Getting vips to work with Rails on Heroku

Suppose you’re starting a new project using Rails 7 and ActiveStorage to handle image uploads. In that case, one change you will notice is vips is the standard way we manipulate images now, replacing ImageMagick.

This was the first time we’ve used vips, and we spent a bit of time trying to work out why things weren’t working on Heroku. I will show you what we did to get things working.

What is vips?

First of all, you might be wondering what vips is. It is an image processing library, so a suite of tools we can use to change images (resize, change colour, etc.).

From the vips library README:

libvips is a demand-driven, horizontally threaded image processing library. Compared to similar libraries, libvips runs quickly and uses little memory.

The “uses little memory” bit is appealing to us Rails folk running things on web servers.

Getting it running locally

I won’t get into the ActiveStorage part of the setup, but from the Rails side, you will need the image_processing gem installed; in a standard Rails install, the line in the Gemfile will look like;

gem 'image_processing', '~> 1.2'

If you don’t already have vips installed on your computer, you will need it.

On a Mac with homebrew, you can run brew install vips, and everything should be good to go.

On a Linux machine with apt, you can run apt get libvips.

I’m not sure about Windows, but it seems like there are binaries you can get from the vips release section.

Heroku

Getting it running locally is one thing, but we need to host it somewhere if other people want to use our application; for us, that somewhere is almost always Heroku.

Heroku has the notion of buildpacks; these are scripts that run to set up the server for you on each deployment. A Rails project would use the Ruby buildpack, which will install Ruby and many common dependencies that Ruby projects need.

At the time of writing, vips is not seen as a common enough dependency to include in the Ruby buildpack. Hopefully, that is something that can change. There is an open issue discussing this very point; it looks like maybe it will come with the newest Heroku stack, but let’s not hold our breath!

It and other threads talk about a buildpack called heroku-buildpack-vips. Unfortunately, we didn’t have much joy by using this buildpack alone. Some folk use it in combinations with some manual installs.

This is what we did, which appeared to work.

Use the apt buildpack; this buildpack allows you to specify which packages should be installed by Heroku; it uses an Aptfile which you can commit with your code.

In our first attempt, we just installed libvips, so our Aptfile looked like this;

libvips

This appeared to work; we deployed our application, and ActiveStorage could save off images we were then manipulating.

In a since closed thread, there was a discussion about getting vips working on Heroku, and Schneems suggested a longer Aptfile.

libglib2.0-0
libglib2.0-dev
libpoppler-glib8
libheif-dev
libvips-dev
libvips

I don’t know enough about this setup to comment, but I presume the above will cover more use cases.

Is there a better way?

Is there a better way than using the Aptfile? I’d love to use a single buildpack, which seems more self-documenting than a file full of things to install.

If you know of one, please do drop me an email at toby@tosbourn.com.