Documentation

Overview

    Package propagation contains OpenTelemetry context propagators.

    This package is currently in a pre-GA phase. Backwards incompatible changes may be introduced in subsequent minor version releases as we work to track the evolving OpenTelemetry specification and user feedback.

    OpenTelemetry propagators are used to extract and inject context data from and into messages exchanged by applications. The propagator supported by this package is the W3C Trace Context encoding (https://www.w3.org/TR/trace-context/), and W3C Baggage (https://w3c.github.io/baggage/).

    Index

    Examples

    Constants

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    Variables

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    Functions

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    Types

    type Baggage

    type Baggage struct{}

      Baggage is a propagator that supports the W3C Baggage format.

      This propagates user-defined baggage associated with a trace. The complete specification is defined at https://w3c.github.io/baggage/.

      func (Baggage) Extract

      func (b Baggage) Extract(parent context.Context, carrier TextMapCarrier) context.Context

        Extract returns a copy of parent with the baggage from the carrier added.

        func (Baggage) Fields

        func (b Baggage) Fields() []string

          Fields returns the keys who's values are set with Inject.

          func (Baggage) Inject

          func (b Baggage) Inject(ctx context.Context, carrier TextMapCarrier)

            Inject sets baggage key-values from ctx into the carrier.

            type HeaderCarrier

            type HeaderCarrier http.Header

              HeaderCarrier adapts http.Header to satisfy the TextMapCarrier interface.

              func (HeaderCarrier) Get

              func (hc HeaderCarrier) Get(key string) string

                Get returns the value associated with the passed key.

                func (HeaderCarrier) Keys

                func (hc HeaderCarrier) Keys() []string

                  Keys lists the keys stored in this carrier.

                  func (HeaderCarrier) Set

                  func (hc HeaderCarrier) Set(key string, value string)

                    Set stores the key-value pair.

                    type TextMapCarrier

                    type TextMapCarrier interface {
                    	// Get returns the value associated with the passed key.
                    	Get(key string) string
                    	// Set stores the key-value pair.
                    	Set(key string, value string)
                    	// Keys lists the keys stored in this carrier.
                    	Keys() []string
                    }

                      TextMapCarrier is the storage medium used by a TextMapPropagator.

                      type TextMapPropagator

                      type TextMapPropagator interface {
                      	// Inject set cross-cutting concerns from the Context into the carrier.
                      	Inject(ctx context.Context, carrier TextMapCarrier)
                      	// Extract reads cross-cutting concerns from the carrier into a Context.
                      	Extract(ctx context.Context, carrier TextMapCarrier) context.Context
                      	// Fields returns the keys who's values are set with Inject.
                      	Fields() []string
                      }

                        TextMapPropagator propagates cross-cutting concerns as key-value text pairs within a carrier that travels in-band across process boundaries.

                        func NewCompositeTextMapPropagator

                        func NewCompositeTextMapPropagator(p ...TextMapPropagator) TextMapPropagator

                          NewCompositeTextMapPropagator returns a unified TextMapPropagator from the group of passed TextMapPropagator. This allows different cross-cutting concerns to be propagates in a unified manner.

                          The returned TextMapPropagator will inject and extract cross-cutting concerns in the order the TextMapPropagators were provided. Additionally, the Fields method will return a de-duplicated slice of the keys that are set with the Inject method.

                          type TraceContext

                          type TraceContext struct{}

                            TraceContext is a propagator that supports the W3C Trace Context format (https://www.w3.org/TR/trace-context/)

                            This propagator will propagate the traceparent and tracestate headers to guarantee traces are not broken. It is up to the users of this propagator to choose if they want to participate in a trace by modifying the traceparent header and relevant parts of the tracestate header containing their proprietary information.

                            Example
                            Output:
                            
                            

                            func (TraceContext) Extract

                            func (tc TraceContext) Extract(ctx context.Context, carrier TextMapCarrier) context.Context

                              Extract reads tracecontext from the carrier into a returned Context.

                              The returned Context will be a copy of ctx and contain the extracted tracecontext as the remote SpanContext. If the extracted tracecontext is invalid, the passed ctx will be returned directly instead.

                              func (TraceContext) Fields

                              func (tc TraceContext) Fields() []string

                                Fields returns the keys who's values are set with Inject.

                                func (TraceContext) Inject

                                func (tc TraceContext) Inject(ctx context.Context, carrier TextMapCarrier)

                                  Inject set tracecontext from the Context into the carrier.