Removing Docker Images, Containers, and Volumes with Ease
Docker makes it easy to wrap your
applications and services in containers so you can run them anywhere. As you
work with Docker, however, it’s also easy to accumulate an excessive number of
unused images, containers, and data volumes that clutter the output and consume
disk space.
Docker doesn’t provide direct
cleanup commands, but it does give you all the tools you need to clean up your
system from the command line. This cheat sheet-style guide provides a quick
reference to commands that are useful for freeing disk space and keeping your
system organized by removing unused Docker images, containers, and volumes.
Using the Cheat Sheet
This guide is in cheat sheet format
with self-contained command-line snippets.
Jump to any section that is
relevant to the task you are trying to complete.
The command substitution syntax:
$ command $(command)
This is available in many popular
shells such as bash, zsh, and Windows PowerShell.
Removing Docker Images
Use the Docker images command with
the -a flag to locate the ID of the images you want to remove. This will show
you every image, including intermediate image layers. When you’ve located the
images you want to delete, you can pass their ID or tag to Docker rmi:
List:
$ docker images -a
Remove:
$ docker rmi image
Remove Dangling Images
Docker images consist of multiple
layers. Dangling images are layers that have no relationship to any tagged
images. They no longer serve a purpose and consume disk space. They can be
located by adding the filter flag, -f with a value of dangling=true to the Docker
images command. When you’re sure you want to delete them, you can add the -q
flag, then pass their ID to Docker rmi:
Note: If you build an image without
tagging it, the image will appear on the list of dangling images because it has
no association with a tagged image. You can avoid this situation by providing a
tag when you build, and you can retroactively tag an images with the Docker tag
command.
List:
$ docker images -f dangling=true
Remove:
$ docker rmi $(docker images -f
dangling=true -q)
Removing Images According to a
Pattern
You can find all the images that
match a pattern using a combination of Docker images and grep. Once you’re
satisfied, you can delete them by using awk to pass the IDs to Docker rmi. Note
that these utilities are not supplied by Docker and are not necessarily
available on all systems:
List:
$ docker ps -a | grep
"pattern"
Remove:
$ docker images | grep
"pattern" | awk '{print $1}' | xargs docker rm
Remove all Images
All the Docker images on a system
can be listed by adding -a to the Docker images command. Once you’re sure you
want to delete them all, you can add the -q flag to pass the Image ID to Docker
rmi:
List:
$ docker images -a
Remove:
$ docker rmi $(docker images -a -q)
Removing Docker Containers
Use the Docker ps command with the
-a flag to locate the name or ID of the containers you want to remove:
List:
$ docker ps -a
Remove:
$ docker rm ID_or_Name
Remove a Container Upon Exit
If you know when you’re creating a
container that you won’t want to keep it around once you’re done, you can run
Docker run — rm to automatically delete it when it exits.
Run and Remove:
$ docker run -rm image_name
Remove all Exited Containers
You can locate containers using
Docker ps -a and filter them by their status: created, restarting, running,
paused, or exited. To review the list of exited containers, use the -f flag to
filter based on status. When you’ve verified you want to remove those containers,
using -q to pass the IDs to the Docker rm command.
List:
$ docker ps -a -f status=exited
Remove:
$ docker rm $(docker ps -a -f
status=exited -q)
Remove Containers Using More Than
One Filter
Docker filters can be combined by
repeating the filter flag with an additional value. This results in a list of
containers that meet either condition. For example, if you want to delete all
containers marked as either Created (a state which can result when you run a
container with an invalid command) or Exited, you can use two filters:
List:
$ docker ps -a -f status=exited -f
status=created
Remove:
$ docker rm $(docker ps -a -f
status=exited -f status=created -q)
Remove Containers According to a
Pattern
You can find all the containers
that match a pattern using a combination of Docker ps and grep. When you’re
satisfied that you have the list you want to delete, you can use awk and xargs
to supply the ID to Docker rmi. Note that these utilities are not supplied by
Docker and not necessarily available on all systems:
List:
$ docker ps -a | grep
"pattern”
Remove:
$ docker ps -a | grep
"pattern" | awk '{print $3}' | xargs docker rmi
Stop and Remove all Containers
You can review the containers on
your system with Docker ps. Adding the -a flag will show all containers. When
you’re sure you want to delete them, you can add the -q flag to supply the IDs
to the Docker stop and Docker rm commands:
List:
$ docker ps -a
Remove:
$ docker stop $(docker ps -a -q)
$ docker rm $(docker ps -a -q)
Removing Docker Volumes
Use the Docker volume ls command to
locate the volume name or names you wish to delete. Then you can remove one or
more volumes with the Docker volume rm command:
List:
$ docker volume ls
Remove:
$ docker volume rm volume_name
Remove Dangling Volumes
Since the point of volumes is to
exist independent from containers, when a container is removed, a volume is not
automatically removed at the same time. When a volume exists, and is no longer
connected to any containers, however, it’s called a dangling volume. To locate
them to confirm you want to remove them, you can use the Docker volume ls
command with a filter to limit the results to dangling volumes. When you’re
satisfied with the list, you can add a -q flag to provide the volume name to
Docker volume rm:
List:
$ docker volume ls -f dangling=true
Remove:
$ docker volume rm $(docker volume
ls -f dangling=true -q)
Remove a Container and its Volume
If you created an unnamed volume,
it can be deleted at the same time as the container using the -v flag. Note
that this only works with unnamed volumes. When the container is successfully
removed, its ID is displayed. Note that no reference is made to the removal of
the volume. If it is unnamed, it is silently removed from the system. If it is
named, it silently stays present.
Remove:
$ docker rm -v container_name
Conclusion
This guide covers some of the
common commands used to remove images, containers, and volumes. There are many
other combinations and flags that can be used with each. For a comprehensive
guide to what’s available, see the Docker documentation for Docker rmi, Docker
rm and Docker volume rm.[Source]-https://medium.com/@jon.froiland/removing-docker-images-containers-and-volumes-with-ease-fdf16bebccec
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