By Jonathan Corbet
July 31, 2013
The Fedora distribution prides itself on its image as a leading-edge Linux
distribution
where new stuff shows up first. But, as some developers recently
discovered to their chagrin, that image does not necessarily extend to
deleting features first. After an extensive debate, the Fedora project has
decided, for now, to retain the sendmail mail transfer agent — a program
that is many years older than Linux — in the default installation. Whether
this outcome is a victory for Fedora's "stone age faction" or a careful
defense of Fedora's Unix tradition is very much in the eye of the beholder.
The no
default sendmail proposal, intended for the Fedora 20 development
cycle, had a simple goal: remove sendmail from the "core" and "standard"
package groups, so that sendmail would not be installed by default in
Fedora's minimal or desktop configurations. Sendmail would, of course,
remain as an option for anybody who wanted to install it separately. The
simplest ideas are often those most subject to discussion, though; in this
case, the proposal set off an
email thread that was epic even by the standards of the Fedora
development list.
The proponents of the change (Lennart Poettering and Matthew Miller) argued
that there was little use for a mail transfer agent (MTA) installed by
default. On today's Internet, there is no way to configure an MTA so that
it comes up in a working configuration by default. Many or most Fedora
users run in a situation where mail cannot be sent directly from (or to) their
systems anyway, due to Internet service provider blocking policies and
anti-spam measures taken at remote sites. Sendmail is set up to deliver
mail into /var/spool/mail — a location that no
mail user agent in the default Fedora install reads. So, it is said, there
is little value in having sendmail around.
Going on, they argue that there are some costs to installing sendmail by
default. Sendmail's time as a constant
source of severe security problems is long past, but it is still a
privileged program that need not be installed much of the time. Removing
sendmail would reduce the distribution's disk space requirements and
decrease system
boot time. Ubuntu has not installed an MTA by default for years; systems
like Mac OS X also install without an MTA. And in the end,
Lennart and Matthew argued, even if Fedora were to install an MTA by
default, sendmail is a bit of a peculiar choice.
The opposition to the proposal is a bit harder to summarize. A number of
participants cited the fact that cron jobs send email if they
produce unexpected output. In the absence of an MTA, that output goes
instead to the system log which, for some, is a place where it can get lost
in the noise. Miloslav Trmač suggested
that the /usr/sbin/sendmail binary forms a sort of API by which
applications can reliably send email; in its absence, those applications
would have to grow their own SMTP implementations, which might not lead to
a better system overall.
Some of the arguments against the removal of sendmail expressed a vague
feeling that an MTA is an important and traditional component of a Unix
system. Removing sendmail would take Fedora (further) away from that
tradition, making some people uncomfortable. Having sendmail in the mix
does not bother people who are not using it, they said, and anybody who
really objects to its presence can always uninstall it. So, rather than
making such a fundamental change to the system, it would be better to come
up with a better set of default configurations for the mail transfer and
user agents installed with the distribution.
The discussion went back and forth for some time while, seemingly,
convincing few of the participants. Some Fedora users evidently value
getting cron output in email, while others point out that, on most
systems, it piles up unnoticed in /var/spool/mail and might as
well be discarded. For the latter camp, the logging subsystem is clearly a
better way for system daemons to communicate results to users or
administrators, but discussions around the logging system tend to turn into
an
even bigger can of worms in short order. Arguments based on
tradition almost never get anywhere with those who are determined to change
that tradition — or leave it behind altogether.
The Fedora Engineering Steering Committee (FESCo) met on July 24 to (among other agenda
items) make a decision on this issue. The discussion there was rather
shorter; it can be found in the
IRC log. In the end, the board voted unanimously to remove sendmail
from the minimal "core" group. When it came to the "standard" group (which
is what matters for most installations), though, the proposal faltered,
eventually failing on a 4-4 vote after Matthew, despite having proposed the
change, abstained from the actual vote as a gesture of respect for those
who wanted to take a slower, more careful approach. So a Fedora 20 desktop
installation will include sendmail.
It is fair to say that Lennart did
not react well to the decision:
If FESCO decides that Fedora's home is the stone age, then that's
fine, I don't think I have to care anymore. They should really
drop the "F" for "First" though from their 4-F motto, it's a blunt
lie. Fedora is seldom first on anything non-trivial, anymore. It is
just another conservative distribution. Sendmail is just the
pinnacle of it. I mean, really? sendmail???
In truth, some progress has been made toward Lennart's goal, and some
developers have expressed an interest in trying again for the
Fedora 21 development cycle.
Fedora, as a Linux distribution, does have a lot of roots in the Unix
tradition. It also has a number of users who have been with the
distribution (and its predecessor, Red Hat Linux) for a very long time.
Ways of working that have been established over decades can be awfully hard
to change, especially when the people involved see no reason why they
should change. It is, thus, unsurprising that the people who are trying to
drive significant changes run into a certain type of conservatism at times.
What matters is how the system evolves over the long term. There are few
who would say that Unix (or Linux) in any of its forms is the pinnacle of
computing. The Linux systems we use ten years from now will certainly look
quite different from what we have now — either that, or we'll not be using
Linux at all. Chances are that distant-future Linux distributions will not
have sendmail installed by
default. In the meantime, though, proponents of change can expect to have
to work through some resistance at times; that is, after all, how human
communities work.
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