Getting stuck on Docker packaging? Learn the debugging techiques you’ll need

There are many technologies you need to learn as a Python programmer, and Docker is just one more item on an ever-expanding list. So when you’ve used it before, you’ve copy/pasted enough docker run and docker-compose commands to get things going, and then moved on.

But now you need to start packaging your application, which means doing everything from writing Dockerfiles to debugging broken builds—and your basic knowledge isn’t enough.

  • 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 need to actually understand how Docker packaging works, and quickly; you’ve still got plenty of other work to do. All those bugs in the issue tracker won’t fix themselves, and the features won’t be shipping if you can’t get back to writing more Python.

Become more productive–fast

Right now Docker is a stumbling block. But for those who understand how it works, Docker is a useful enough tool that it’s become ubiquitous.

That means applying Docker packaging will help you become more productive now, and it’s a skill that will make you more employable in the future. And since it’s going to make you more effective at your job, wouldn’t it be great to learn it on the job, and quickly?

Learn Docker packaging in an afternoon

To help you learn the fundamentals of Docker packaging, I’ve written a concise, practical, book specifically for Python developers: Just Enough Docker Packaging. The book is:

  • Created for learning: It’s based on the training materials I use to teach live classes.
  • For Python developers: All the examples use Python.
  • Short and focused: You’ll learn how Docker packaging works so you can package your application, and how to debug your build when things go wrong. You should be able to read the whole book in one afternoon.

The 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 were composed.

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

—Pablo Oliva

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


Option #1: Production best practices bundle ($95)

Includes Just Enough Docker Packaging:

  • Learn the basics of Docker packaging.
  • Concise, focused PDF book, last updated in April 2020.
  • Exercises to solidify your understanding.
  • All updates to the 1st edition, delivered by email.
  • 100% money-back guarantee.

Plus, take the next step and learn how to package for production by adding on the Python on Docker Production Quickstart:

  • Focuses specifically on Python running in production.
    You’re not writing Go, you’re writing Python–and that makes a big difference.
  • Covers over 60 best practices.
    This includes 25 best practices you won’t find in the free content elsewhere on this site.
  • Provides a step-by-step iterative implementation plan.
    Given that many best practices, it’s easy to get overwhelmed. So instead of trying to figure out where to start on your own, you can follow the included plan.
  • Won’t waste your time.
    It’s a concise summary, ~80 pages of to-the-point information, with examples and references to additional information.
  • All updates to the 1st edition, delivered by email.
  • 100% money-back guarantee.
Buy the book+quickstart for US$95

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


Option #2: Just the book ($29)

Includes Just Enough Docker Packaging:

  • Learn the basics of Docker packaging.
  • Concise, focused PDF book, last updated in April 2020.
  • Exercises to solidify your understanding.
  • All updates to the 1st edition.
  • 100% money-back guarantee.
Buy the book for US$29

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


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?


Option #1: Production best practices bundle ($95)

Includes Just Enough Docker Packaging:

  • Learn the basics of Docker packaging.
  • Concise, focused PDF book, last updated in April 2020.
  • Exercises to solidify your understanding.
  • All updates to the 1st edition, delivered by email.
  • 100% money-back guarantee.

Plus, take the next step and learn how to package for production by adding on the Python on Docker Production Quickstart:

  • Focuses specifically on Python running in production.
    You’re not writing Go, you’re writing Python–and that makes a big difference.
  • Covers over 60 best practices.
    This includes 25 best practices you won’t find in the free content elsewhere on this site.
  • Provides a step-by-step iterative implementation plan.
    Given that many best practices, it’s easy to get overwhelmed. So instead of trying to figure out where to start on your own, you can follow the included plan.
  • Won’t waste your time.
    It’s a concise summary, ~80 pages of to-the-point information, with examples and references to additional information.
  • All updates to the 1st edition, delivered by email.
  • 100% money-back guarantee.
Buy the book+quickstart for US$95

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


Option #2: Just the book ($29)

Includes Just Enough Docker Packaging:

  • Learn the basics of Docker packaging.
  • Concise, focused PDF book, last updated in April 2020.
  • Exercises to solidify your understanding.
  • All updates to the 1st edition.
  • 100% money-back guarantee.
Buy the book for US$29

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


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.