A Docker Image is a collection of all the required files for an executable. Docker Images are layered, i.e. are stacked on top of each other, with the base image having no parent images.
Docker images can be downloaded from registires, Docker Hub being an example, built from
Dockerfiles or from existing containers.
Given a Dockerfile:
FROM ubuntu CMD echo HelloWorld
an image can be built by:
docker build -t ubuntu-helloworld .
docker pull ubuntu
A container can be commited using the
commit command in a desired state to be stored as an image.
docker run -it --rm ubuntu # Run the following inside the container apt-get update apt-get install -y wget # Stop the container by exiting exit docker commit container-id koraytugay/ubuntu_wget # At this point you should have a new image you can start anytime you like # that comes with wget docker run -it --rm koraytugay/ubuntu
# Pulling an image docker pull repository-name:tag # Examples docker image pull mongo:3.3.11 docker pull hello-world # equivalent to :latest # Listing images docker image ls # Removing an image docker image rm image-id