How to change the default upstart log directory?

I have some upstart-started apps which log a lot of stuff... I want to be able to choose in which directory the upstart logs will be saved. The default is /var/log/upstart.

In the upstart docs, they say I should give upstart a command-line option --logdir.

However, upstart is started as a daemon process by the OS as far as I know, so how can you even give it command-line arguments?

Solution

The upstart process is executed by the kernel at system boot. You can configure the command to be used by the kernel using a kernel command line argument. It should look like this:

init=/sbin/init --logdir=/path/to/logfiles

While you can configure grub to pass that command line option to the kernel, you also use a simple wrapper script for that.

Copy the original init binary to a backup:

sudo cp /sbin/init{,.orig}

Then create the wrapper script:

/sbin/init:

#!/bin/bash

# Pass modified logdir option
init.orig $@ --logdir=/path/to/logfiles

And make it executable:

sudo chmod +x /sbin/init