Rename trace-dispatcher → hermod-tracing-{core,api,prometheus} and restructure package split

[jutaro]

Summary

Extracts a new thin package from trace-dispatcher, restructures its internal module layout, renames both packages and their module namespaces as part of the hermod-tracing rebranding, extracts Prometheus support into its own optional package, restores trace-dispatcher as a backward-compatible mirror, and updates all consumers accordingly.

Motivation

Previously all tracing types, combinators, and backends lived inside trace-dispatcher. Any package that only needed to instrument its own code — define LogFormatting/MetaTrace instances and call traceWith — was forced to depend on the full backend stack (EKG, Prometheus, CBOR forwarding, async, YAML config parser, …). The split makes the stable API surface available as a lightweight dependency, and keeps the Prometheus TCP server fully opt-in.

Changes

Package split and module restructuring

A new thin package (hermod-tracing-api) was extracted from trace-dispatcher. It contains only what a package needs to define trace types and emit messages, and is itself split into two sublibraries:

• hermod-tracing-api:internal — Hermod.Tracing.Types (the Trace carrier, TraceControl GADT, LogFormatting/MetaTrace typeclasses, and the full TraceConfig/BackendConfig dependency chain) and Hermod.Tracing.Trace/Trace.Combinators (structural and annotation combinators).
• hermod-tracing-api:public — Hermod.Tracing.API, a single-import front door that wraps the internal combinators with ergonomic signatures (contramapM/contramapMCond take (a -> m b), filterTrace takes (a -> Bool), foldTraceM/foldCondTraceM take (acc -> a -> m acc)) and hides LoggingContext/TraceControl from callers entirely. Annotation combinators (setSeverity, withPrivacy, withNames, …) stay internal to hermod-tracing-core, since they aren't part of the minimal type-definition surface.

Build-depends for hermod-tracing-api is kept deliberately small: no async, bytestring, cborg-json, time, or YAML.

The two original large files (Types.hs at 568 lines, Trace.hs at 389 lines) were further divided along natural seams into 7 focused modules. The dependency graph is a strict DAG with no cycles.

Package and namespace renames

Old name	New name
trace-dispatcher	hermod-tracing-{api,core,prometheus}
Cardano.Logging.*	Hermod.Tracing.*

trace-dispatcher itself has been restored as a backward-compatible mirror of origin/master's copy (wired back into cabal.project, CODEOWNERS, and the Nix ecosystem), so existing pinned consumers keep building unchanged.

New package: hermod-tracing-prometheus

The Prometheus TCP server backend (Exposition, NetworkRun, TCPServer) has been extracted from hermod-tracing-core into a standalone optional package. Deps exclusive to the Prometheus server (hashable, http-date, time-manager, unix-compat) are removed from hermod-tracing-core and moved here.

Identifier and field renames

Old	New
mkCardanoTracer / mkCardanoTracer'	mkHermodTracer / mkHermodTracer'
TraceDispatcherMessage	HermodTracingMessage
setupTraceDispatcher (recon)	setupHermodTracing
TRACE_DISPATCHER_LOGGING_HOSTNAME	HERMOD_TRACING_LOGGING_HOSTNAME
PrometheusM constructor	LabelSetM
presentPrometheusM (internal, EKG)	presentLabelSetM
TraceConfig.tcNodeName	tcApplicationName
ConfigRepresentation.traceOptionNodeName (internal)	traceOptionApplicationName

CounterM's field type changed from Maybe Int to CounterAction (CounterIncrement / CounterAdd) for clarity of intent. contramap was made strict; contramap' and >!$!< were removed. routingTrace and contramapM' were briefly dropped during the public-API simplification pass and routingTrace was restored, since its signature never leaked LoggingContext/TraceControl and there was no reason to remove it; contramapM' stays removed.

Hermod.Tracing.Types.NodeInfo and Hermod.Tracing.Types.NodeStartupInfo were removed from hermod-tracing-core (cardano-node–specific types with no generic utility), and the contra-tracer version bound was loosened from ^>= 0.2.1 to unconstrained.

Configuration format changes

• Hermod.Tracing.ConfigurationParser gained ConfigSource (FromFile/FromStrictBytes/FromLazyBytes/FromJSONObject), replacing the bare FilePath parameter of readConfiguration and related functions — configs can now be ingested from a file, a strict/lazy ByteString, or a pre-parsed Aeson.Object.
• The legacy top-level config format ("TraceOptions"/"TraceOptionForwarder"/"TraceOptionResourceFrequency"/…) has been dropped; only the "HermodTracing"-wrapped and flattened top-level formats are now accepted.
• TraceConfig's tcResourceFrequency/tcLedgerMetricsFrequency (Maybe Int, milliseconds) are replaced by a single generalized tcPeriodicTracers :: Map Text Word64, mapping an arbitrary periodic-tracer identifier to a cardinal number interpreted in an application-specific (potentially per-identifier) timeunit, parsed from/emitted to a "PeriodicTracers" JSON object.
• Added a test that parses the example doc/config.json and checks it against the expected TraceConfig.

hermod-recon-framework updated

• Dependency updated from trace-dispatcher to hermod-tracing-core + hermod-tracing-prometheus.
• All Cardano.Logging.* imports replaced with Hermod.Tracing.*.
• Dead CPP backward-compatibility guards (gated on MIN_VERSION_trace_dispatcher) removed.
• CLI flag renamed: --trace-dispatcher-cfg → --hermod-tracing-cfg.

hermod-trace-resources updated

• Dependency updated from trace-dispatcher to hermod-tracing-core.
• Cardano.Logging import updated to Hermod.Tracing.

Versioning

hermod-tracing-api, hermod-tracing-core, and hermod-tracing-prometheus are bumped to 1.0.0, with CHANGELOGs reframed as initial releases based on trace-dispatcher-2.13.0.

Docs and config cleaned up

• UseTraceDispatcher config key removed everywhere (no longer applicable).
• "Transition Period" section removed from the tracing-core design doc.
• Stale references to trace-dispatcher, iohk-monitoring, and Cardano.Logging updated throughout READMEs, CHANGELOGs, and doc files.
• CODEOWNERS updated to reflect all renamed and new packages.

Compatibility

trace-dispatcher continues to exist (restored as a mirror of origin/master's copy) and exports the same surface, so existing consumers keep building unchanged until they migrate to hermod-tracing-*.