Why does Docker need a base image?

4 Answers. In fact, Docker works through application of layers that are added to the base image. As you have to maintain coherence between all these layers, you cannot base your first image on a moving target (i.e. your writable file-system). So, you need a read-only image that will stay forever the same.

Which Docker base image should I use?

Use a minimal base image, such as the BusyBox image. This will give you the absolute minimum you need to get a container running. Use the CentOS base image, in which case your container will be running the same or very similar OS.

How Docker Base images are created?

Docker images are created from a Dockerfile that defines a base image and a series of instructions that add your own filesystem layers. What happens if you want to make your own “base image” though? Here’s how to start from scratch and create a complete container filesystem from the ground up.

Where are Docker base images stored?

/var/lib/docker/overlay2
If you use the default storage driver overlay2, then your Docker images are stored in /var/lib/docker/overlay2 . There, you can find different files that represent read-only layers of a Docker image and a layer on top of it that contains your changes.

Does Docker base image contain OS?

Every image contains an complete os. Special docker made OS’s come with a few mega bytes: for example linux Alpine which is an OS with 8 megabytes! But bigger OS like ubuntu/windows can be a few gigabytes.

What is Linux base image?

So the Linux kernel image is an image (a picture of the state) of the Linux kernel that is able to run by itself after giving the control to it. Nowadays, the bootloader loads such an image from the hard disk’s filesystem (driver is needed), replaces itself with it and so gives the control to it.

What is a base image?

A base image is the image that is used to create all of your container images. Your base image can be an official Docker image, such as Centos, or you can modify an official Docker image to suit your needs, or you can create your own base image from scratch.

Can a Docker container be created without a base OS image?

No its not like that. To create any docker image using DockerFile, You need to start with a base docker image. That base docker image can be anything, Like an empty image as well, In the docker file in your example the FROM section says ubuntu, it means its assuming ubuntu as the base image.