, because to do so could destroy data.
$ docker volume prune
By default, you are prompted to continue. To bypass the prompt, use the -f or –force flag.
By default, all unused volumes are removed. You can limit the scope using the –filter flag. For
instance, the following command only removes volumes which are not labelled with the keep
label:
ref: https://docs.docker.com/engine/reference/commandline/volume_ls/
$ docker volume prune –filter “label!=keep”
for more options https://docs.docker.com/engine/reference/commandline/volume_prune/
Prune networks
Docker networks don’t take up much disk space, but they do create iptables rules, bridge
network devices, and routing table entries. To clean these things up, you can use docker
network prune to clean up networks which aren’t used by any containers.
$ docker network prune
By default, you are prompted to continue. To bypass the prompt, use the -f or –force flag.
By default, all unused networks are removed. You can limit the scope using the –filter flag. For
instance, the following command only removes networks older than 24 hours:
$ docker network prune –filter “until=24h”
for more options https://docs.docker.com/engine/reference/commandline/network_prune/
Prune everything
The docker system prune command is a shortcut that prunes images, containers, and networks.
In Docker 17.06.0 and earlier, volumes are also pruned. In Docker 17.06.1 and higher, you must
specify the –volumes flag for docker system prune to prune volumes.
$ docker system prune
$ docker system prune –volumes