No MTA
Summary
Make the MTA (i.e. /usr/sbin/sendmail
) optional.
Owner
- Name: Adam Miller
- email: maxamillion [AT] gmail.com
Current status
- Targeted release: Fedora 13
- Last updated: 23 March 2010
- Percentage of completion: 90%
Working:
- Everything as designed (Aside from messages that would normally be sent via a MTA)
Done:
- Patch
to redirect messages that would be sent to a MTA to syslog in the event a MTA is not present.cronie
- Patch submitted in RHBZ #548843, applied to cronie-1.4.4, currently in F13.
- Add sendmail to comps to ensure it is still installed by default, as expected
sendmail
is listed in thebase
group.- This is for compatibility purposes and should be removed in a future release
TODO:
- Add comment to
/etc/sysconfig/crond
that shows how to use syslog instead of sendmail:
# To send cron output to syslog instead of local mail, set CRONDARGS to: #CRONDARGS="-s -m off"
- Remove cronie's hard requirement on
/usr/sbin/sendmail
- Patch the default configuration for logwatch to not send mail, but to send messages to stdout and then verify the patch to cronie is reporting logwatch messages to syslog accordingly.
- Verify there are no other packages that will require a patch to function without a MTA
Detailed Description
The presence of a Mail Transfer Agent (MTA) like sendmail
has long been the de facto standard. But most systems that aren't mail servers do not specifically need to keep local mail queues or transfer mail to other systems. For the vast majority of users this is simply wasted resources and wasted disk space for the packages installed.
cron
is the only thing in a default Fedora install that still uses local mail to report its status. The cron
syslog facility exists for this purpose, and our current cron
setup already uses it[1] to log some messages[2] to /var/log/cron
.
This feature allows cron
to optionally use syslog instead of email to report job status, thus making the presence of an MTA completely optional.
Benefit to Fedora
One less required package in the critical path, and we clear the way for removing the MTA from the default install.
Scope
Packages that may require changes:
cronie
cronie
is the only package in a default Fedora install that requests the use of an MTA. If /usr/sbin/sendmail
is not present, it will simply stop sending mail. Therefore, if we modify cronie
to send job output to a log file, we can remove the requirement for an MTA with no loss of functionality.
Required changes:
- Modify
cronie
to send job output to thecron
syslog facility ifsendmail
is missing - Remove
Requires: /usr/sbin/sendmail
from
's spec filecronie
crontabs
crontabs
need to be examined to be sure none of them depend on local mail being sent.
logwatch
logwatch
needs to be examine to see if it actually depends on cron sending email, and patched to use stdout/syslog if so.
How To Test
- Ensure you have
cronie-1.4.4-1.fc13
or higher installed. - Edit
/etc/sysconfig/crond
and setCRONDARGS="-s -m off"
service crond restart
yum remove sendmail
(or whichever package is providing your/usr/sbin/sendmail
)- This step won't work yet - cronie-1.4.4-1.fc13 still requires
/usr/sbin/sendmail
. Skip it for now.
- This step won't work yet - cronie-1.4.4-1.fc13 still requires
- Verify that all output from cron jobs shows up in
/var/log/cron
User Experience
Transparent to most users. System administrators or integrators who were relying on the implicit dependency on /usr/bin/sendmail
may need to update their kickstart files etc. to explicitly install their chosen MTA.
Dependencies
none
Contingency Plan
Do Nothing.
Documentation
- None
Release Notes
- None
References
- ↑
/usr/bin/run-parts
runs all the cron jobs in/etc/cron.{hourly,daily,weekly,monthly}
- see/etc/cron.d/0hourly
(which runs the jobs in/etc/cron.hourly
) and/etc/anacrontab
(which launches the daily/weekly/monthly jobs.) - ↑ In fact, our current setup does not log the output of cron jobs to
/var/log/cron
- this feature would fix that.
Comments and Discussion