Smart guide to managing Docker container

Docker technology is an open-source containerization platform allowing you to rapidly develop, test and deploy applications as portable containers that can run virtually anywhere. Docker containers come with all the libraries to provide a self-sufficient environment needed for software deployment and testing. The developer environment can be very chaotic, leading to old or unused or outdated components in the system. With the following guide, we will show you how to organize a Docker environment by removing the images, containers, and volumes.

• Requirement
• Remove Unused Resources
• Remove Docker Images
• Remove Docker Containers
• Remove Docker Volumes
• Remove Docker Networks
• Conclusion

Requirement

- Ubuntu 18 server running Docker
- Terminal/Command prompt
- Root user account or user with Sudo privileges

Removing All Unused Docker Resources

A lot of files, including unused data, are created in a development environment. This can lead to cluttering the disk space. Docker does not remove any unused data by itself, and hence it is a good practice to remove time and unused and unwanted data.

To remove all images, containers, and networks that are not associated with a container.

This command will remove everything, including dangling images and stopped containers.

Once you press Y and enter, it should give you the list of deleted containers.

Please note, the above command will only remove dangling Docker images. If you would like to include all unused images, execute the following command:

Output

The previous two commands will not touch unused volumes. If you'd like to remove that as well, use the following command:

Important note: Prune command is not reversible and hence must be carefully used.

Removing Docker Images

To view all of your Docker images, you can use:

This will give you a list of all the docker images and their details in the following format.

Output

Using the image id from the output above, you can pass the value to the following command to remove the docker image.

To remove dangling images that are most recent and untagged, we will use the "docker remove all images" command as shown here:

However, to remove Docker images that are present in existent containers that are also tagged, we can use this:

If you wish to remove all images, for example, that may fall under a specific time frame, use the command:

Note: To forcefully execute any "remove" command at any given time, use the -f or –force flag.

Removing Docker Containers

Similarly to before, to see the list of all Docker containers, you will need to run this command:

If you want to remove a specific container, enter the CONTAINER ID as shown in this example:

To remove all the containers that stopped in the application, follow this command:

Take note that this will remove all stopped containers. To view the list of what containers will be deleted using the beforementioned command, use the –filter flag:

To limit the removal of containers that stopped, for example, according to the time frame, you can use the following command:

If you want to remove a container once you're done working with it, you start one by adding a –rm flag. Here's an example of how to remove such a container:

When you're done, the container will be deleted automatically.

Removing Docker Volumes

Volumes are used for multiple containers, and there will likely be a number of either unused or stopped volume files.

These files are not removed automatically, and neither is there a setting in Docker to do so as that can cause significant loss or damage to data.

First, to get all Docker volume IDs, use the following command:

If you want to remove a particular volume, use this command followed by the VOLUME NAME:

To remove all unused volumes using a single command, you can use the following:

If Docker volumes have labels attached to them, you can also use this:

In this example, the command will only remove those volume files which are not labeled and assigned with the "keep" label.

Removing Docker Networks

Though Docker networks don't take much disk space, they can cause problems if unnecessary files are not cleared from the disk. One problem is that it creates rules for iptables and bridge networks with routing table entries, which can cause some issues in the long run.

For a complete list of NETWORK IDs, use the following command:

To remove a specific network, you can use:

If you wish to remove all unsued networks, use the following command:

For a filter based on the time frame, 24 hours in this example, you can enter instead:

Note: If you get an error when trying to remove a specific network, it means that an existing container uses that particular network and will have to be removed before continuing.

Conclusion

Nowadays, Docker is gaining considerable momentum and is used by many famous companies worldwide. It is one of the best platforms to date that allows more convenient development solutions and allows unlimited testing and experimentation to quickly and efficiently create applications.

In this tutorial, you've learned how to clear unused Docker images, containers, volumes, and networks. If you have any more questions, feel free to leave a comment down below.