What is the purpose of a Dockerfile?

The purpose of a Dockerfile is to define the environment for a Docker image. A Dockerfile is essentially a script that contains a series of commands and instructions, which Docker uses to automate the building of images. This includes defining the base operating system, installing necessary dependencies, configuring the environment, and specifying how applications should be run within that image.

When a Dockerfile is executed with the docker build command, it translates the defined steps into a Docker image. This image encapsulates everything needed for an application, including the code, libraries, and tools, thus ensuring that it can be reliably run in various environments without conflicts or variability.

The other options do not accurately reflect the primary function of a Dockerfile. Managing Docker containers typically involves using Docker commands or Docker Compose files, running commands in a container pertains to the process of executing commands directly within an already running container, and listing all Docker images is done using specific Docker commands and not defined within a Dockerfile.