Docker as a Build/Test Host

Some development teams use Docker containers not as a host for their application in production, but rather as an on-demand, isolated environment for compiling and testing. A developer can easily spin up a build inside a container, specify what tests to run, and run them in a container instead of on their local box. One reason this is handy is if a developer needs to install and validate different dependencies like shared libraries or prerelease software that you might not want to install on your local box. After the build compiles and unit tests pass, the container is then discarded. A more common use case for build and test validation with Docker is not on the local machine, but rather as part of a continuous integration workflow, which we’ll discuss in Chapter 6, “DevOps and Continuous Delivery.”