go-facter

A pure-Go (no cgo) reimplementation of Puppet's Facter system-inventory engine.

go-facter discovers structured facts about the host — operating system, kernel, networking, processors, memory, filesystems, virtualization, uptime, identity and more — and exposes them through a small, stable Go API designed to be bound onto Ruby's Facter interface (Facter.value, Facter[], Facter.add, Facter.to_hash).

It is the engine layer: a sibling go-ruby-facter binds the Ruby Facter API onto it so Puppet manifests and Ruby code running under rbgo can resolve facts. It is a standalone, dependency-free module — it imports only the Go standard library.

c := facter.New()
name, _ := c.Value("os.name")             // -> Facter.value("os.name")
all := c.ToHash()                          // -> Facter.to_hash
c.AddValue("role", "web")                  // -> Facter.add
c.LoadExternalFacts("/etc/facter/facts.d") // external facts

Why it exists

Puppet's Facter is Ruby with C extensions and shells out heavily. To run Puppet manifests and Ruby fact code under a pure-Go embedded Ruby (rbgo) with cgo disabled and a static binary, the fact engine has to be pure Go too. go-facter provides that engine, matching Facter's fact names and schema so it is a drop-in.

• Why a Go engine — the split between engine and Ruby surface.
• Facts & schema — every fact group and its structure.
• Usage & API — the Go API the Ruby layer maps onto, and the CLI.
• Custom & external facts — extending the fact set.
• Roadmap — what is done and what is next.

Guarantees

• Pure Go, zero cgo. Standard library only; cross-compiles everywhere.
• Faithful to Facter's schema. Aggregate structured facts plus flat legacy aliases.
• 100% test coverage including error branches, enforced as a CI gate, green on Linux, macOS and Windows across the six 64-bit Go targets.