Chapter 1, What Are Containers and Why Should I Use Them?, introduces the concept of containers and why they are so extremely useful in the software industry.
Chapter 2, Setting Up a Working Environment, discusses in detail how to set up an ideal environment for developers, DevOps, and operators that can be used when working with Docker containers.
Chapter 3, Mastering Containers, explains how to start, stop, and remove containers. We will also see how to inspect containers to retrieve additional metadata from them. Furthermore, we'll see how to run additional processes, how to attach to the main process in an already running container, and how to retrieve logging information from a container that is produced by the processes running inside it. Finally, the chapter introduces the inner workings of a container, including such things as Linux namespaces and groups.
Chapter 4, Creating and Managing Container Images, presents the different ways to create the container images that serve as the templates for containers. It introduces the inner structure of an image and how it is built. This chapter also explains how to lift and shift an existing legacy application so that it can run in containers.
Chapter 5, Data Volumes and Configuration, introduces data volumes, which can be used by stateful components running in containers. The chapter also shows how we can define individual environment variables for the application running inside the container, as well as how to use files containing whole sets of configuration settings.
Chapter 6, Debugging Code Running in Containers, discusses techniques commonly used to allow a developer to evolve, modify, debug, and test their code while running in a container. With these techniques at hand, the developer will enjoy a frictionless development process for applications running in a container, similar to what they experience when developing applications that run natively.
Chapter 7, Using Docker to Supercharge Automation, shows how we can use tools to perform administrative tasks without having to install those tools on the host computer. We will also see how to use containers that host and run test scripts or code used to test and validate application services running in containers. Finally, this chapter guides us through the task of building a simple Docker-based CI/CD pipeline.
Chapter 8, Advanced Docker Usage Scenarios, presents advanced tips, tricks, and concepts that are useful when containerizing complex distributed applications, or when using Docker to automate sophisticated tasks.
Chapter 9, Distributed Application Architecture, introduces the concept of a distributed application architecture and discusses the various patterns and best practices that are required to run a distributed application successfully. Finally, it discusses the additional requirements that need to be fulfilled to run such an application in production.
Chapter 10, Single-Host Networking, presents the Docker container networking model and its single-host implementation in the form of the bridge network. This chapter introduces the concept of software-defined networks and explains how they are used to secure containerized applications. It also discusses how container ports can be opened to the public and thus make containerized components accessible from the outside world. Finally, it introduces Traefik, a reverse proxy, to enable sophisticated HTTP application-level routing between containers.
Chapter 11, Docker Compose, addresses the concept of an application consisting of multiple services, each running in a container, and how Docker Compose allows us to easily build, run, and scale such an application using a declarative approach.
Chapter 12, Orchestrators, presents the concept of orchestrators. It explains why orchestrators are needed and how they work conceptually. The chapter will also provide an overview of the most popular orchestrators and name a few of their pros and cons.
Chapter 13, Introduction to Docker Swarm, introduces Docker's native orchestrator, SwarmKit. We will see all the concepts and objects SwarmKit uses to deploy and run a distributed, resilient, robust, and highly available application in a cluster on premises or in the cloud. The chapter also introduces how SwarmKit ensures secure applications using software-defined networks to isolate containers and secrets to protect sensitive information. Additionally, this chapter shows how to install a highly available Docker swarm in the cloud. It introduces the routing mesh, which provides Layer 4 routing and load balancing. Finally, it shows how to deploy an application consisting of multiple services onto the swarm.
Chapter 14, Zero-Downtime Deployments and Secrets, explains how to deploy services or applications onto a Docker swarm with zero downtime and automatic rollback capabilities. It also introduces secrets as a means to protect sensitive information.
Chapter 15, Introduction to Kubernetes, introduces the current most popular container orchestrator. It introduces the core Kubernetes objects that are used to define and run a distributed, resilient, robust, and highly available application in a cluster. Finally, it introduces MiniKube as a way to locally deploy a Kubernetes application, and also the integration of Kubernetes with Docker for Mac and Docker for Windows.
Chapter 16, Deploying, Updating, and Securing an Application with Kubernetes, explains how to deploy, update, and scale applications into a Kubernetes cluster. It also explains how to instrument your application services with liveness and readiness probes to support Kubernetes in its health and availability checking. Furthermore, the chapter explains how zero-downtime deployments are achieved to enable disruption-free updates and rollbacks of mission-critical applications. Finally, the chapter introduces Kubernetes secrets as a means to configure services and protect sensitive data.
Chapter 17, Monitoring and Troubleshooting an App Running in Production, teaches different techniques to monitor an individual service or a whole distributed application running on a Kubernetes cluster. It also shows how to troubleshoot an application service that is running in production without altering the cluster or the cluster nodes on which the service is running.
Chapter 18, Running a Containerized App in the Cloud, provides an overview of some of the most popular ways of running containerized applications in the cloud. We include self-hosting and hosted solutions and discuss their pros and cons. Fully managed offerings of vendors such as Microsoft Azure and Google Cloud Engine are briefly discussed.