I'm currently working on splitting our phab daemons out across multiple machines, per:
As part of that work, I have discovered that it is possible that phd-daemon process can die, leaving our daemon processes unsupervised. Thus, we would like to have process supervision/monitoring for the phabricator daemon processes. We currently use daemontools for this, but unfortunately daemontools assumes that it will be doing the daemonizing.
And thus we arrive at the feature request. Currently the only way to make a phabricator daemon run in the foreground is to use the debug argument to phd. But this also routes all log data to stdout, which isn't what we want. Instead, something like phd launch --foreground <daemon type> seems ideal. This will allow the supervisor to handle the daemonizing, and keep logging going to the usual place.
I have a rough patch that adds this functionality, that I'd be happy to contribute.