Book Image

Learn Docker - Fundamentals of Docker 18.x

By : Dr. Gabriel N. Schenker
Book Image

Learn Docker - Fundamentals of Docker 18.x

By: Dr. Gabriel N. Schenker

Overview of this book

Docker containers have revolutionized the software supply chain in small and big enterprises. Never before has a new technology so rapidly penetrated the top 500 enterprises worldwide. Companies that embrace containers and containerize their traditional mission-critical applications have reported savings of at least 50% in total maintenance cost and a reduction of 90% (or more) of the time required to deploy new versions of those applications. Furthermore they are benefitting from increased security just by using containers as opposed to running applications outside containers. This book starts from scratch, introducing you to Docker fundamentals and setting up an environment to work with it. Then we delve into concepts such as Docker containers, Docker images, Docker Compose, and so on. We will also cover the concepts of deployment, orchestration, networking, and security. Furthermore, we explain Docker functionalities on public clouds such as AWS. By the end of this book, you will have hands-on experience working with Docker containers and orchestrators such as SwarmKit and Kubernetes.
Table of Contents (21 chapters)
Title Page
Packt Upsell
Contributors
Preface
Index

Using host volumes


In certain scenarios, such as when developing new containerized applications or when a containerized application needs to consume data from a certain folder produced, say, by a legacy application, it is very useful to use volumes that mount a specific host folder. Let's look at the following example:

$ docker container run --rm -it \
    -v $(pwd)/src:/app/src \
    alpine:latest /bin/sh

The preceding expression interactively starts an alpine container with a shell and mounts the subfolder src of the current directory into the container at /app/src. We need to use $(pwd) (or 'pwd' for that matter) which is the current directory, as when working with volumes we always need to use absolute paths.

Developers use these techniques all the time when they are working on their application that runs in a container, and want to make sure that the container always contains the latest changes they make to the code, without the need to rebuild the image and rerun the container after each...