Heroku /tmp folder deletion

Question

From Heroku's information page on the read-only file system

"There are two directories that are writeable: ./tmp and ./log (under your application root). If you wish to drop a file temporarily for the duration of the request, you can write to a filename like #{RAILS_ROOT}/tmp/myfile_#{Process.pid}. There is no guarantee that this file will be there on subsequent requests (although it might be), so this should not be used for any kind of permanent storage."

Does anyone know how often files are deleted from the /tmp folder in Heroku?

"there is no guarantee". e.g. you shouldn't be trying to gamble on how long the file will still be there. — Marc B, Jun 25 '13 at 05:03
@MarcB Sure, I understand that. I'm just curious about the timescale (seconds/minutes/hours/days?) Maybe I need the files 30 seconds after they're put in the `/tmp` folder — Mika H., Jun 25 '13 at 05:06

score 8 · Accepted Answer · answered Jun 25 '13 at 06:53

8

heroku never explicitely removes files from your tmp folder.
However it is not shared between instances of your application (your dynos).

This means you can assume the tmp folder to be emptied every time you deploy your application.
As you should always be able to deploy, you need, for your own sake, to architect your app with that in mind and not rely on the tmp folder to keep files longer than the user's HTTP request.

answered Jun 25 '13 at 06:53

Damien MATHIEU

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So, won't the tmp folder overfill if the user keeps putting new stuff in it and never redeploys the application? – Mika H. Jun 25 '13 at 14:28
You have 620Gb of data in the /tmp folder at the moment - http://stackoverflow.com/questions/12099378/harddisk-quota-cedar-stack-heroku/16938926 So you should have the time to see it coming. But basically, yes. – Damien MATHIEU Jun 25 '13 at 14:58
so where to save files that are needed by the application? – max bugaenko Oct 05 '14 at 07:44
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In a file storage service, like Amazon S3. – Damien MATHIEU Oct 06 '14 at 07:13

Heroku /tmp folder deletion

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