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Table Of Contents

Learning Docker - Second Edition

By : Pethuru Raj, Vinod Singh, Jeeva S. Chelladhurai

3 (5)

Buy this Book

Learning Docker

3 (5)

By: Pethuru Raj, Vinod Singh, Jeeva S. Chelladhurai

Buy this Book

Overview of this book

Docker is an open source containerization engine that offers a simple and faster way for developing and running software. Docker containers wrap software in a complete filesystem that contains everything it needs to run, enabling any application to be run anywhere – this flexibily and portabily means that you can run apps in the cloud, on virtual machines, or on dedicated servers. This book will give you a tour of the new features of Docker and help you get started with Docker by building and deploying a simple application. It will walk you through the commands required to manage Docker images and containers. You’ll be shown how to download new images, run containers, list the containers running on the Docker host, and kill them. You’ll learn how to leverage Docker’s volumes feature to share data between the Docker host and its containers – this data management feature is also useful for persistent data. This book also covers how to orchestrate containers using Docker compose, debug containers, and secure containers using the AppArmor and SELinux security modules.

Preface

What this book covers

What you need for this book

Who this book is for

Conventions

Reader feedback

Customer support

Free Chapter

Getting Started with Docker

The key drivers for Dockerization

Differentiating between containerization and virtualization

Installing the Docker Engine

Understanding the Docker setup

Downloading the first Docker image

Running the first Docker container

Summary

Handling Docker Containers

Clarifying Docker terms

Working with Docker images

Working with an interactive container

Summary

Building Images

Docker's integrated image building system

A quick overview of the Dockerfile's syntax

The Dockerfile build instructions

A brief on the Docker image management

Best practices for writing a Dockerfile

Summary

Publishing Images

Understanding Docker Hub

Pushing images to Docker Hub

Automating the build process for images

Private repositories on Docker Hub

Organizations and teams on Docker Hub

The REST API for Docker Hub

Summary

Running Your Private Docker Infrastructure

Docker Registry

Docker Registry use cases

Running Docker Registry and pushing the image

Running the Docker Registry on localhost with an SSL certificate

Running Docker Registry with restrictions

Managing Docker Registry with Docker Compose

Load balancing consideration

Webhook notifications

Docker Registry HTTP API support

Summary

Running Services in a Container

A brief overview of container networking

Envisaging container as a service

Exposing container services

Summary

Sharing Data with Containers

Data volume

The volume management command

Sharing host data

Sharing data between containers

Avoiding common pitfalls

Summary

Orchestrating Containers

Docker inbuilt service discovery

Linking containers

Orchestration of containers

Summary

Testing with Docker

A brief overview of TDD

Testing your code inside Docker

Integrating Docker testing into Jenkins

Summary

Debugging Containers

Process-level isolation for Docker containers

The docker exec command

The docker ps command

The docker top command

The docker stats command

The Docker events command

The docker logs command

The docker attach command

Debugging a Dockerfile

Summary

Securing Docker Containers

The security scenario in the containerization domain

Immutable infrastructure

The best practices for container security

Summary

The Docker Platform – Distinct Capabilities and Use Cases

Describing containers

Briefing the Docker platform

Implications of the Docker technology

The Docker use cases

Summary

Running the first Docker container

Now you can start your first Docker container as shown here:

Cool, isn't it? You have set up your first Docker container in no time. In the preceding example, the docker run subcommand has been used to create a container from the hello-world image.

Troubleshooting Docker containers

Most of the times you will not encounter any issues when installing Docker. However, unexpected failures might occur. Therefore, it is necessary to discuss the prominent troubleshooting techniques and tips. Let's begin by discussing troubleshooting know-how in this section. The first tip is that Docker's running status should be checked using the following command:

$ sudo service docker status

If the Docker service is up-and-running, the Active column (the third from the top) will list the status of the Docker service as active (running), as shown next:

However, if the Active column shows inactive or maintenance as the status, your Docker service is not running. In such cases, restart the Docker service, as shown here:

$ sudo service docker restart

If you are still experiencing issues with the Docker setup, then you must extract the Docker log, using the journalctl -u docker command, for further investigation.