What is the purpose of 'docker-compose' in Docker?

The purpose of 'docker-compose' is to define and manage multi-container applications. Docker Compose allows you to configure all the different services that make up an application in a single YAML file. This includes settings like the images to use, the ports to expose, environment variables, and any dependencies between services.

When you use Docker Compose, you can easily launch all the containers defined in the configuration file with a single command. This is particularly useful for applications that require multiple services, such as a web server, a database, and a caching layer, which can all be orchestrated together. It simplifies the process of running these containers, ensures consistent environments, and enables efficient deployment practices, especially in development and testing scenarios.

In contrast to other options, running individual containers or managing Docker volumes represents tasks that are not the main focus of Docker Compose. Monitoring container performance is also outside the scope of what Docker Compose is designed to do. This makes the ability to define and manage multi-container applications the primary and correct function of Docker Compose.