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Re: Systemd services (was Re: If Linux Is About Choice, Why Then ...)

On Thu, Apr 13, 2017 at 10:01:25PM +0100, Jonathan de Boyne Pollard wrote:
> ... albeit poorly.  If one wants to run daemontools under systemd, svscanboot is
> not the way; svscanboot is a thing of the past
> http://jdebp.eu./FGA/inittab-is-history.html#svscanboot , and was a source of
> problems long before systemd was invented.

Cool.  I wish my Google searching had stumbled upon that, when I was
trying to figure out how to do all that stuff.

> The world wants you to clean your screen
> http://unix.stackexchange.com/a/233855/5132 , and this is merely one of the ways
> that it makes you do so.

Some day there will be actual end-user-friendly systemd documentation
somewhere, consolidating all of these pieces of wisdom together.  I hope.

My own contributions toward that effort have been riddled with failure and
confusion, for which I am sorry.  I'm honestly *trying*, but this stuff is
really opaque at times.

For instance, just this week I learned three new things:

1) To override parts of a distribution's systemd unit locally, you MUST
   use the foo.service.d/ method.  You can't just put the override bits
   into an /etc/systemd/system/foo.service file.  That would be too easy.

2) The files inside foo.service.d/ MUST end with a .conf suffix.  (Cf.
   the wheezy->jessie apache2 upgrade, and having to rename every single
   one of my virtual domain config files AND the symlinks to them.)

3) foo.service.d/ must use the CANONICAL service name of whatever it is
   that you're trying to override.  This may not be the same as the
   Debian package name.  For example, the nfs-kernel-server package
   creates a systemd unit named nfs-server.service with an ALIAS of
   nfs-kernel-server.service.  If you try to create override files in
   nfs-kernel-server.service.d/ it will not work correctly.  They have
   to be in nfs-server.service.d/ instead.

   Don't even get me started on sshd.service vs. ssh.service.  Do you
   have any idea how hard it is to notice that extra/missing "d", and
   figure out why things Simply Do Not Work?