Continuous integration and continuous deployment in GitLab is described and defined by a project's .gitlab-ci.yml file. The file format is YAML (an acronym of yet Another markup language), which is a human-readable text file that's used for storing data, and can be converted into digital representations by a computer. This document is stored in the root directory of your repository and outlines all of the stages and work required for the CI/CD to run.
A basic .gitlab-ci.yml file might look something like this:
before_script: - apt-get update -qq && DEBIAN_FRONTEND=noninteractive apt-get install -y -qq ca-certificates git php php-xml - php -r "copy('https://getcomposer.org/installer', 'composer-setup.php');"