The core of our new project runs on Node.js. With Node you can write very fast JavaScript programs serverside. It's pretty easy to install Node, code your program, and run it. But how do you make it run nicely in the background like a true server?

Clever chaps will have noticed you can just use the '&' like so:

node ./yourprogram.js &

and send your program to the background. But:

if Node ever prints something and your console is closed, the STDOUT no longer exists and yourprogram.js will die
what if the process crashes, what if your server reboots?

Ok, so we needed something more robust. More like a real daemon, one that's recognized by the Operating System as such.

upstart

Our servers run Ubuntu's latest: Karmic Koala, which packs a pretty decent version of upstart. Upstart will eventually replace the well-known /etc/init.d scripts, and will bring some additional features to the table like: speed, health checking, simplicity, etc.

Writing an upstart script

Turns out, writing your own upstart scripts is way easier than building init.d files based on the /etc/skeleton file.

Ok so here's how it looks like; You should store the script in /etc/init/yourprogram.conf, create one for each Node program you write.

description "node.js server"
author      "kvz - http://kevin.vanzonneveld.net"
 
# used to be: start on startup
# until we found some mounts weren't ready yet while booting:
start on started mountall
stop on shutdown
 
# Automatically Respawn:
respawn
respawn limit 99 5
 
script
    # Not sure why $HOME is needed, but we found that it is:
    export HOME="/root"
 
    exec /usr/local/bin/node /where/yourprogram.js >> /var/log/node.log 2>&1
end script
 
post-start script
   # Optionally put a script here that will notifiy you node has (re)started
   # /root/bin/hoptoad.sh "node.js has started!"
end script

Dont forget to chmod u+x your file so it will be executable.

Wow how easy was that? Told you, upstart scripts are childsplay. In fact they're so compact, you may find yourself changing almost every line cause they contain specifics to our environment.

non-root

Node can do a lot of stuff. Or break it if you're not careful. So you may want to run it as a user with limited privileges. We decided to go conventional and chose www-data.

We found the easiest way was to prepend the Node executable with a sudo like this:

exec sudo -u www-data /usr/local/bin/node

Don't forget to change your export HOME accordingly.

Restarting your Node.js daemon

This is so ridiculously easy..

start yourprogram
stop yourprogram

And yes, Node will already:

automatically start at boottime
log to /var/log/node.js

..that's been defined inside our upstart script.

initctl

But wait, start and stop are just shortcuts. Who's really behind the wheel here, is initctl. You can play around with the command to see what other possibilities there are:

initctl help
initctl status yourprogram
initctl reload yourprogram
initctl start yourprogram # yes, this is the same start

etc

More on Node.js

With Node you can write very fast JavaScript programs serverside. We've seen examples of chat, key-value store, and full blown http servers. Basically anything is possible as long as you know JavaScript and the concepts of parallel/evented processing. You don't? Well if you've ever used setTimeout(), you'll soon get the hang of it ; )

Node.js video presentation by creator Ryan Dahl
Node.js slides that accompany the presentation
About Node on the official website
Node.js is genuinely exciting by Simon Willison
node.js by Debuggable

You probably shouldn't follow me

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tags: nodejs, ubuntu, karmic, upstart, daemon, transloadit, php
category: Programming - Javascript - Node.js
read: 53,280 times

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Comments

#33. Andy on 27 January 2012

Do you think this could work on CentOs?

#32. Rindra on 14 December 2011

Hi,

First i would like to say that this works really great as is. Thanks a lot!
Now I've tried to use the upstart script with a static file server I've created with node.js
When I run it from the terminal: node main.js everything works fine in the browser. The issue occurs when i start my server as a daemon, start app, nothing appears in the browser.
... [more]
I'm starting on node.js and i love the platform, so is this a misconception on my end? I would love to get your input on this.

Thanks again!

#31. claude hussenet on 27 November 2011

Works like a charm !

Claude Hussenet

#30. Mauvis Ledford on 18 September 2011

Just a note that I followed your directions on Ubuntu 11.04 and everything worked except for on reboot.

With some research I ended up modifying this line to get it working:

from: start on started mountall
... [more] tp: start on (local-filesystems and net-device-up IFACE=eth0)

I guess, the internet wasn't ready when the script was executing.

Cheers,

Mauvis

#29. Herman A. Junge on 12 September 2011

Thanks a Lot. I was looking for an elegant solution to that problem.

hermanjunge

#28. dale on 07 July 2011

i can't seem to get this to work correctly. I have always type in `sudo start myapp` in order for this to start. So when i reboot my server, this script does not fire at all. I actually changed the user:group to my www-data:www-data user/group, and gave the file permissions of 774. but even with that, i still need to run sudo to get the file to start. any clues on what else i may be able to do to get this to start on server reboot?

#27. Geoff Wagstaff on 12 May 2011

Great write-up on getting upstart working. For those who want to have node processes persist after they close the terminal without upstart, you could use nohup:

nohup node script.js > /dev/null

#26. Aaron Fay on 04 May 2011

Simply awesome, thanks for the upstart info. Being able to 'restart node-app' is just bloody awesome.

Thanks,
Aaron

#25. Kevin on 17 April 2011

@ Eran Hammer-Lahav: Thanks, changed it.

@ Joey: Sure : ) I just like how small upstart scripts can be and that it can resuscitate crashed programs.

#24. Joey on 30 March 2011

Thanks for the init.d version, Peter!

For anyone (like me) running a server on an older distro release, using Upstart is either not possible, impractical, or overkill when you already have init.d.

And for anyone (again, like me) running a server on a new distro, you're at least as likely to have systemd (which will replace Upstart in the long run) available to you as you are Upstart.
... [more]
I think I'll stick with good ol' init.d (which is available & highly compatible on every distro I've installed) until the distros figure this out ;)

#23. Eran Hammer-Lahav on 17 March 2011

Should it be:

exec /usr/local/bin/node /where/yourprogram.js >>/var/log/node.log 2>&1

instead? The original version does not save exceptions to the log file.

#22. Kevin on 04 March 2011

@ peter host: Thanks for sharing. Keep in mind upstart will replace init.d in the long run though.

#21. ipage on 31 December 2010

This is what I have been looking for! Thanks for this helpful tutorial!

#20. peter host on 04 December 2010

Clear and to the point :)
As a complement for users who like it the init.d way :
https://gist.github.com/715255

#19. Ovidiu on 28 October 2010

Awesome tutorial, thank you, works really well!

#18. Kevin on 11 October 2010

@ hellcats: well try debugging it a little.
what happens when you just run

/usr/local/bin/node /where/yourprogram.js 2>&1 >> /var/log/node.log

... [more] what about:

/usr/local/bin/node /where/yourprogram.js ?

#17. watch hellcats online on 01 October 2010

copy-pasted the example, only replacing /where/yourprogram.js for my program - but after "sudo start myprogram" it must crash. Nothing is logged. Using upstart 0.6.3-11 on karmic.

#16. Sami Samhuri on 16 August 2010

Thanks Kevin! This is exactly what I needed.

#15. Kevin on 12 August 2010

@ AFire: Read more carefully. The first message your script sends to STDERR, and your terminal is closed, your script is killed. But you've probably figured that out, or resorted to using monit by now.

@ Xavier: The same way that I:
export HOME="/root"

... [more] You could export your PATH as well if that's required.
so first echo $PATH, and put that in there

#14. Xavier on 15 July 2010

For whatever reasons I cannot make it work. My program doesn't seem to run in the same environment and path.exists returns errors when node is launched via initctl.
I checked the require.paths array and it is exactly the same whether I run directly node app.js or if I do "start node".

I also tried to to run "env" before (sudo -u myuser env /usr/local/bin/node /path/app.js ...) but doesn't help.

... [more] I run out of ideas. Thanks for your support.

#13. AFire on 13 July 2010

node ./yourprogram.js | tee -a node.log &

#12. Kevin on 10 June 2010

@ Francisco: Did you get it working? As for the real-world program, here it is: http://transloadit.com/

#11. Francisco on 25 May 2010

I was being a bit silly, I fixed my program to be executable from an absolute path.

I copy-pasted the example, only replacing /where/yourprogram.js for my program - but after "sudo start myprogram" it must crash. Nothing is logged. Using upstart 0.6.3-11 on karmic.

#10. Francisco on 25 May 2010

Thanks for the write up!

Hey guys did you manage to run a real-world program? Mine requires a library with a relative path so I can't call it from anywhere (like, node /path/to/my.js).

I either need to cd /path/to && node my.js , or use chdir - but none has worked for me. Any ideas?

#9. Kevin on 26 February 2010

@ George: Cool thanks for sharing!

#8. George on 25 February 2010

Thanks for this, worked like a charm.

The only thing I had to change was that I change to the directory containing my .js file before launching node. For whatever reason, I otherwise have trouble loading static files into my node.js app.

Cheers!

#7. Kevin on 07 January 2010

@ jz: Correct, I actually had to change it from /etc/event.d to /etc/init/ when we upgraded to Karmic. It looked as if they were going to stick with /etc/init in the long run though, so be prepared to change it back at one point ;)

#6. jz on 25 December 2009

thanks for the writeup!

for some reason, on 8.10 i had to put the conf file in /etc/event.d for initctl to find it...

#5. sveisvei on 16 December 2009

Useful stuff, thanx :)

#4. Kevin on 15 December 2009

@ Mariano Iglesias: Hey. That's a trick I didn't know yet, thanks a lot Mariano!

#3. Mariano Iglesias on 15 December 2009

@Felix: also, if you want to run a script in background, and not link it to your session (so if you logout it doesnt die), use nohup:

$ nohup script &

#2. Kevin on 15 December 2009

@ Felix Geisendörfer: Thanks for adding some sugar to the post! While screen won't give you healthchecks, or come online when your server recovers from a crash, it's definitely another great tool in our arsenal!

#1. Felix Geisendörfer on 15 December 2009

Cool article Kevin, glad you published this : )!

If you just need something slightly better than "node ./yourprogram.js &", because you might just be doing a long running job, you can type in "screen" and then execute "node ./yourprogram.js" in the new terminal that opens. Screen sessions don't die if you log out, and you can even re-attach them using "screen -r" when you login the next time.