History: the Ruby-to-Go port

Facts began as a Go port of Puppet Facter . The port — proposed, implemented, verified, and then deliberately departed from — took place between 2026-06-07 and 2026-06-12. This file is the surviving summary of that project (see About this repository’s history ).

Method

The port was test-driven against the Ruby implementation, which stayed in the tree until completion:

• TDD slices. One Ruby behavior at a time: read the Ruby spec, write one failing Go test through the public API or CLI, write the minimal Go code to pass, verify, and record the slice in an append-only migration log (docs/MIGRATION.md, ~9,500 lines by the end — some 685 dated slice entries between 2026-06-07 and 2026-06-09).
• Parity-ledger discipline. A generator (tools/parity-ledger) bucketed every *_spec.rb file under the Ruby spec/ and spec_integration/ trees as in-scope, out-of-scope (with an explicit exclusion rule), or unclassified, and machine-verified that every in-scope entry’s coverage reference named real func Test... declarations. Unclassified files and unwaived blanket coverage failed the check.
• Platform scope. Four release targets: Linux, macOS/Darwin, Windows, and FreeBSD. Solaris, AIX, OpenBSD, NetBSD, DragonFly, and generic BSD paths were declared out of scope because no repeatable validation target existed for them.
• Four blocking platform gates. Every release target got a blocking CI gate (Linux and macOS native runners, Windows Server 2022/2025 runners with tools/windows-release-gate.ps1, and a FreeBSD VM job running tools/freebsd-release-gate.sh); a gate failure fails the pipeline. The current release-target matrix has since expanded — see CONTRIBUTING.md .

Final parity-ledger accounting

The frozen ledger (docs/PARITY_LEDGER.md, generated 2026-06-10, never regenerated) closed with:

The two waivers were Ruby implementation machinery with no Go analog (win32ole_spec.rb, WIN32OLE COM internals; class_discoverer_spec.rb, constant-reflection class discovery), each pinned instead by the Go tests covering the equivalent behavior.

Release-readiness milestones

• 2026-06-07 — port begins. TDD slices against the Ruby specs, logged daily in the migration log through 2026-06-09.
• 2026-06-10 — release readiness. The close-go-port-release-readiness-gaps change closed the gaps: hardened parity ledger (the accounting above), make dist/make install and the release workflow, --puppet bounds, and the facter.conf parser decision — a HOCON-library bake-off found that neither maintained Go HOCON library reproduced Ruby Hocon.load on the documented facter.conf surface, so Facts keeps its pinned-subset parser (see FACTER_CONF_COMPATIBILITY.md ).
• 2026-06-10 — all four platform gates green: the first green Windows and FreeBSD gate runs, after CI iterations that caught real product bugs (missing ol/amzn family mapping, Server 2025 WMI fallback, Windows command quoting, CRLF fixture corruption, and more).
• 2026-06-10 — port declared complete; Ruby removed. The remove-ruby-implementation change deleted lib/, spec/, spec_integration/, acceptance/, ext/, facter.gemspec, install.rb, Gemfile, Rakefile, and the Ruby lint configs, with all gates green on the removal commit. The parity ledger was frozen as the final verification record. Packaging dispositions: the gemspec, install.rb, and the ext/ vanagon/ezbake metadata were frozen as historical for the Ruby gem line and deleted with the removal — Go distribution is make dist archives and make install; the Beaker acceptance/ suite was succeeded by the Go binary-level tests/acceptance package. bin/facter briefly lived on as a cutover shim preferring an installed Go binary; ADR-0008 later deleted it outright.
• 2026-06-11/12 — post-port departures (below), concluding with the rename to facts on 2026-06-12.

Post-port departures

With the port complete and the project still unreleased, Facts deliberately narrowed and reshaped the Ruby-compatibility story. Each step is an archived OpenSpec change with an ADR where it changed a contract:

• Idiomatic Go API (introduce-facts-library-api, 2026-06-11, ADR-0001): the ~58 Ruby-shaped package-level exports and all package-global state were replaced by the immutable facts.Engine / Snapshot surface. Ruby compatibility is promised only at the CLI process boundary.
• No Ruby DSL (remove-ruby-custom-fact-dsl, 2026-06-11, ADR-0006): the ~4,900-line regex DSL parser was removed; no .rb fact file is read anywhere. External facts are the whole input contract (see CUSTOM_FACT_MIGRATION.md ).
• No legacy facts (remove-legacy-facts, 2026-06-11, ADR-0007): the ~150 flat Ruby-era aliases (operatingsystem, hostname, processorcount, …) no longer resolve; the structured tree is the only fact surface.
• Not-applicable facts omitted (omit-not-applicable-facts, 2026-06-11): facts whose preconditions don’t hold are absent instead of empty placeholders, converging default output on Ruby Facter’s fact set.
• Default-format parity and depth color (default-format-parity-and-depth-color, 2026-06-12): the default key => value text format became byte-compatible with Ruby Facter 4.10.0’s LegacyFactFormatter, plus a Facts-only depth-colorized terminal mode.
• Rename to facts (rename-binary-to-facts, 2026-06-12, ADR-0008): the binary, man page, dist artifacts, and diagnostics token all became facts; no facter alias ships. Facter-named inputs remain as the compat tier under the facts-native ones.
• OpenBSD and NetBSD support (add-openbsd-netbsd-support, 2026-06-17): the supported release-target matrix expanded from the original four port-completion targets to include OpenBSD and NetBSD, with VM release gates and schema-backed supported-fact documentation.

The migration log’s append-only discipline ended with the log itself: future behavior changes are recorded in CHANGELOG.md entries and OpenSpec change records under openspec/.

Architecture decisions

The full decisions live in docs/adr/ ; one line each:

• ADR-0001 — One idiomatic Go API; the CLI process boundary is the only Ruby-compatibility boundary (partially superseded by ADR-0006).
• ADR-0002 — The canonical dynamic tree is the only fact model; typing is a view (facts.As[T]), never an independent resolver.
• ADR-0003 — Library engines are hermetic by default; reading host config, fact directories, and caches is explicit opt-in.
• ADR-0004 — The project is “facts”, the binary stays “facter” (superseded by ADR-0008).
• ADR-0005 — Immutable Engine, explicit Discover → immutable Snapshot; no memoizing fact state in the engine.
• ADR-0006 — No Ruby custom-fact DSL; external facts are the whole input contract.
• ADR-0007 — No legacy facts; the structured tree is the only fact surface.
• ADR-0008 — The binary and identity are facts; no facter alias; facts-native input names first, facter-named reads as the compat tier.

About this repository’s history

This repository started as a fork of puppetlabs/facter carrying its full upstream git history (2,340 commits by 84 contributors, dating to 2019). On 2026-06-12 the history was deliberately flattened to a single initial commit: the inherited record overwhelmingly described another product and misrepresented this project’s activity and authorship. The detailed porting-era records (the port tracker, the 9,471-line migration log, the frozen parity ledger, the Ruby internals reference, and the inherited Ruby Facter 4.0.x release notes) were summarized into this file before their removal and are not recoverable from this repository. The Ruby implementation and its complete history remain available in upstream puppetlabs/facter ; attribution is carried by NOTICE , which does not depend on git history.

What lives in HEAD today: CONTEXT.md (the project language), docs/adr/ (the decisions), CONTRIBUTING.md (how to work on Facts, including the still-live TDD rules and release gates that originated in the port tracker), FACTER_CONF_COMPATIBILITY.md and CUSTOM_FACT_MIGRATION.md (the operator-facing compatibility contracts), and man/man8/facts.8 (the CLI manual).