No permanent filesystem for Heroku?

Question

The app I am currently hosting on Heroku allows users to submit photos. Initially, I was thinking about storing those photos on the filesystem, as storing them in the database is apparently bad practice.

However, it seems there is no permanent filesystem on Heroku, only an ephemeral one. Is this true and, if so, what are my options with regards to storing photos and other files?

Answer 1

It is true. Heroku allows you to create cloud apps, but those cloud apps are not "permanent" - they are instances (or "slugs") that can be replicated multiple times on Amazon's EC2 (that's why scaling is so easy with Heroku). If you were to push a new version of your app, then the slug will be recompiled, and any files you had saved to the filesystem in the previous instance would be lost.

Your best bet (whether on Heroku or otherwise) is to save user submitted photos to a CDN. Since you are on Heroku, and Heroku uses AWS, I'd recommend Amazon S3, with optionally enabling CloudFront.

This is beneficial not only because it gets around Heroku's ephemeral "limitation", but also because a CDN is much faster, and will provide a better service for your webapp and experience for your users.

Answer 2

Depending on the technology you're using, your best bet is likely to stream the uploads to S3 (Amazon's storage service). You can interact with S3 with a client library to make it simple to post and retrieve the files. Boto is an example client library for Python - they exist for all popular languages.

Another thing to keep in mind is that Heroku file systems are not shared either. This means you'll have to be putting the file to S3 with the same application as the one handling the upload (instead of say, a worker process). If you can, try to load the upload into memory, never write it to disk and post directly to S3. This will increase the speed of your uploads.

Because Heroku is hosted on AWS, the streams to S3 happen at a very high speed. Keep that in mind when you're developing locally.