interface

#OpenTelemetry Propagation API

This package moves trace context and baggage through text-based carriers such as HTTP headers.

#Carrier traits

Injector: write side of an outbound carrier
Extractor: read side of an inbound carrier

Map[String, String] implements both traits. When used through Injector, keys are normalized to lowercase. When used through Extractor, lookups are case-insensitive, which makes the map convenient for HTTP-style headers.

#TextMapPropagator

TextMapPropagator::from_functions(inject, extract, fields): builds a custom propagator from three callbacks
inject_context(context, injector): writes propagation fields into the carrier
extract_with_context(context, extractor): reads from the carrier and returns an updated context
fields(): reports the header names the propagator may touch

#BaggagePropagator

BaggagePropagator::new(): reads and writes the baggage header
inject_context(context, injector): serializes baggage into the carrier
extract_with_context(context, extractor): parses baggage and merges it into the supplied context; extracted entries overwrite existing baggage entries with the same key
into_text_map(): erases the concrete type into TextMapPropagator

Malformed baggage items are ignored. Valid items still survive extraction.

#TraceContextPropagator

TraceContextPropagator::new(): reads and writes traceparent and tracestate
inject_context(context, injector): writes the current valid span context
extract_with_context(context, extractor): validates the headers and, on success, returns a context with a remote span context attached
into_text_map(): erases the concrete type into TextMapPropagator

Invalid headers are ignored and leave the input context unchanged.

#TextMapCompositePropagator

TextMapCompositePropagator::new(propagators): creates a propagator that runs multiple propagators in order
inject_context(context, injector): runs every child propagator
extract_with_context(context, extractor): threads the context through the propagators from left to right
into_text_map(): erases the concrete type into TextMapPropagator

Field names are de-duplicated when fields() is queried on the composite.

Extractor

source

pub(open) trait Extractor {
  fn get(Self, StringView) -> String?
  fn keys(Self) -> Array[String] = _
}

Read side of a text-map carrier used for inbound propagation.

Implement this for HTTP header maps or other text carriers that need incoming trace context and baggage extraction. keys() is optional but lets propagators handle case-insensitive carriers more efficiently. Spec: https://opentelemetry.io/docs/specs/otel/context/api-propagators/#extract

impl Extractor for Map[String, String]

Injector

source

pub(open) trait Injector {
  fn set(Self, String, String) -> Unit
}

Write side of a text-map carrier used for outbound propagation.

Implement this for HTTP header maps or other text carriers that need outgoing trace context and baggage injection. Spec: https://opentelemetry.io/docs/specs/otel/context/api-propagators/#inject

impl Injector for Map[String, String]

BaggagePropagator

source

pub struct BaggagePropagator {
  inner : TextMapPropagator
}

W3C baggage propagator wrapper.

Reads and writes the baggage header. Spec: https://opentelemetry.io/docs/specs/otel/baggage/api/#propagation

BaggagePropagator::extract_with_context

source

fn BaggagePropagator::extract_with_context(self : BaggagePropagator, context : @moonbit-community/opentelemetry/interface/context.Context
Context, extractor : &Extractor) -> @moonbit-community/opentelemetry/interface/context.Context
Context

Extracts baggage from the carrier and returns an updated context. Spec: https://opentelemetry.io/docs/specs/otel/context/api-propagators/#textmap-extract

BaggagePropagator::inject_context

source

fn BaggagePropagator::inject_context(self : BaggagePropagator, context : @moonbit-community/opentelemetry/interface/context.Context
Context, injector : &Injector) -> Unit

Injects baggage from context into the carrier. Spec: https://opentelemetry.io/docs/specs/otel/context/api-propagators/#textmap-inject

BaggagePropagator::into_text_map

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fn BaggagePropagator::into_text_map(self : BaggagePropagator) -> TextMapPropagator

Erases the concrete baggage propagator type into TextMapPropagator. Spec: https://opentelemetry.io/docs/specs/otel/baggage/api/#propagation

BaggagePropagator::new

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fn BaggagePropagator::new() -> BaggagePropagator

Creates a baggage propagator that reads and writes the baggage header.

Extraction is forgiving: malformed entries are ignored and valid entries are merged into the provided context. Spec: https://opentelemetry.io/docs/specs/otel/baggage/api/#propagation

TextMapCompositePropagator

source

pub struct TextMapCompositePropagator {
  inner : TextMapPropagator
}

Composite propagator that applies multiple propagators in sequence.

The default global propagator uses this to combine trace context and baggage. Spec: https://opentelemetry.io/docs/specs/otel/context/api-propagators/#composite-propagator

TextMapCompositePropagator::extract_with_context

source

fn TextMapCompositePropagator::extract_with_context(self : TextMapCompositePropagator, context : @moonbit-community/opentelemetry/interface/context.Context
Context, extractor : &Extractor) -> @moonbit-community/opentelemetry/interface/context.Context
Context

Extracts using every child propagator in order. Spec: https://opentelemetry.io/docs/specs/otel/context/api-propagators/#composite-propagator

TextMapCompositePropagator::inject_context

source

fn TextMapCompositePropagator::inject_context(self : TextMapCompositePropagator, context : @moonbit-community/opentelemetry/interface/context.Context
Context, injector : &Injector) -> Unit

Injects using every child propagator in order. Spec: https://opentelemetry.io/docs/specs/otel/context/api-propagators/#composite-propagator

TextMapCompositePropagator::into_text_map

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fn TextMapCompositePropagator::into_text_map(self : TextMapCompositePropagator) -> TextMapPropagator

Erases the concrete composite propagator type into TextMapPropagator. Spec: https://opentelemetry.io/docs/specs/otel/context/api-propagators/#composite-propagator

TextMapCompositePropagator::new

source

fn TextMapCompositePropagator::new(propagators : ArrayView[TextMapPropagator]) -> TextMapCompositePropagator

Creates a propagator that runs multiple propagators in order.

Injection runs every propagator. Extraction threads the context through the propagators from left to right. Reported fields are de-duplicated. Spec: https://opentelemetry.io/docs/specs/otel/context/api-propagators/#composite-propagator

TextMapPropagator

source

pub struct TextMapPropagator {
  inject_fn : (@moonbit-community/opentelemetry/interface/context.Context
Context, &Injector) -> Unit
  extract_fn : (@moonbit-community/opentelemetry/interface/context.Context
Context, &Extractor) -> @moonbit-community/opentelemetry/interface/context.Context
Context
  fields_fn : () -> Array[String]
}

Erased text-map propagator built from inject/extract callbacks.

Use this as the common type for concrete propagators and custom propagation formats. Spec: https://opentelemetry.io/docs/specs/otel/context/api-propagators/#textmap-propagator

TextMapPropagator::extract_with_context

source

fn TextMapPropagator::extract_with_context(self : TextMapPropagator, context : @moonbit-community/opentelemetry/interface/context.Context
Context, extractor : &Extractor) -> @moonbit-community/opentelemetry/interface/context.Context
Context

Extracts values from the carrier and returns an updated context.

Call this when handling an inbound request, then use the returned context as the parent context for server spans and downstream work. Spec: https://opentelemetry.io/docs/specs/otel/context/api-propagators/#textmap-extract

TextMapPropagator::fields

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fn TextMapPropagator::fields(self : TextMapPropagator) -> Array[String]

Returns the header names this propagator may read or write. Spec: https://opentelemetry.io/docs/specs/otel/context/api-propagators/#fields

TextMapPropagator::from_functions

source

fn TextMapPropagator::from_functions(inject_fn : (@moonbit-community/opentelemetry/interface/context.Context
Context, &Injector) -> Unit, extract_fn : (@moonbit-community/opentelemetry/interface/context.Context
Context, &Extractor) -> @moonbit-community/opentelemetry/interface/context.Context
Context, fields_fn : () -> Array[String]) -> TextMapPropagator

Creates a custom text-map propagator from inject/extract/fields callbacks. Spec: https://opentelemetry.io/docs/specs/otel/context/api-propagators/#textmap-propagator

TextMapPropagator::inject_context

source

fn TextMapPropagator::inject_context(self : TextMapPropagator, context : @moonbit-community/opentelemetry/interface/context.Context
Context, injector : &Injector) -> Unit

Injects values from context into the supplied carrier.

Call this before making an outbound request so downstream services can join the same trace and receive baggage. Spec: https://opentelemetry.io/docs/specs/otel/context/api-propagators/#textmap-inject

TraceContextPropagator

source

pub struct TraceContextPropagator {
  inner : TextMapPropagator
}

W3C trace-context propagator wrapper.

Reads and writes traceparent and tracestate. Spec: https://opentelemetry.io/docs/specs/otel/context/api-propagators/#w3c-trace-context-requirements

TraceContextPropagator::extract_with_context

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fn TraceContextPropagator::extract_with_context(self : TraceContextPropagator, context : @moonbit-community/opentelemetry/interface/context.Context
Context, extractor : &Extractor) -> @moonbit-community/opentelemetry/interface/context.Context
Context

Extracts a remote span context from the carrier when the headers are valid. Spec: https://opentelemetry.io/docs/specs/otel/context/api-propagators/#textmap-extract

TraceContextPropagator::inject_context

source

fn TraceContextPropagator::inject_context(self : TraceContextPropagator, context : @moonbit-community/opentelemetry/interface/context.Context
Context, injector : &Injector) -> Unit

Injects the current span context into the carrier when it is valid. Spec: https://opentelemetry.io/docs/specs/otel/context/api-propagators/#textmap-inject

TraceContextPropagator::into_text_map

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fn TraceContextPropagator::into_text_map(self : TraceContextPropagator) -> TextMapPropagator

Erases the concrete trace-context propagator type into TextMapPropagator. Spec: https://opentelemetry.io/docs/specs/otel/context/api-propagators/#w3c-trace-context-requirements

TraceContextPropagator::new

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fn TraceContextPropagator::new() -> TraceContextPropagator

Creates a trace-context propagator that reads and writes traceparent and tracestate.

Invalid headers are ignored and leave the incoming context unchanged. Spec: https://opentelemetry.io/docs/specs/otel/context/api-propagators/#w3c-trace-context-requirements

Source Files

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#OpenTelemetry Propagation API

#Carrier traits

#TextMapPropagator

#BaggagePropagator

#TraceContextPropagator

#TextMapCompositePropagator

#Extractor

#Injector

#BaggagePropagator

#BaggagePropagator::extract_with_context

#BaggagePropagator::inject_context

#BaggagePropagator::into_text_map

#BaggagePropagator::new

#TextMapCompositePropagator

#TextMapCompositePropagator::extract_with_context

#TextMapCompositePropagator::inject_context

#TextMapCompositePropagator::into_text_map

#TextMapCompositePropagator::new

#TextMapPropagator

#TextMapPropagator::extract_with_context

#TextMapPropagator::fields

#TextMapPropagator::from_functions

#TextMapPropagator::inject_context

#TraceContextPropagator

#TraceContextPropagator::extract_with_context

#TraceContextPropagator::inject_context

#TraceContextPropagator::into_text_map

#TraceContextPropagator::new

Source Files

Extractor

Injector

BaggagePropagator

BaggagePropagator::extract_with_context

BaggagePropagator::inject_context

BaggagePropagator::into_text_map

BaggagePropagator::new

TextMapCompositePropagator

TextMapCompositePropagator::extract_with_context

TextMapCompositePropagator::inject_context

TextMapCompositePropagator::into_text_map

TextMapCompositePropagator::new

TextMapPropagator

TextMapPropagator::extract_with_context

TextMapPropagator::fields

TextMapPropagator::from_functions

TextMapPropagator::inject_context

TraceContextPropagator

TraceContextPropagator::extract_with_context

TraceContextPropagator::inject_context

TraceContextPropagator::into_text_map

TraceContextPropagator::new