Otel.API.Propagator.TextMap.Noop (otel v0.2.0)

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No-op TextMap propagator used when no propagator is explicitly configured (spec context/api-propagators.md L322-L325, Status: Stable).

Spec L322-L325 MUST:

"The OpenTelemetry API MUST use no-op propagators unless explicitly configured otherwise."

Registered as the default propagator by Otel.API.Propagator.TextMap.get_propagator/0 — when no propagator is installed via set_propagator/1, this module is returned so that inject/3 and extract/3 always have a working propagator to dispatch to. This matches the shape used by Otel.API.Trace.Tracer.Noop, Otel.API.Metrics.Meter.Noop, and Otel.API.Logs.Logger.Noop.

Invariants (spec L322-L325)

  • inject/3 returns the carrier unchanged — no header is written.
  • extract/3 returns the context unchanged — no value is stored.
  • fields/0 returns [] — no headers are read or written.
  • No state held, no configuration, no logs emitted.

Public API

FunctionRole
inject/3SDK (Noop implementation) — TextMap Inject (no-op)
extract/3SDK (Noop implementation) — TextMap Extract (no-op)
fields/0SDK (Noop implementation) — Fields (empty list)

References

  • OTel Context §Global Propagators: opentelemetry-specification/specification/context/api-propagators.md L308-L346
  • OTel Context §TextMap Propagator: opentelemetry-specification/specification/context/api-propagators.md L114-L203

Summary

Functions

extract(ctx, carrier, getter)

SDK (Noop implementation) — No-op Extract (api-propagators.md L322-L325).

fields()

SDK (Noop implementation) — Fields (api-propagators.md L322-L325).

inject(ctx, carrier, setter)

SDK (Noop implementation) — No-op Inject (api-propagators.md L322-L325).

Functions

extract(ctx, carrier, getter)

@spec extract(
  ctx :: Otel.API.Ctx.t(),
  carrier :: Otel.API.Propagator.TextMap.carrier(),
  getter :: Otel.API.Propagator.TextMap.getter()
) :: Otel.API.Ctx.t()

SDK (Noop implementation) — No-op Extract (api-propagators.md L322-L325).

Returns the context unchanged. The carrier and getter parameters are accepted for behaviour conformance but unused. Naturally satisfies spec L100-L102 "MUST NOT throw on parse failure" and "MUST NOT store a new value".

fields()

@spec fields() :: [String.t()]

SDK (Noop implementation) — Fields (api-propagators.md L322-L325).

Returns [] — the no-op propagator reads and writes no headers.

inject(ctx, carrier, setter)

@spec inject(
  ctx :: Otel.API.Ctx.t(),
  carrier :: Otel.API.Propagator.TextMap.carrier(),
  setter :: Otel.API.Propagator.TextMap.setter()
) :: Otel.API.Propagator.TextMap.carrier()

SDK (Noop implementation) — No-op Inject (api-propagators.md L322-L325).

Returns the carrier unchanged. The ctx and setter parameters are accepted for behaviour conformance but unused.