What is the difference between cmd and entrypoint in a Dockerfile?

The correct answer highlights that CMD sets default arguments, while ENTRYPOINT configures the behavior of the container.

In a Dockerfile, ENTRYPOINT is designed to specify the command that will always be run when a container starts. It establishes the base command or executable that the container will execute, making it a fundamental aspect of how the container operates. This allows it to behave like an executable, where passing command-line arguments directly impacts its functionality.

On the other hand, CMD provides default arguments that can be passed to the ENTRYPOINT command or specifies a command to run when the container is started without any arguments. You can override these default arguments at runtime, allowing for greater flexibility while still adhering to the constant behavior defined by the ENTRYPOINT.

Thus, the distinction between the two is critical for structuring Docker containers in a way that ensures both predictable and flexible behavior depending on the task at hand. There are notable use cases for each: ENTRYPOINT is typically used to define the main application process, whereas CMD is best utilized for specifying parameters or defaults that can be adjusted during container execution.