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
- 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.
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 advantages 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
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
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.
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
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
..that's been defined inside our upstart script.
stop are just shortcuts. Who's really behind the wheel
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
Update from October 30th, 2012
The basic idea has not changed since 2009, but we did add some tricks to our upstart script. Here's what we now use in production at transloadit.com:
# cat /etc/init/transloaditapi2.conf # http://upstart.ubuntu.com/wiki/Stanzas description "Transloadit.com node.js API 2" author "kvz" stop on shutdown respawn respawn limit 20 5 # Max open files are @ 1024 by default. Bit few. limit nofile 32768 32768 script set -e mkfifo /tmp/api2-log-fifo ( logger -t api2 </tmp/api2-log-fifo & ) exec >/tmp/api2-log-fifo rm /tmp/api2-log-fifo exec sudo -u www-data MASTERKEY=`cat /transloadit/keys/masterkey` /transloadit/bin/server 2>&1 end script post-start script /transloadit/bin/notify.sh 'API2 Just started' end script
More on Node.js
examples of chat, key-value store, and full blown http servers. Basically
parallel/evented processing. You don't? Well if you've ever used
setTimeout(), you'll soon get the hang of it ; )