nordisk/edda

nornir build variants — declarative build "goals" + a Build button

A product like holger ships several distinct binaries/profiles (embedd / mikro / full, plus optional wasm + feature toggles). Instead of remembering the cargo build -p … --bin … --features … incantations, each product declares its valid build variants as data; nornir validates a chosen variant, materializes it into a cargo build, and can present the options + a Build button. PLAN task #19. Lives in src/build/variant.rs ([build] in nornir.toml or .nornir/build-variants.toml).

Design

• BuildVariant — one buildable goal: name, package (→ -p), bin (→ --bin), features (→ --features a,b), no_default_features, profile (Dev = cargo default / no flag, Release/Custom(name) → --profile), target (→ --target), cfg (→ threaded through RUSTFLAGS --cfg).
• BuildVariantSet — the space of valid choices a product offers: offers (the allowed feature universe), exclusive (mutually-exclusive feature groups), required (per---bin required features, mirroring Cargo required-features), and the concrete variants. validate() rejects a feature not in offers, two features from one exclusive group, or a bin missing its required features.
• Materialize — cargo_args() renders argv in a fixed order (build -p --bin --features --no-default-features --profile --target); build() validates then runs cargo in the repo dir.
• Load — from [build]/[[build.variant]] in nornir.toml (inline) or a standalone .nornir/build-variants.toml (BuildVariantSet::discover). The descriptor is serde-serializable + enumerable so a UI can list the variants, their option axes, and validity, with a "Build" action that calls the materialize→build path (the nornir-viz presentation).

Worked example — holger's real products: holger-server (pkg holger-server-cli), holger-agent (pkg holger-agent-cli), holger-mannequin, plus the fat GUI holger-ui (required-features = ["gui"]). Encoded as offers = ["gui","served","testmatrix"], exclusive = [["gui","lean"]], required."holger-ui" = ["gui"].

Guide

nornir build --list-variants        # print each variant → its cargo command line
nornir build --variant server       # validate + materialize + run cargo build
nornir build --variant ui --dry-run # validate + print the argv, build nothing
nornir build --variant full --repo /path/to/holger

Add a variant = add a [[build.variant]] table (or a row to the set) — no code change. Invalid combinations are rejected up front with the reason.

Idiot guide

• "How do I build the GUI / the server / the tiny one?" → nornir build --list-variants shows every buildable target this repo offers; pick one with nornir build --variant <name>.
• "Can I just see the command without building?" → add --dry-run.
• "It refused my variant." → you asked for a feature the product doesn't offer, or two that can't be on together — the error names which.