hyperhive/nix/rust.nix
atlas feeabe97af docs(rust): the dep-cache comment no longer describes two consumers
Follow-up to my own #3171. That PR gave the deploy path its own cache and
left the paragraph above it saying "package builds and checks reuse this"
— which stopped being true in the same commit that made it false.

Merged into one accurate lead-in. The surviving facts (built once, every
consumer passes the same `cleanSrc`) are still worth stating; the claim
about who consumes it belongs to the two blocks below, which say it
correctly.
2026-08-11 22:29:56 +02:00

95 lines
4.4 KiB
Nix

# Shared crane wiring for the rust workspace: the cargo source
# filter, the once-built dependency artifacts, and the native build
# inputs every rust derivation (packages + checks) consumes.
# Imported per system from flake.nix.
{ pkgs, craneLib }:
let
inherit (pkgs) lib;
in
rec {
# Shared between buildDepsOnly + buildPackage + cargoClippy/cargoTest
# so every derivation in the chain sees the same toolchain shape.
# git: hive-c0re's `lifecycle::tests::setup_proposed_*` shell out to
# `git init` + commit under `cargo test` in the sandbox.
# sqlite: matrix-sdk's `sqlite` feature (`hive-matrix-mcp` workspace
# member) — the matrix-sdk-sqlite + rusqlite stack links against
# system libsqlite3 by default.
# cmake: builds `aws-lc-sys` (BoringSSL) from source — pulled in by
# the `rustls` (aws-lc-rs) crypto provider under the OTLP/reqwest
# stack in `hive-metric`.
nativeBuildInputs = [
pkgs.git
pkgs.sqlite
pkgs.pkg-config
pkgs.cmake
];
# Narrowed source tree the rust derivations consume: everything
# cargo cares about (Cargo.toml/Cargo.lock + *.rs/*.toml), selected
# via `lib.fileset` rather than crane's `cleanCargoSource` filter —
# filesets drop directories that contain no selected files, so
# adding or renaming a non-rust directory (nix modules, docs, …)
# does NOT bust this src hash (an empty dir under a plain source
# filter would). All non-rust runtime assets — branding + the claude
# prompt template + claude-settings.json — live in the separate
# `hyperhive-assets` derivation and are loaded by the binaries at
# runtime from `$HIVE_ASSETS_DIR`. Net effect: only `*.rs` /
# `*.toml` / `Cargo.lock` edits rebuild the rust derivations.
cleanSrc = lib.fileset.toSource {
root = ../.;
fileset = craneLib.fileset.commonCargoSources ../.;
};
# The workspace's dependency tree, built once and cached as its own
# derivation so a workspace-only edit doesn't rebuild deps. Every
# consumer passes the same `cleanSrc`, keeping the input hash
# consistent across the chain.
#
# Two dep caches, one per audience, and the split is not premature:
# crane's `buildDepsOnly` defaults `doCheck = true`, which adds
# `--all-targets` to the check and a `cargo test --no-run`, so the cache
# compiles every dev-dependency and test harness in the tree. The CHECKS
# need exactly that. A DEPLOY never runs a test binary and never links
# one, so on the deploy path that work is compiled and thrown away.
#
# They are separate rather than shared because they were never actually
# shared: CI evaluates against hyperhive's own nixpkgs pin, while a host
# overrides it (security patches cannot wait on a lock bump upstream),
# so the two closures differ and neither substitutes for the other. One
# cache per audience therefore costs nobody a second build — it just
# stops the deploy paying for artifacts only CI consumes.
#
# ⚠️ `buildDepsOnly` builds from `mkDummySrc`, so both hashes key on
# Cargo.toml/Cargo.lock rather than on `.rs` files: a code edit rebuilds
# neither, a dependency or toolchain change rebuilds both.
cargoArtifacts = craneLib.buildDepsOnly {
src = cleanSrc;
# Workspace Cargo.toml is virtual (no `[package].name`), so crane
# can't auto-derive a name. Spell it out explicitly — keeps the
# derivation name stable across crane bumps + silences the
# placeholder warning. Same `pname` for the dep + check
# derivations so they share a clean naming family.
pname = "hyperhive-workspace";
version = "0.1.0";
inherit nativeBuildInputs;
};
# The deploy path's cache: same deps, no test targets. `doCheck = false`
# drops crane's `--all-targets` and its `cargo test --no-run`, so
# dev-dependencies and test harnesses are never compiled here.
#
# Only `packages` consume this. Anything that needs to *run* a test —
# `checks.cargo-test` — or lint one — `checks.clippy --all-targets` —
# takes `cargoArtifacts` above instead, and would rebuild what it needs
# if it were pointed here by mistake.
cargoArtifactsBinOnly = craneLib.buildDepsOnly {
src = cleanSrc;
# Distinct pname so the two are told apart in build logs and store
# paths; a shared name would make the useful question ("which cache
# is this rebuild?") unanswerable at a glance.
pname = "hyperhive-workspace-bin";
version = "0.1.0";
doCheck = false;
inherit nativeBuildInputs;
};
}