Docker

Docker is used to create containers. In a container system resources are separated from each other e.g. to create a development environment where the developer can experiment freely without the risk of jeopardizing the host system.

A dockerfile defines what will be in the docker image, running the image will create a container.

Installation

apt install docker.io
apt install docker-buildx

This creates a working container with a python virtual environment

Dockerfile in /etc/docker

FROM debian
LABEL name="Hans de Ridder"
RUN apt-get update
RUN apt-get -y install python3-full
RUN python3 -m venv /home/ubuntu/venv
ENV PATH="/home/ubuntu/venv/bin:$PATH"
RUN pip install pandas
CMD ["echo", "I'm alive"]

docker build -t <name>

<tag> /etc/docker

This builds the image with a name and a tag

docker image ls

List all existing images

docker run -v <hostdir>:<containerdir> -it <image ID> bash

Create the container and open a bash prompt in it. When leaving the shell the container is closed

This way you can run any command in a container that only exists while the command is running.

<hostdir> is mounted on <containerdir> which will be created automatically

docker ps -a

List all containers

docker system prune

Delete unused images and build caches

docker prune -a

Delete unused images and all build cache