Comment by rgoulter | Hacker News Reader

Comment by rgoulter | Hacker News Reader

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> Is it a complete replacement for Docker?

Docker mainly does two things: there's Docker images as a way of sharing some container-image, and the container runtime to allow running those images for tasks or services in isolated/fresh ways.

Docker images make it easy to distribute software which runs the same everywhere.

Nix is a package manager which tackles that problem, but without using container images: Nix is for distributing software so it has the same behaviour everywhere.

Nix users are often very enthusiastic about Nix because it also enables all sorts of neat developer experiences. e.g. Nix is great for setting up development environments.

In terms of Nix-vs-Docker, Nix is also capable of building Docker/OCI images. So, you could use Nix instead of writing a Dockerfile.

Does it make sense to use nix during the image build process to precisely define dependencies I want to have in the resulting container? Or perhaps in other words, can I use nix and docker together, to have a precisely defined environment I can share with others devs as a result?

> Does it make sense to use nix during the image build process to precisely define dependencies I want to have in the resulting container?

Using a dockerfile with a step like "RUN nix ..."? You can, but it strikes me as a cumbersome way of doing things. Mitchell H describes this way of doing things here: https://mitchellh.com/writing/nix-with-dockerfiles

Whereas, I'd reckon the more idiomatic thing to do is to build the Docker image with Nix code. -- You're going to get a precisely defined environment to share across workstation/CI/etc. Some example Nix code for building Docker images is here https://github.com/NixOS/nixpkgs/blob/master/pkgs/build-supp...

Thanks for the links, that is very useful! It seems like I was thinking about this process the other way around.

yes. nix builds linux filesystem with all dependencies and puts it into oci image.

so locally i use process-compose to avoiding waiting docker builds.

Hm, I skimmed the github page for process-compose and I don't understand how it is different from building the container image directly with nix.

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