To make sure there are no services ingested into Cortex without a valid service tag, a Service YAML file will not be processed in Cortex if the file is invalid. GitLab does not automatically lint these files.
To ensure your Service YAML is accurate, Cortex also has a built-in linter that you can use. Alternatively you can use a dry run linter in your CI (continuous integration). Check out our docs on dry run setups for an API that will return linter errors, allowing you to take any required action.
Cortex also has built-in validation for invalid service tags, including bad characters and another repo already has the same tag. Please note: The Github App is needed for this feature. We will also apply validation as a PR-time check so that it's not a blocking validation (because it may be semantically correct with the new tag). The Github App will comment on the PR with the linter errors.
At this time, there is no way to filter out repos in GitHub using regex before it comes to Cortex.