Hi Marcus, I see loglines in the build that show Nix getting that specific version so it might be connected to using nixpacks. Have you tried seeing if using a Dockerfile and and specifying a certain version of dart works here?

Yeah, I kinda have a weird case for that. Basically, I have a command I need to run that generates the Dockerfile. So, I can't just deploy via Dockerfile directly. I suppose I could use GitHub Actions or something to build the image, then deploy that image to Railway, but that definitely takes a lot of the value out of the service. It's not a blocker or anything, but I find it weird. Is Nixpacks open source? Could I help bump the minimum version?

Nixpacks is open source and you can check out the contributing guidelines if you would like to make your own contributions there: https://github.com/railwayapp/nixpacks?tab=readme-ov-file#contributing

Thank you for your help! I finally got a minute to do some research and found the current version of dart in nix is at 3.5.4 (source document here https://github.com/NixOS/nixpkgs/blob/nixos-24.11/pkgs/development/compilers/dart/sources.nix) so I'm not sure why Railway seems to be set to 3.0.6. Unfortunately I don't couldn't figure out how Nitpicks pulls that value in the amount of time I've been able to dig into it.

That version is over a year old now and it'd be really nice to get support for modern Dart right now I'm stuck compiling a Docker image in Github Actions and using that to deploy to Railway, but I'd really rather not have that be my only option. Thanks!

Why not have Railway build your Dockerfile for you?

I think I tried that and that's when I discovered it always pulls the old version of Dart unless I'm missing something big? Manually building the docker image in Github was a work-around.

If you are using a Dockerfile to build on Railway and it still pulls the old version -- you either aren't using the Dockerfile, or are specifying an old version in the Dockerfile.