‘gitlab-ci-mode’ is a major mode for editing GitLab CI files.  It
provides syntax highlighting and completion for keywords and special
variables.  An interface to GitLab’s CI file linter is also provided
via ‘gitlab-ci-lint’.

For more information about GitLab CI, see URL
‘https://docs.gitlab.com/ce/ci/README.html’.  For details about the
file format, see URL
‘https://docs.gitlab.com/ce/ci/yaml/README.html’.