Chapter 3. Software installation simplified
This chapter covers
- Identifying software
- Finding and installing software with Docker Hub
- Installing software from alternative sources
- Understanding filesystem isolation
- Working with images and layers
Chapters 1 and 2 introduced new concepts and abstractions provided by Docker. This chapter dives deeper into container filesystems and software installation. It breaks software installation into three steps, as illustrated in figure 3.1.
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The first step in installing any software is identifying the software you want to install. You know that software is distributed using images, but you need to know how to tell Docker exactly which image you want to install. We’ve already mentioned that repositories hold images, but this chapter shows how repositories and tags are used to identify images in order to install the software you want.
This chapter details the three main ways to install Docker images:
- Using Docker registries
- Using image files with docker save and docker load
- Building images with Dockerfiles
In the course of reading this material, you’ll learn how Docker isolates installed software and you’ll be exposed to a new term, layer. Layers, an important concept when dealing with images, provide multiple important features. This chapter closes with a section about how images work. That knowledge will help you evaluate image quality and establish a baseline skillset for part 2 of this book.