A program which queries the local metadata server for GCP Cloud Run.
More info on which data can be queried is located here: https://cloud.google.com/run/docs/reference/container-contract#sandbox
gcloud run deploy metadata --allow-unauthenticated --source .
The target directory (which included the executable) was not being copied over to Google Build.
The gcloud CLI was dynamically building a .gcloudignore file, and the target directory was in the list (due to being listed in .gitignore), thus being excluded from the build process.
See: https://cloud.google.com/sdk/gcloud/reference/topic/gcloudignore
Useful command: gcloud meta list-files-for-upload