A screenshot from https://c14r.io/ — A tool that let’s you visualize container hierarchies

Introducing c14r.io: A tool that helps you to understand Container Image Hierarchy

I love Kubernetes and Containerization! Used wisely, it enables you to be your own One Developer/Operator Army. Understanding how a particular container image came into being is not always easy. As thematized in this “relevant XKCD”:

https://xkcd.com/1988/ — Containers

Containers are often used without entirely understanding how they are composed internally. Inexperienced developers often trust an image tag for instance called centos or ubuntu. From a security perspective, this is a challenge, as a container does not provide the same level of isolation as for instance a VM.

It starts with the question: What base image is this image using? When was this image built? Who else uses this base image?

Getting an answer to these questions usually means digging through Dockerfiles, inspecting image layers, comparing various past image pushes.

I find myself often executing such activities when working with container technology. That’s why I decided to build c14r, a container browser that lets you visualize image hierarchies:

You start by typing an image you would like to analyze. A good demo example is debian:bullseye. To open all the nodes you can click on “expand all”. For further information about an image, you can click on it. c14r will show you all pushes done using that tag and the corresponding instructions.

You can try it yourself now on: https://c14r.io/

Disclaimer: c14r is in MVP-state. It still has some bugs and missing features (e.g. images with multiple architectures are not well reflected yet and support for the Microsoft Container Registry or Quay is currently missing)



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