What is the purpose of a Dockerfile?

The function of a Dockerfile is to establish a set of instructions used to create a Docker image. This file contains the necessary commands to assemble the environment, including the operating system, libraries, dependencies, and application code. When Docker builds an image from the Dockerfile, it follows these instructions in sequence, ensuring that the resulting image contains everything needed to run the application smoothly in a containerized environment.

Building a Docker image is a fundamental aspect of using Docker, as images serve as the blueprints from which containers are instantiated. Since containers themselves are ephemeral and do not retain the same state across runs, the Dockerfile ensures that the required setup is consistently recreated, facilitating reproducibility and ease of deployment across different environments.