You can use the -f argument to specify a different file, but it's a good practice to use this default name and have one Dockerfile per directory if you need to build more than one image in a project. By default, Docker will look for a file named Dockerfile with no extension. Think of it as the blueprint or source code. A Dockerfile is a set of instructions for Docker to build an image. Once Docker is installed, you need to create a Dockerfile. The first step is getting Docker, you can get it for Mac, Windows, and all of the popular GNU/Linux distributions. What's a Docker image? What's a Docker container? How do I run it? This post tries to explain all these terms in the most straightforward way and with a very basic example. The technology introduces some new terms, which may be confusing when you first start using Docker. Your packaged software will always run the same in any platform where Docker runs.

Unlike VM's, containers do not contain platform software, so they are very lightweight and portable. Basically, it allows you to package software in a way that's conceptually similar to a Virtual Machine. Docker is a software container service which has become quite popular when deploying applications.