What file format is used for defining Docker Compose files?

Docker Compose files are defined using the YAML format. YAML, which stands for "YAML Ain't Markup Language," is a human-readable data serialization format that is particularly well-suited for configuration files. In the context of Docker, YAML files provide a straightforward way to define the services, networks, and volumes that make up a Docker application, allowing users to structure and organize their containerized applications in an accessible manner.

YAML's indentation-based syntax enhances readability and allows for a clear representation of hierarchical data structures, which is essential when defining the various components and their configurations in a Docker environment. This makes it easier for developers to understand and maintain their setups, leading to improved collaboration and efficiency in managing services.

Other formats, such as JSON, XML, and HTML, are not commonly used for Docker Compose files. While they can express similar data structures, they lack the simplicity and clarity that YAML offers for this specific purpose. JSON can be more verbose and harder to read, XML is often cumbersome with its tags, and HTML is a markup language intended for structuring web pages, not for configuring software services. Therefore, YAML is the preferred and standard format for defining Docker Compose files.