Fix and clean up systemd tgt.service unit file

[JohnAZoidberg]

The service would fail to run for me. This makes it work and also nicer. See commits:

tgtd.service: Wait for tgtd to be ready
    If we don't wait, it fails with:
    tgtadm: failed to send request hdr to tgt daemon, Transport endpoint is
    not connected

    It's not a pretty solution but CentOS and Fedora do the same workaround.

Kill tgtd after targets were deleted
    Otherwise the daemon will keep running.

Remove getty comment
    getty does not seem to be related to this service.

Run tgt-admin verbose
    So that it shows all the underlying tgtadm commands it executes.
    Makes debugging easier.
    Also expand the arguments to their full form so that it's clearer what
    each command does.

tgtd.service: Don't fork but notify
    Let systemd handle the process management.
    Type=notify so that the ExecStartPost commands are only executed when
    the daemon is ready.

Fix Documentation URI
    systemd issues a warning with the space present.

Maybe you can suggest a better way to wait for tgtd to become ready?

[gonzoleeman]

This is kind of ugly. Why not make tgtd only signal systemd is's ready when it's actually ready (using sd_notify())?

[JohnAZoidberg]

I forgot about sd_notify, thanks! tgtd even already implements this https://github.com/fujita/tgt/blob/master/usr/tgtd.c#L659

[rdxmb]

are you sure this is needed? I run tgtd with foreground in a container. And stopping it via https://github.com/fujita/tgt/pull/41/files#diff-f589b6bd883ba54cbe2ebfc7b864d73fde17e245a48cf272fcf8dc9b37ac4969R19-R21 definitely stops the whole process.