Using nixos/nix as a builder in Docker

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1

I’m trying to use nix as a builder in a Dockerfile. Building works really well, but my issue is when I get to running. When I try to run the Docker image, I get exec ./blog: no such file or directory. I’m just really confused as to what’s wrong, since I’m fairly sure this is a Nix specific issue and not a Docker one.

The files can be found here:

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2

Are you trying to build an application via Nix, then run that binary on a different system? For similar reasons why you can’t run precompiled binaries on NixOS, you will not easily take a dynamically-linked binary compiled with Nix and run it on a different system by itself. Try executing file ./blog or ldd ./blog, and you will likely find that the compiled binary refers to dynamic loader and dynamic libraries in /nix/store/...

There are a few possible solutions:

  1. Take the entire closure for this package (not just the executable) elsewhere via nix copy or similar
  2. Compile a completely static binary
  3. Use something like nix-bundle.
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Thank you, I decided I’ll just keep using nix for building and running. Is there any way to shrink the build image though?

4

Are you currently building your Docker image by basing it on NixOS/nix, and then invoking nix-build? If so, you will get a much leaner image using dockerTools. This way, you get an image with only what you asked for (the packages you specify and their dependencies). Not even Bash is included AFAIK.

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