Proposal: mechanism for doing environment setup

[alecthomas]

Hermit currently performs no custom actions on environment activation.

However, it is not uncommon to want to perform additional tasks within an environment before it becomes usable, beyond just installing the package. Some examples of this are creating a .venv for Python, perhaps running rustup to install a Rust toolchain, and so on.

Probably the simplest approach is to allow hooks in bin/hermit.hcl, eg.

// Run once on environment "initialisation", whatever that means? This concept does not exist yet.
on setup {
  run { command = "..." }
}

// Run on every activation? Is that a good idea?
on activate {
  run { command = "..." }
}

[quad]

I'm OK with an on activate; we should make clear in the documentation that potentially happens a lot, so anything here needs to run fast.

What happens in the case of failure? Right now, when a trigger fails, there's not much in the way of logging. At least I find them hard to debug.

[alecthomas]

Yeah I think that is a bug we should fix :(

[fmr]

How do I upvote this? Anyway, I upvote ⬆️ for all it's worth 😄

[damienrj]

on activate makes a lot of sense. I think the speed is less of an issues as long as it is transparent that it is doing something. Alternatively on setup could basically be on first activation which would also be a nice option if users are doing something slowly. HERMIT_ACTIVATED for example could be set.