Our image upload pipeline has gotten a bit too long and no longer fits in the Heroku’s 30-second limit. We generate several image versions and would like to get a couple of sizes first and the larger processors to be delayed. I’ve looked at a few solutions, first.
- This article describes how to delay all processors, but stores the original file for all versions, first. Other than being wasteful it has a real problem for the Cloudfront cache – if some large image were to be cached before the delayed job can resize it, we’d get an image of a wrong size for 24 hours.
- The carrierwave_backgrounder gem is a better candidate. Unfortunately it relies on a local store and doesn’t work in a distributed environment. I think it shouldn’t be too hard to fetch the original image and then invoke the processors, but I wasn’t ready for a day-long project and it doesn’t quite do what I want – process some versions in the background.
So, here’s a slightly hacky solution to delay-processing of select CarrierWave image versions.
Let’s make all processing conditional upon :is_processing_delayed? and :is_processing_immediate?. You see where this is going.
By default processing is immediate, there’s nothing to do. Add the following to the model that is holding the uploader.
Then delay the method normally in the model’s
self.delay.recreate_delayed_versions! – that’s it.
It almost looks too simple. Improvements? Suggestions?