[Pkg-systemd-maintainers] Bug#619244: /etc/machine-id

[Michael Stapelberg]

Hi Josh,

Josh Triplett <josh at joshtriplett.org> writes:
> On the other hand, I'm somewhat curious what upstream actually *uses*
> the machine-id for, and why a machine needs a unique identifier.
The only use of the machine-id in Debian that I could find is within the
journal:

http://sources.debian.net/src/systemd/44-12/src/journal/journal-file.c?hl=130#L130

Given that the file replaces the old DBus machine-id, if you consider
that, we have a few more calls in the archive:

http://sources.debian.net/src/consolekit/0.4.5-3.1/src/ck-manager.c?hl=306#L306
http://sources.debian.net/src/kaa-base/0.6.0+svn4596-1/src/utils.py?hl=291#L291

Also, http://www.freedesktop.org/software/systemd/man/machine-id.html
explains:

  Programs may use this ID to identify the host with a globally unique
  ID in the network, which does not change even if the local network
  configuration changes. Due to this and its greater length, it is a
  more useful replacement for the gethostid(3) call that POSIX
  specifies.

While this is not a totally satisfactory answer, I hope it clarifies the
intention of this ID.

-- 
Best regards,
Michael