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Roadmap

Roughly eight weeks of part-time work, in four milestones. Each milestone is a tagged release with a gate: a concrete check that must pass before the tag.

timeline
    title sdvarlink milestones
    section Core
        v0.1 Core (weeks 1–2) : framing, Conn, Call : streaming iterators : error types, raw calls : unit tests + fuzzing
    section Bindings
        v0.2 Generator (weeks 3–4) : IDL capture + parser : emitter + type mapping : resolve, userdatabase, manager, metrics for v257 and v260
    section Differentiators
        v0.3 fds + fake (weeks 5–6) : SCM_RIGHTS send/receive : fd lifecycle tests : varlinktest, typed handlers, record/replay
    section Launch
        v0.4 Matrix + docs (weeks 7–8) : integration matrix + drift job : Supports() : examples + docs site
        v1.0 : one release cycle without breaking changes

Milestones and gates

Milestone Scope Gate
v0.1 Core Framing, Conn, Call, streaming iterators, error type, raw calls, unit tests and fuzzing. Raw calls to io.systemd.Manager and io.systemd.Resolve work on a v260 host.
v0.2 Generator IDL capture job, parser, emitter, type mapping; generated resolve, userdatabase, manager, metrics for v257 and v260. Generated code compiles for every captured interface and passes golden-file tests.
v0.3 fds and fake SCM_RIGHTS send/receive, fd lifecycle tests, varlinktest with typed handlers and record/replay. An fd-taking method round-trips against real systemd, and open-fd counts stay flat across 10,000 calls.
v0.4 Matrix and docs Integration matrix, drift job, Supports(), examples, pkg.go.dev docs, this site. Green matrix on v257, v258 and v260; a first external user (tether or report2otel) builds on it.
v1.0 API freeze. The API has gone a release cycle without breaking changes.

Gate checklist

  • Generated code compiles for every captured interface (v257, v258, v260: 79 packages).
  • Generator output pinned by golden-file tests.
  • fd round trip and leak tests against the fake (thousands of calls, flat fd count).
  • Integration tests against a real systemd-journald, and varlinkctl as a client of the fake.
  • Supports() on every generated client; 15 runnable examples; documentation site.
  • fd-taking method round-tripped against real systemd (mountfsd) in CI.
  • Green integration matrix on v257, v258 and v260 VMs.
  • First external user builds on it.

Follow-on work

  • Varlink server (done)

    varlink.Server serves interfaces from Go: typed handlers, live and list streams, peer credentials, socket activation and graceful shutdown. Go daemons can now publish io.systemd.Metrics under /run/systemd/report/, the base for report2otel. See Serving Varlink.

  • tether backend

    A tether backend that swaps D-Bus calls for sdvarlink wherever Varlink is available, falling back to D-Bus elsewhere.

Out of scope

These are deliberate non-goals: replacing go-systemd's D-Bus packages, wrapping systemctl semantics, org.varlink.resolver, and TCP/TLS or remote transports. The server serves Unix sockets only, and has no upgrade support yet.

Have a use case that doesn't fit? Open an issue.