om develop: Nix devShell that automates more and guides the user

[srid]

Motivation

The user git clones some project. What to do next?

Mechanism

Generally speaking, 3 things need to happen:

1. Setup the necessary Nix caches to avoid compiling locally
   • Notably, one might use a private Cachix cache. Suppose the read-only auth token is stored in the Git repo, we want to run both cachix authtoken ... and cachix use ...
2. Run om health, which checks various things including that cachix cache are in use (we may need om health: check access to private caches #315), and instruct users to fix the problems accordingly (cf. om health: Use markdown for rendering suggestions and such #291)
3. Show "next steps", which varies between projects, but typically involves running direnv allow (or nix develop) as first step, followed by VSCode setup. This can be Markdown we render in the terminal.

Questions

(3) can be part of om show, but the whole 1-2-3 step process may well require a new subcommand?

Roadmap

• om hack: Initialize #319
• om hack: Multi-stage support for direct direnv integration #329
• Refactor: health check cum auto resolution (so combining om health cachix with our cachix-use action)
  • hack: Run only relevant health checks #328
  • Auto resolution of health check failure (esp. for cachix) om hack: Auto cachix use missing cachix caches #330
• Test: Cachix
  • Fix: use staticWhich to locate cachix fix(hack): Make cachix available at compile time #331
• Test: om health
• om hack --direnv for using in .envrc
• General logging/output improvements
  • Avoid nix command dumps
  • Info like cachix up running should still be show. Should we make nix command dump debug level permanently?
• Non-direnv mode: Simply running om hack should either put the user on nix develop shell (sans direnv) or instruct them how to get direnv (if the project requires it)

[srid]

This seems to be the better markdown renderer:

https://github.com/swsnr/mdcat

Takes a bunch of setting up, however:

Result:

Surprisingly, those links are clickable by default - hover over (they get underlined) and click. Not even need to press modifier keys like Cmd.

EDIT: It can also output images, if the right terminal is configured:

[srid]

Cachix configuration is now being piggybacked on om health config, and om hack now tries to "auto resolve" failures, by automatically running cachix use. The authtoken can be passed as env var, thus omnix doesn't have to handle it.

[srid]

https://omnix.page/om/develop.html