Print version information when entering shell

[sagikazarmark]

One thing I like doing is print version information when entering the shell of a new/different project. It tells me what tools I get for the project.

However, writing the version script over and over again results in a lot of duplications.

I propose adding a module that prints version information for already supported tools (eg. languages) and allows users to opt-in for displaying version information when entering a devshell.

Here is what I cooked up:

{ config, lib, ... }:

let
  cfg = config.versions;
in
{
  options.versions = {
    enable = lib.mkEnableOption "Print versions when entering a shell";

    exec = lib.mkOption {
      type = lib.types.lines;
      description = "Bash code to execute to print version information.";
      default = "";
    };
  };

  config = lib.mkIf cfg.enable {
    scripts = {
      versions.exec = cfg.exec;
    };

    enterShell = ''
      versions
    '';
  };
}

In case of Go, the integration would look like this:

  config = lib.mkIf cfg.enable {
    # ...
    versions.exec = "${cfg.package}/bin/go version";
  };

Would you be interested in adding such a module?

[thenonameguy]

'devenv info' already lists the package names, which contain the version strings already, without needing to execute binaries.

[sagikazarmark]

Hm, interesting. Unfortunately, it's not available when using flakes (but I'm guessing that's an easy fix). :/

Also, not all packages may be important. For example, when I'm working on a Go/Kubernetes project, I'm mostly interested in those tools, but not the version of curl or jq being used.

[sagikazarmark]

Any ideas how to expose config.info in flakes?

[thenonameguy]

You don't necessarily need to do that, you can just solve it within the devenv NixOS module itself, with something like this:

  enterShell =
    "${lib.concatMapStringsSep "\n" (pkg: ''
      echo "${pkg.pname}: ${if pkg ? "version" then pkg.version else "unknown"}"
    '') (builtins.filter (pkg: pkg ? "pname" && builtins.elem pkg.pname ["terraform" "ngrok"]) config.packages)}";

Produces:

terraform: 1.4.5
ngrok: 3.1.1

[sagikazarmark]

Thanks @thenonameguy

Looking at devenv info though, I think it would be worth exposing in the flake module.

[domenkozar]

It should be available at devShells.default.config.info.

[sagikazarmark]

@domenkozar thanks!

I tried that, but similarly to #711, it doesn't seem to work.

[domenkozar]

Today I got an idea how we could support flakes in a better way.

Will create a prototype in a few days.

[sagikazarmark]

Sounds good! Happy to test-drive it once you have something cooked up.