[cwp]

The appeal of Docker is that containers give you repeatable deployments. Once you have an image, you can deploy it in a well-defined way. But it punts on the question of how you build the image.

Nix provides repeatable deployments at the package level. The destination environment can be a user's environment, a container, a VM, a cloud instance, an NixOS machine, an HTTP server or whatever.

Once you're using nix, I don't see any point in using Docker. If you're running Mesos or something like that, it might be worthwhile to build containers for deployment, but if all you want is your packages on a server, Nix gives you that out of the box.

[pbowyer]

I wonder what Joyent and/or @bcantrill would say about that? It'd be super-cool to be able to run nix deployments in a Triton (instance|container|whateveritis)!

[cwp]

Yeah, Nix on SmartOS would be awesome. With the right filesystem jiggery, the nix store could be shared across zones. That would make the whole system faster and more efficient. Also, specifying a Manta job via next would be amazing.

I've brought it up a few times with Joyent folk, but they haven't looked at it seriously. I think they're so spooked by Docker that they can't pay attention to anything else.

[kazagistar]

Docker lets you run arbitrary N to M for Hardware to Software ala virtualization, with low enough overhead. Does Nix have a story for this?

[cwp]

I suppose so. Nix allows me to run N services on M machines arbitrarily with no virtualization and no overhead.

My team builds a distributed application. We have nix expressions that define packages for all the parts of the application, and systemd services to run them on NixOS. Using those packages:

  • Our production deployment is defined by some Nix expressions that assign the services to different machines in the cluster. 
  • Our staging deployment is a Nix expression that runs all the services on a single machine. 
  • Our development deployment is a Nix expression that creates an environment where all dependencies are available and the application can be executed by hand.

Nix lets you do what Docker does, but at the package level, with no virtualization.