LibreOffice headless: debugging session (OMG!)

Logo LibreofficeA couple of years ago I decided to try LibreOffice’s «–convert-to» parameter to generate different formats of a document, instead of using the ancient listen-on-port-8100 service and use an external Python script in order to do the dirty job of conversion. The results of the tests where great: excelent performance, reliable results, avoid the control of port 8100: IM-PRESSIVE! 🙂

Recently an ancient Rails 2.3 app was failing in the generation of PDFs via this 8100 port + Python script stuff 🙁 I could try to figure out which the error was (dive into Python) or migrate to that convert-to simple solution: no doubt!.

I change my scripts for PDF generation, but something nasty was waiting me around the corner 🙁

  • It didn’t work just out of the box.
  • Local development setup was working right.
  • Debugging time! 🙂

First I tried at CLI:

libreoffice --headless --convert-to --outdir /tmp my-test-file.odt

It works!. So problem is not neither with Libreoffice and Ruby version. Trouble is elsewhere. Next I consider my code: perhaps something was interfering and I decided to set a simple «runner» task just to call the system:

# simple-task.tb
`libreoffice --headless --convert-to --outdir /tmp my-test-file.odt`

Nope, seems to fail again 🙁 Then I tried to get the output error. I found an excellent post about: So I changed my task:

# simple-task.tb
output = `libreoffice --headless --convert-to --outdir /tmp my-test-file.odt 2>&1`'DEBUG: ' + output)

The output was a simple: «Error: source file could not be loaded» :/ After so many searches at DuckDuckGo (please avoid Google-vil) I found a tip at Stackoverflow here: Then I tried to reproduce it: yes if the source file (the one to be converted) does not exist then, the same error shows up!. Mmmm, path issue?, naaahh. Seems to be a dead-end, so time for lateral thinking 🙂

The server has some other apps with the same environment (Rails 2.3, Ruby 1.8.7): what if try the same runner task with them?. I found interesting results: some of them worked and some don’t. So the failure had to be with subtle difference somewhere between apps: almost there 🙂

Finally I found the guilty code: a stupid line at «config/environments/production.rb»:

ENV['TMPDIR'] = '/srv/rails/tmp'

That path does not exist in current server, so LibreOffice was unable to generate/find the middle temporary file in order to convert the document. Remove that line and yes!, I have it up and running again 🙂

What do I’ve learned after 2 days debugging session?:

  • I manage the stress better than 2 before 😀
  • Put configuration environment constants elsewhere is a bad habit
  • Debugging is nice: you learn a lot of things, but it so stressful 🙁
  • Going for a walk or so helps a lot in lateral thinking 🙂

Cheers! 🙂

Acerca de Ibon

Me gusta salir a correr, pasear, andar en bici y patinar :) Si no te saludo es que, o no llevo las gafas puestas o que tengo mal día. Pero no te lo tomes a mal: seguro que mañana estoy de mejor humor ;) Me gusta escuchar algunos podcasts sobre divulgación científica: Coffee Break, CienciaES, y algunos otros que divulgan buen karma. Creo en los principios que fundamentan el Software Libre, y me parece una gran herramienta para conseguir una sociedad mas justa.
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