The canonical web url must be set. Optional base URL for repositories available over the anonymous git protocol. For example, set this to git://mirror.example.com/base/ to have Gerrit display patch set download URLs in the UI. Gerrit automatically appends the project name onto the end of the URL.
By default unset, as the git daemon must be configured externally by the system administrator, and might not even be running on the same host as Gerrit.