To get some quick, minimal-effort intuition regarding how images are composed, we will introduce ourselves to various advanced and potentially unfamiliar Docker concepts using Dive. The basic process flow used will be as follows. In this article, we will show how it's possible to reconstruct a Dockerfile from an image using two tools, Dedockify, a customized Python script provided for this article, and dive. In this article, we will explore exactly how to do that by looking inside a Docker image so that we can very closely reconstruct the Dockerfile that built it. Often, you can retrieve most of the information you need to reconstruct a Dockerfile. Whatever the reason, if you wish to recover a Dockerfile from an image, there are options. Or perhaps a compiler for another distribution has an exclusive feature that makes it better optimized to produce binaries during compile time, and you have an uncontrollable compulsion to release a similar image that's just a little more optimized.

Perhaps one of your favorite images is no longer being maintained, and you would like to update it so that it runs on the latest version of Ubuntu. Maybe security vulnerabilities aren't your concern. Even if the Dockerfile was made available, we don't have many assurances that the published image is safe to use. When a Docker image is made publicly available, the Dockerfile is sometimes also provided, either directly in the listing, in a git repository, or through an associated link, but sometimes this is not the case.

It often comes down to the convivence outweighing the perceived risk. This article explores how we can reverse engineer Docker images by examining the internals of how Docker images store data, how to use tools to examine the different aspects of the image, and how we can create tools like Dedockify to leverage the Python Docker API to create Dockerfiles from source images.Īs public Docker registries like Docker Hub and TreeScale increase in popularity, except for the most restrictive environments, it has become common for admins and developers to casually download an image built by an unknown entity.

Docker nav extract software