Creating images with a Dockerfile

If you’re ever tasked with building a new Docker image, or modifying an existing one – perhaps for a web application that you’re developing – you’ll be making heavy use of Dockerfiles (see the official Dockerfile documentation at https://docs.docker.com/engine/reference/builder/).

A large percentage of new software will already have an official (or at least open-source, third-party) Dockerfile available. Even if you need to do some customizing before you use these, a good place to look for examples is the documentation for the software or framework you use. These examples don’t tend to break as easily as your own custom Dockerfile when major upgrades are released for the packaged software.

Also, some frameworks or development environments, for example, Spring Boot (Java), can generate Docker images as part of the build process.

So, even though there’s a chance you’ll never have to...