This is how:
import com.atlassian.confluence.setup.settings.SettingsManager import com.atlassian.sal.api.component.ComponentLocator SettingsManager settingsManager = (SettingsManager) ComponentLocator.getComponent(SettingsManager) String baseUrl = settingsManager.getGlobalSettings().getBaseUrl()
I often use it like:
if (baseUrl.contains("test"))
{
//We are in test environment
}
else
{
//We are in prod environment
}