What is a GitLab Runner primarily used for?

A GitLab Runner is primarily used for executing jobs defined in a configuration file, typically in YAML format, known as the .gitlab-ci.yml file. This file specifies the various tasks that need to be performed as part of the CI/CD (Continuous Integration/Continuous Deployment) process. The Runner takes the defined jobs and runs them in isolated environments, which could be a Docker container, a virtual machine, or directly on a physical machine. This execution is crucial for automating the testing, building, and deployment of applications, allowing developers to streamline their workflows and increase efficiency.

The role of the GitLab Runner is central to the automation capabilities of GitLab CI/CD, making it a vital component when setting up Continuous Integration pipelines. By correctly interpreting the jobs specified in the YAML file and executing them, the Runner helps maintain the integrity and quality of code through automated processes, ensuring that every change is tested and validated before integration into the main codebase.