/etc/issue is far from being a reliable source for OS detection as it
can be changed by a user without affecting any OS functionality. As
newer Debian systems run systemd by default, check for /etc/os-release
and fallback to lsb_release for older Debian versions. Check #7625 for
a similar issue. Even lsb_release is not manatory, therefore keep the
current code of parsing /etc/issue to avoid regressions.
This updates the guest capabilities to run in as few communicator
commands as possible. Additionally, it fixes a number of issues around
hostname and idempotency.
This patch was tested against:
- puphpet/debian75-x64
- debian/jessie64
- debian/wheezy64
with custom networking, custom hostname, and rsync shared folders.
When dealing with lxc containers, '/proc/version' will have information
about the host machine kernel that can possibly have information about
an Ubuntu / Debian host, messing up with guest container detection.
On Debian systems config.hostname directive should change /etc/mailname
in order to prevent problems with default mailer trying to contact
default vm's name.
I don't use `activated` here because I'd really like to optimize
performance as much as possible, and loading files from disk is
generally slow. So instead of using `activated` I load the file at the
last possible moment which is when the exact class is being requested.
I don't think many people will do this outside of the core, and I'm not
too concerned.