[systemd-devel] Query regarding "EnvironmentFile"

[Simon McVittie]

On 09/12/15 19:46, Lennart Poettering wrote:
> Also /etc/sysconfig is a Redhatism
> that should really go away, the whole concept is flawed.

This is by no means limited to Red Hat derivatives: /etc/default is a
Debianism which is basically the same as /etc/sysconfig.

I think Red Hat and Debian derivatives do both over-use their respective
EnvironmentFile directories (and in particular the START_DAEMON=0
anti-pattern, which was a workaround for how hard it traditionally was
to disable a service in sysvinit, needs to go away), but it can make
sense for the specific case of overriding non-system-integration-related
command-line options, to avoid situations like this:

* foobar version 1 has ExecStart=/usr/libexec/foobar --no-fork
* sysadmin overrides that to
  ExecStart=/usr/libexec/foobar --no-fork --enable-uploads
* distribution or upstream changes version 2 to say
  ExecStart=/usr/libexec/foobar --no-fork --use-syslog
  (or some other new system-integration option)
* desired result: --no-fork --use-syslog --enable-uploads
* actual result if the sysadmin has used systemctl edit:
  --no-fork --enable-uploads

by having "ExecStart=/usr/libexec/foobar --no-fork [--use-syslog]
$OPTIONS" instead.

Of course, it would be better for the underlying service to have a
configuration file (or, better, a .d directory) where the sysadmin could
enable uploads; but we have to work with what we have, not what we'd
like to have, and not all underlying services have that.

The approach I try to follow in dbus is that options that should be
changed by another package (such as default security policies) go in a
configuration file, or more recently a file in /usr/share; options that
should be changed by the sysadmin (such as security policies and
resource limits) also go in a configuration file; but system-integration
options (such as "use syslog" or "use systemd for activation") are
command-line options that can be forced to their
correct-for-this-distribution values by the ExecStart line in the
systemd unit, LSB init script or whatever. Unfortunately dbus doesn't
always follow this rule for historical reasons - <syslog/> is a
configuration-file option, but it shouldn't be.

-- 
Simon McVittie
Collabora Ltd. <http://www.collabora.com/>