emacs-direnv VS devenv

env-commander-mode is a simple mode which allows any shell commands that Emacs invokes to run one or more commands beforehand to initialize the shell environment. There are many Emacs packages which can configure process environments, for example, direnv, but they lack the ability to go a step further and define shell functions and aliases, which is often required by "virtual environment" tools. For those who prefer interacting with shell commands via shell-command rather than shell, eshell, or term, env-commander-mode is here to assist.

I'm using nix to manage python dependencies (see excerpt of flake.nix below) but this means those python dependencies are in a /nix directory, so when lsp tries to figure out project root for them, it thinks they have nothing to do with my own project. Also I'm using emacs-direnv to transparently switch into nix environments (.envrc + use flake), so direnv (correctly) unloads my LSP executable (configured in flake.nix), so even if they should be considered totally separate projects LSP-mode doesn't know how to start up the server.

I've had a good experience with direnv[1] and emacs-direnv[2].

Direnv can automatically load an environment when you enter a directory, so it automatically "opens" virtualenvs/nix shells/etc. The Emacs direnv mode ensures that each buffer sees the direnv mode for its project directory.

I've found this to be a great compromise between automatic behavior on the one hand and transparency + control on the other—I get the right environment loaded automatically very consistently and, if something goes wrong, I can open a shell and poke around to see what's going on (is my nix shell messed up? is the right tool not loaded via direnv? etc). The only time I need to do anything manually is if I make a change to the environment and need to update Emacs about it, in which case I just run M-x direnv-update-environment.

Once I got this set up, I can just rely on executable-find to check for (and find) exactly the right tool on a per-project basis—no more worrying about global or seeing the wrong version of a tool. This also made it easy to do stuff like only run formatting if the corresponding tool is available: I add hooks to various programming language modes that only turn on lsp/formatting/etc if executable-find sees the corresponding executable.

Compared to the hassle I've had to go through helping my colleagues debug VSCode not seeing the right conda environment, virtualenv or the right version of various tools, Emacs + direnv has been a far nicer and more consistent experience.

[1]: https://direnv.net/

[2]: https://github.com/wbolster/emacs-direnv

Alternatively from what /u/hantva said, you can try using direnv and its integration with Emacs. This has a benefit of scaling better if you have more than one such project as each set of env vars is separate.

I'm using lorri and emacs-direnv together, works perfectly fine for me.

Thanks, I'll check this out if I can't get my ideal setup to work. Presume you meant this: https://github.com/wbolster/emacs-direnv ?

I first install direnv which allows me to have a different environment per directory, or in my case, a project. And there is a project that connects Emacs to this. https://github.com/wbolster/emacs-direnv

I use this to source .envrc files into my emacs environment: https://github.com/wbolster/emacs-direnv

almost. to integrate with a shell, you would indeed hook it onto the shell's prompt function. to integrate it with Emacs, you would use https://github.com/wbolster/emacs-direnv , so Emacs sees the project specific process environment too. the isolation is primarily achieved by setting up a custom PATH, PYTHON_PATH and similar vars

Sounds like nix using devenv[1] also would solve this problem.

https://devenv.sh/

It works on MacOS/Windows, unlike systemd. Therefore it's well suited for development environment setups for polyglot teams.

https://devenv.sh/ is one example that uses it to do just that.

I gave devenv multiple tries, and I am sorry to say there are multiple annoying issues that forced me to give up every time.

Some of these 200+ issues are unsolved for a fairly long time.

https://github.com/cachix/devenv/issues

Software developers often want to customize:

1. their home environments: for packages (some reach for brew on MacOS) and configurations (dotfiles, and some reach for stow).

2. their development shells: for build dependencies (compilers, SDKs, libraries), tools (LSP, linters, formatters, debuggers), and services (runtime, database). Some reach for devcontainers here.

3. or even their operating systems: for development, for CI, for deployment, or for personal use.

Nix provision all of the above in the same language, with Nixpkgs, NixOS, home-manager, and devShells such as https://devenv.sh/. What's more, Nix is (https://nixos.org/):

- reproducible: what works on your dev machine also works in CI in prod,

- declarative: you version control and review your configurations and infrastructure as code, at a reasonable level of abstraction,

- reliable: all changes are atomic with easy roll back.

https://devenv.sh/ and nix in general are great for setting up dev environments.

> but worried that the development is not moving forward

There is an open v1.0 PR: https://github.com/cachix/devenv/pull/1005

2) A way to run services apps depend on (databases, job runners, cache etc).

I am going to suggest one of the Nix based tools that do those things:

  - https://devenv.sh/ (I use this at work)

Yup, I haven’t tried it but there is https://devenv.sh which is built on top of nix and makes it simple.

Although Guix reads better than Nix (after all, it's Lisp), I found the support and resources available for learning severely lacking.

Plus, you have to jump through hoops to install non-free software, which goes against the ethos of Guix anyway.

IMHO, Nix is clearly "the winner" here and we'll see more and more adoption as it improves. Lots of folks are doing exciting work (see https://determinate.systems/, https://devenv.sh/, https://flakehub.com/). And the scale and organization around nixpkgs is damn impressive.

I don't think you can ever get Nix as simple as PNPM, simply because native libraries are sometimes annoying, need to be configured at build time to a greater degree and because the problem space it attacks is so much larger than PNPM, which only deals with the JS/Node.js ecosystem.

However, I do think that there exist reasonable levels of abstraction that sacrifice some expressive power for simplicity and such systems could maybe expose a PNPM-like CLI. One example that comes to mind is devenv.nix [1]. While it doesn't yet have a CLI, its configuration file is YAML and relatively simple. I think there's more to be done in this space and I hope for tools that are easier to grasp in the future.

> Nix package files evaluate down to configuration for the Nix package manager, but I haven’t ever seen a good explanation for the basic essentials underneath all the abstraction. Every guide I’ve learned from and all the package defs I’ve read seem to cargo cult many layers of mysterious config composing config. Without easy to learn essentials it’s difficult to grok the system as a whole.

To me it sounds like the essential that you're referring to is the 'derivation' primitive, which is almost always hidden behind the mkDerivation abstraction from nixpkgs. This [2] blog post is an exploration of what exactly that means.

I'd also love for the documentation situation to be much better, in particular in terms of official, curated resources. But I'm not convinced that you actually need to know the difference between derivation and mkDerivation to make effective use of Nix, because in practice you would always use the latter. That said, mkDerivation and the whole of nixpkgs is essentially a huge DSL (I believe this is what you meant when you said 'config composing config') that you do need to know and is woefully underdocumented.

> I would love to adopt Nix for developer tooling for Notion’s engineers, but today it’s about infinity times easier to work around the limitations mentioned of Docker+Ubuntu+NPM than to work around the limitations of Nix.

One approach I have taken to is to specify the environment in Nix, but then generate Docker devcontainers from it, so most people don't come into contact with Nix if they don't want to.

[1] https://devenv.sh

[2] https://ianthehenry.com/posts/how-to-learn-nix/derivations/