Containers Under The Hood

A Bottom-up Approach to Docker and Kubernetes

What you'll learn
Ever wondered how Docker or any other container technology works under the hood?
Understand in depth the core concepts that underlie any container technology - Namespaces, Cgroups and Overlay Filesystems.
Understand the different Namespaces that enable Containers with detailed examples on PID, MOUNT, UTS and IPC Namespaces
Gain in-depth knowledge on Overlay Filesystems - what they are and what role they play in the world of Containers
Learn how to use Cgroups with step-by-step concrete examples for controlling the CPU and Memory available to an application
Create your own container by just using Namespaces, Cgroups and Overlay Filesystems
Learn what container images are, how image layering works under the hood, how they related to Overlay FS using detailed hands-on working examples.
See under the hood to understand how Cgroups are used in Containers and Kubernetes for resource allocation.
What a Kubernetes Control Plane is, what the key components are and how they work together
Gain a solid understanding of related concepts such as the proc filesystem and mount points. Learn how these tie into Namespaces.

Requirements
Basic programming skills and a basic understanding of Linux - how to use a text editor and some basic Linux commands. I will walk you through any related concepts needed to understand the core topics in the course.
What you need to bring is a curiosity to understand how container technologies work under the hood.
Patience and willingness to go through the concepts, demos and also get your hands dirty using the Virtual Machine that comes with the course.
If you like to follow along and try out the examples, which is highly recommended, you should be able to set up a VM that comes for free with the course.

Description
This is not a traditional course around Docker or Kubernetes, but instead takes a bottom-up approach. Have you ever wondered how Containers work? No, I don't mean just creating a Dockerfile or a Yaml file. Have you ever asked yourself (or others) what are the key mechanisms that enable us to isolate an application or to control how much CPU or Memory it gets?

How is it possible for an application to run on the same physical machine as other applications, yet not know about them? How do technologies like Docker make it happen? For many of us, Containers and Kubernetes Pods are just a black box. But they don't have to be. In this course, you will learn the foundational mechanisms that make Containers possible - Namespaces, Overlay Filesystems and Cgroups. We will take an in-depth look at each of these concepts and understand how they combine to give us Containers.

Hands-on Course : The concepts will be demonstrated with detailed hands-on examples throughout the course. You will have access to a Ubuntu Virtual Machine that I have used for the demos. The course will include a good mix of theory and demos to illustrate the concepts.

Here is what you will learn in this course

Namespaces: We will start with how Namespaces enable isolation, the key mechanism in containerization. We will take a detailed look at different kinds of Namespaces - PID, MNT, IPC and UTS , with hands-on examples to demonstrate each of these Namespaces.

Overlay Filesystems: Next, we will look at what Overlay Filesystems are, and understand the key role they play in the world of containers. Again, we will see working examples of how to create an Overlay Filesystem and how they enable sharing modules across multiple containers.

Cgroups: We will also take an in-depth look at what Cgroups are, how they enable us to control the amount of resources available to an application. We will create our own Cgroups for controlling the amount of Memory and CPU available to an example application.

Related System Concepts: You will also learn related system concepts such as the Proc filesystem and Mount Points, which will come in handy while understanding the PID and MNT Namespaces.

For the demos, we will use very simple, easy-to-understand examples instead of complex applications. The focus will be on driving home the key concepts in this course.

Docker: Once we have a solid understanding of Namespaces, Overlay Filesystems and Cgroups, we will jump into Docker. We will understand what Docker Images are and how to create one. Then, we will dive deep into how image layering works in Docker, and tie this back to the Overlay Filesystem. There will be detailed working examples to demonstrate how image layering works in Docker and we will peel these images layer-by-layer. Finally, using concrete working examples, we will demonstrate how Cgroups work behind the scenes when we control the amount of CPU or Memory available to a Docker container.

Kubernetes: We will look at the idea of a Pod, why it exists and also create a Pod by just using Namespaces. Then, we will create Kubernetes Pods, and understand other resources such as Replica Sets and Deployments. We will understand what the key components of a Kubernetes Control Plane are and how they come together in helping us orchestrate Pods. Finally, we will demonstrate how Cgroups are again the key mechanism that enable us to control resources available to a Pod, such as CPU and Memory.

This course will keep evolving as I will continue to add more advanced topics.

Why this Course?

Because basics do not change. Once you have a firm grasp of these foundational concepts, you will be well positioned to learn any container technology of choice with ease and a lot more clarity. In addition, these ideas are used in other areas - for example Cgroups are also used in Virtual Machines. The knowledge you gain from this course will broaden your skill-set. With a solid understanding of how things work under the hood, you will see Containers in new light.

What you need to bring to the table?

Curiosity and Patience. Curiosity to understand how containers work under the hood. I intentionally go slow, specifically in the beginning of the course, setting the stage for the problem that Namespaces solve. You must be patient and understand the problem first, so that you can really appreciate why Namespaces exist and how they work. Once you understand the problem and the story setup that we will use for the most part of the course, you will start to truly appreciate the core concepts.

Pre-requisite background: If you have done some level of programming and can use basic command-line Linux, you are good to go. You are not expected to have any kind of background in container technologies such as Docker or Kubernetes. I will walk you through any related areas such as the Proc filesystem and Mount Points. Also, you do not have to have an in-depth knowledge of Linux. I will provide the required background wherever necessary. It would be beneficial if you can download and use the VM that comes for free with this course.

Disclaimer

Docker and the Docker logo are trademarks or registered trademarks of Docker, Inc. in the United States and other countries. Docker, Inc. and other parties may also have trademark rights on other terms used herein. This course is not in any way or form affiliated with, certified, accredited, or endorsed by Docker, Inc.

Kubernetes and the Kubernetes logo are trademarks or registered trademarks of The Linux Foundation in the United States and other countries. The Linux Foundation and other parties may also have trademark rights on other terms used herein. This course is not in any way or form affiliated with, certified, accredited, or endorsed by Kubernetes or The Linux Foundation.

Who this course is for
This course is for anyone who is curious and eager to learn how Containers work under the hood. You are not expected to come in with an understanding of containers. We will start from the very basics.
Whether you are a novice looking to get started with Containers and Kubernetes or have been using them for a while, if you want to understand the key mechanisms that make these technologies work, you will gain a lot from this course.
This course comes with an Ubuntu Virtual Machine that includes all the needed software. This is the same VM I have used in this course. To truly appreciate and digest the core concepts, you must be willing to try out the examples on your own.