Stuck on Docker packaging? Get up to speed quickly

You need to create Docker images for your Python application—but Docker is complex, you don’t quite understand how it works, and you keep getting stuck:

  • Your docker build just failed—now what?
  • How do you debug a docker: Error response from daemon: OCI runtime create failed: container_linux.go:346: starting container process caused "exec: \"flask\": executable file not found in $PATH": unknown.?
  • Why are you wasting time re-running pip install, downloading and re-installing every single package, every single time?
  • Why are you getting a connection reset error when you try to point your browser at your Dockerized application?

You’ve read an introductory tutorial or two, you’ve parsed terse StackOverflow answers, you’ve tried random Google results—but you still don’t have a good mental model of how Docker packaging really works.

Reverse-engineering a complex system like Docker on your own will take you days of research and synthesis. And you’re already busy with the rest of your job; you don’t have time to spare to learn tools the slow way.

The faster way to learn: focus on the fundamentals

Once you understand how Docker packaging works, you’ll have a new and powerful tool at your disposal. The faster you gain this understanding, the more you’ll be able to get done.

So how do you learn effectively and quickly?

Docker is a tool, a means to an end. You need to use it at your job, not write a thesis about it. So you don’t have to memorize every single command, or every single option; that’s what the documentation and online help are for.

But what you do need to understand are the basic abstractions and mechanisms that make it go. Whether it’s debugging a failed build or applying a new Dockerfile command, if you have a good mental model you’ll be able to get your job done.

Just enough to get you up and running quickly

To help you build that intuitive mental model, and get up to speed quickly, I’ve written a concise, developer-focused book: Just Enough Docker Packaging.

This book will show you how Docker packaging actually works, with shell transcripts, plenty of examples, conceptual diagrams, and exercises to help you practice what you’ve learned. Occasionally I’ll even make a mistake, so you can see how I recover.

What readers are saying:

The debugging section was super useful, in its entirety. Besides that, the overall or high-level concepts and how you presented them visually really helped.

I have been using Docker for 2 years maybe, as a developer, and I understood the mechanics, but I did not have time to really think about the details or understand how the images where composed.

The book was really useful to me. I am grateful to you for putting this together.

—Pablo Oliva

As you read the book, you’ll learn just enough about Docker packaging to get up and running quickly, including:

  • The Dockerfile format.
  • The image format.
  • The semantics of naming and tagging images.
  • The image cache.
  • The Docker build process that ties these all together.

And since that’s a lot to cover, and you want to get going as quickly as possible, the book won’t teach you every little detail. Which means you can get through it in an afternoon at work, and then refer back to it as needed.

Just Enough Docker Packaging assumes:

  1. You’re running on a Mac or Linux.
  2. You have some familiarity with command-line tools and the Unix shell.
  3. You have a minimal understanding of Python packaging.
  4. Minimal to zero previous knowledge of Docker.

Ready to learn Docker packaging, quickly and effectively?

What readers are saying:

“Thank you. Your book really helped. I’ve been working with Docker for a few years now and I found the debugging techniques - especially copying files in and out of the container - to be really interesting and immediately useful. I didn’t know these capabilities existed.

I would definitely recommend the book to a colleague if they were trying to get started with Docker or improve their knowledge.

—Alexander Kammerer, Investment Engineer

Just Enough Docker Packaging Production best practices bundle
  • Concise, focused PDF book, last updated in April 2020.
  • Exercises to solidify your understanding.
  • All updates to the 1st edition.
  • 100% money-back guarantee.
  • Everything in the book.
  • Plus, the ~40 page Python on Docker Production Checklist.
  • 35 different best practices for packaging Python applications for production, from security to reproducibility to build time.
  • Extensive examples and additional references.
  • All updates to the 1st edition.
  • 100% money-back guarantee.

Want to buy the book for your whole team? Buy a 10-person license for US$199.

Note: I prefer not to take money from teams working on projects for the military, prisons, fossil fuel extraction, surveillance, national security, or the like. If that applies to you, please don’t purchase this product.

What’s in the book

Chapter by chapter, Just Enough Docker Packaging covers:

  1. Images and containers: what they are and how to use them.
  2. Minimal packaging: your first Docker image for a simple Python application, and the basics of Dockerfile commands.
  3. Docker networking and its impact on packaging: configuring servers, and finding addresses as client software via environment variables and well-known hostnames.
  4. Configuring your application for Docker packaging: persistent data, logging, volumes, command-line parsing.
  5. Sharing images: pulling and pushing, image registries, and understanding image naming.
  6. Smaller and faster builds: build caching, image as layers, skipping files with .dockerignore.
  7. Debugging your build: how to debug failed builds, and containers that won’t start.
  8. Next steps: what to learn next.

The best way to learn from this book is to type along as you read it, running the same commands on your computer. Additionally, Chapters 2 to 7 each have a corresponding exercise to help you practice what you’ve learned.

Changelog

April 2020

  • Expanded the debugging chapter with a new section on extracting files from a failed build.
  • Clarified that --bind 0.0.0.0 and the port number used in portforwarding are specific to the server used, rather than Docker features.
  • Other small improvements.

January 2020

The original release of the book.

Ready to learn Docker packaging, quickly and effectively?

Just Enough Docker Packaging Production best practices bundle
  • Concise, focused PDF book, last updated in April 2020.
  • Exercises to solidify your understanding.
  • All updates to the 1st edition.
  • 100% money-back guarantee.
  • Everything in the book.
  • Plus, the ~40 page Python on Docker Production Checklist.
  • 35 different best practices for packaging Python applications for production, from security to reproducibility to build time.
  • Extensive examples and additional references.
  • All updates to the 1st edition.
  • 100% money-back guarantee.

Want to buy the book for your whole team? Buy a 10-person license for US$199.

Note: I prefer not to take money from teams working on projects for the military, prisons, fossil fuel extraction, surveillance, national security, or the like. If that applies to you, please don’t purchase this product.

About me

Hi, I’m Itamar Turner-Trauring.

I’ve been writing Python since 1999, and I first started using Docker in 2014, when I was part of a team that wrote one of the first distributed storage backends for Docker.

I’ve since built Telepresence, a remote development tool for Kubernetes that was adopted as a Cloud Native Computing Foundation sandbox project and has more than 2000 stars on GitHub. I’ve also deployed a number of production Python applications as Docker images.

Over the past year I’ve been researching Docker packaging for Python in production, resulting in a free guide elsewhere on this site, live training classes, a template implementing best practices, and of course this introductory book.