How to Remove Docker Containers

Docker is a platform that provides a set of PaaS (Platform as a Service) products that help developers containerize applications, allowing them to run consistently across various supported environments. The core component of Docker is Docker Engine which consists of:

• Docker Daemon: The process responsible for building, running, and managing containerized applications.
• Docker Client: A command-line interface (CLI) used to interact with the Docker Daemon

A Docker container is a self-contained runtime instance of a Docker image. It includes the application and all its dependencies, enabling developers to package software and its dependencies into one unit and deploy it across different environments.

Containers, once created, can take up system resources, and it’s good practice to remove unused or stopped containers to free up those resources.

Accessing a list of all existing containers

The list of all existing containers and their container IDs can be accessed using the command `docker ps -a`

docker ps -a

Removing a specific container

A specific container (which is not running) can be removed using its container id and the following command `docker rm <container_id_or_name>`

docker rm <container_id_or_name>

To remove a specific container that is currently running stop the container using `docker stop <container_id_or_name>` and then remove it.

Removing multiple containers

You can also remove multiple containers as follows:

docker rm <container_id_or_name_1> <container_id_or_name_2>

Forcibly removing running containers

To remove a container that is still running or to forcibly remove a container the -f flag can be used as follows:

docker rm -f <container_id_or_name>

Removing all unused containers

you can remove all the unused containers to free up system resources by using the following command:

docker container prune

What happens if I remove a running container without the -f flag?

The -f flag forcefully stops and removes the container. If you try to remove a running container without using the -f flag, Docker will return an error.

How can I avoid running out of system resources due to unused data in your Docker environment?

To avoid running out of system resources due to unused containers, images, caches etc you can use the following command which removes all unused data in your docker environment

docker system prune

What happens to the Docker image when I remove a container?

When you remove a Docker container, the underlying Docker image remains intact. Removing a container only deletes the container’s runtime instance, not the image it was created from.