Ubuntu and Upstart
A while back Ubuntu switched from the classic bash script disaster know as SysV to upstart. I won’t even get started on how terrible SysV was, but it was pretty bad as it was all shell scripts, no dependencies, no events, no parallelization, no integrated process monitoring, cgroups, etc.
I’ve used systemd before both in Fedora and embedded systems based around openembedded and loved it. It seems more natural and powerful then upstart. Upstart is what I have in Ubuntu (at least until I switch back to Fedora). So that’s what I’ll use today.
Bottom line is upstart is better then most init/process managers, with the exception of systemd. Specifically I’m talking about the ghetto shell or scripted process manager you wrote because you didn’t know any better… Ahem, I mean what I wrote.
Additionally upstart will respawn daemons that die and manages logging stdout and stderr to some place useful (
~/.cache/upstart for user session), manage stdout/stderr for logging, support for asynchronous events, etc.
Fixing My Mess
A while back I wrote a blog post about imapfilter. In that post I complained that imapfilter’s daemon mode is useless as it terminates and exits when it encounters IMAP server errors. After that my email is no longer filtered and I’m upset. I then wrote a simple and quick python wrapper to babysit imapfilter. Everything worked pretty well, but it all still felt wrong.
Today I got annoyed with the wrapper and autostart stuff so I removed it and re-implemented it upstart. Now upstart handles starting imapfilter in the first place and respawning it when it dies. Two birds, one stone.
Enabling Upstart User Sessions
First we need to enable upstart user sessions so that upstart fires up for my user when I login to the desktop. I found a blog post about Ubuntu user sessions that was very helpful. In a nutshell you need to do the following and then re-login to Ubuntu:
sudo sed -i 's/^#ubuntu/ubuntu/' /etc/upstart-xsessions
Setting up imapfilter
Place the following in
description "imapfilter" author "Kyle Manna <[email protected]>" # Start after keyring registers on dbus start on started dbus #stop on desktop-end # Automatically restart process if crashed respawn # Log this job's stdout to ~/.cache/upstart/<name>.log # default is console log #console log # Start in foreground mode so it can be properly managed exec imapfilter -v
Now upstart will take of the rest. It will setup the DBUS_SESSION_BUS_ADDRESS environment variable that the imapfilter python and lua scripts need set for accessing the user’s key chain. All magic, to start that magic run the following:
Imapfilter is now stated and all it’s output will be in
~/.cache/upstart/imapfilter.log. An easy way to monitor it for debugging is
tail -f ~/.cache/upstart/imapfilter.log. Double check that upstart thinks imapfilter is running with:
$ initctl status imapfilter imapfilter start/running, process 3459
And since the
start on started dbus is in the job config file, the imapfilter task will be auto started every time the user logs in to the Ubuntu desktop session. Logging in to the desktop session. Set it and forget it.
Upstart user session jobs:
$ initctl list xsession-init stop/waiting imapfilter start/running, process 3459 dbus start/running, process 3458 gnome-session start/running, process 3482 ssh-agent start/running logrotate stop/waiting im-config start/running upstart-file-bridge start/running, process 3468 gnome-settings-daemon start/running, process 3481 re-exec stop/waiting upstart-event-bridge start/running, process 3463
Upstart user session global environment:
$ initctl list-env DBUS_SESSION_BUS_ADDRESS=unix:abstract=/tmp/dbus-vGmn0j3MRp GNOME_DESKTOP_SESSION_ID=this-is-deprecated INSTANCE= JOB=dbus PATH=/home/nitro/bin:/usr/lib/lightdm/lightdm:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games SESSIONTYPE=gnome-session SESSION=ubuntu SSH_AGENT_PID=3460 SSH_AUTH_SOCK=/tmp/ssh-ZlMOWJzORL00/agent.3457 UPSTART_EVENTS=started xsession