[mosquitto-dev] Duplicated log when using upstart>=1.4 can break systems

[Mikkel Kirkgaard Nielsen <miki@xxxxxxxxx>]

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Hi stingers/stung people.

Today I experienced an Ubuntu 14.04 development system break using
Mosquitto v1.4.5 installed from PPA.
It had accumulated a ~4GiB log file in /var/log/upstart/mosquitto.log
that deprived the system of available diskspace.

I was able to trace it back to the fact that the mosquitto server was
outputting log messages both to the configured "log_dest file
/var/log/mosquitto.log" and to stderr.
The startup daemon will by default (since upstart v1.4, see
http://upstart.ubuntu.com/cookbook/#id152) save stderr from spawned
daemons to files in /var/log/upstart/ thus duplicated logging will be
done. This can be problematic if no rotation is done on
/var/log/upstart (this seems luckily to be the default on our servers).

As I recall the distributed mosquitto.conf for Ubuntu (and Debian?)
(which is not identical to what I see today in git) it is set up like
that too.

It can be fixed in configuration by turning off the default "stderr"
logging before specifying the log method you actually want by
inserting a "log_dest none" clause before other "log_dest" clauses.
Or it could be prevented by using the --daemon switch when exec'ing in
upstart configuration. Any reason why this isn't done already?

A minor issue but one that is critical for the people where it rears
its head. At least a sane default config should not duplicate logs
like that.

I see other people has had similar problems;
https://github.com/jpmens/mosquitto-auth-plug/issues/54

- -- 
    Mikkel

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