run-it

I deployed a NodeJS Express app behind an nginx reverse proxy and wanted to have the node process supervised so it would automatically be restarted after crashes. I learned about a nifty service supervision suite called runit (inspired by D.J. Bernstein’s daemontools) from working at Cloudkick that would be perfect for the job.

runit has a prgram called runsvdir that monitors a particular directory for subdirectories that represent services. It launches a runsv process for every subdirectory and runsv executes a run script that you create to execute your service. In the Debian runit package, runsvdir watches /etc/service though you should create your service directory under /etc/sv and symlink it into /etc/service so you can test your run scripts.

The catch was, I wanted to run node with an unprivileged user and have the service directory in my home directory so I didn’t have to bother with sudoing. This is possible by having another runsvdir process monitor /home/mark/service. Here’s how I set it up:

/etc/sv/
|-- runsvdir-mark/
      |-- log/
      |    |-- main/
      |    `-- run*
      `-- run*  

/etc/service/
`-- runsvdir-mark@ -> /etc/sv/runsvdir-mark/

/etc/sv/runsvdir-mark/run:  
#!/bin/sh
exec 2>&1
exec chpst -u mark runsvdir /home/mark/service/

/etc/sv/runsvdir-mark/log/run:
#!/bin/sh
exec chpst svlogd -tt ./main/

.

With that, there’s now a runsvdir process monitoring /home/mark/service. I then created:

/home/mark/service
|-- aubergine-0/
      |-- log/
      |    |-- main/
      |    `-- run*
      `-- run*  

/home/mark/service/aubergine-0/run:
#!/bin/sh
exec 2>&1
exec chpst -e /home/mark/service/aubergine-0/env \
node /home/mark/code/aubergine/aubergine.js

/home/mark/service/aubergine-0/log/run:
#!/bin/sh
exec chpst svlogd -tt ./main/

1 year ago  /  0 notes