Book Image

Learn Docker - Fundamentals of Docker 19.x - Second Edition

By : Dr. Gabriel N. Schenker
Book Image

Learn Docker - Fundamentals of Docker 19.x - Second Edition

By: Dr. Gabriel N. Schenker

Overview of this book

Containers enable you to package an application with all the components it needs, such as libraries and other dependencies, and ship it as one package. Docker containers have revolutionized the software supply chain in both small and large enterprises. Starting with an introduction to Docker fundamentals and setting up an environment to work with it, you’ll delve into concepts such as Docker containers, Docker images, and Docker Compose. As you progress, the book will help you explore deployment, orchestration, networking, and security. Finally, you’ll get to grips with Docker functionalities on public clouds such as Amazon Web Services (AWS), Azure, and Google Cloud Platform (GCP), and learn about Docker Enterprise Edition features. Additionally, you’ll also discover the benefits of increased security with the use of containers. By the end of this Docker book, you’ll be able to build, ship, and run a containerized, highly distributed application on Docker Swarm or Kubernetes, running on-premises or in the cloud.
Table of Contents (25 chapters)
1
Section 1: Motivation and Getting Started
4
Section 2: Containerization, from Beginner to Black Belt
11
Section 3: Orchestration Fundamentals and Docker Swarm
18
Section 4: Docker, Kubernetes, and the Cloud

Using Docker Compose overrides

Sometimes, we want to run our applications in different environments that need specific configuration settings. Docker Compose provides a handy capability to address exactly this issue.

Let's make a specific sample. We can define a base Docker Compose file and then define environment-specific overrides. Let's assume we have a file called docker-compose.base.yml with the following content:

version: "2.4"
services:
web:
image: fundamentalsofdocker/ch11-web:2.0
db:
image: fundamentalsofdocker/ch11-db:2.0
volumes:
- pets-data:/var/lib/postgresql/data

volumes:
pets-data:

This only defines the part that should be the same in all environments. All specific settings have been taken out.

Let's assume for a moment that we want to run our sample application on a CI system, but there we want to use different settings for...