Documentation
¶
Overview ¶
Package autoprop provides an OpenTelemetry TextMapPropagator creation function. The OpenTelemetry specification states that the default TextMapPropagator needs to be a no-operation implementation. The opentelemetry-go project adheres to this requirement. However, for systems that perform propagation this default is not ideal. This package provides a TextMapPropagator with useful defaults (a combined TraceContext and Baggage TextMapPropagator), and supports environment overrides using the OTEL_PROPAGATORS environment variable.
Index ¶
Examples ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
func NewTextMapPropagator ¶
func NewTextMapPropagator(props ...propagation.TextMapPropagator) propagation.TextMapPropagator
NewTextMapPropagator returns a new TextMapPropagator composited by props or one defined by the OTEL_PROPAGATORS environment variable. The TextMapPropagator defined by OTEL_PROPAGATORS, if set, will take precedence to the once composited by props.
The propagators supported with the OTEL_PROPAGATORS environment variable by default are: tracecontext, baggage, b3, b3multi, jaeger, xray, ottrace, and none. Each of these values, and their combination, are supported in conformance with the OpenTelemetry specification. See https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/sdk-environment-variables.md#general-sdk-configuration for more information.
The supported environment variable propagators can be extended to include custom 3rd-party TextMapPropagator. See the RegisterTextMapPropagator function for more information.
If OTEL_PROPAGATORS is not defined and props is no provided, the returned TextMapPropagator will be a composite of the TraceContext and Baggage propagators.
Example ¶
package main
import (
"fmt"
"sort"
"go.opentelemetry.io/contrib/propagators/autoprop"
"go.opentelemetry.io/otel"
)
func main() {
// NewTextMapPropagator returns a TraceContext and Baggage propagator by
// default. The response of this function can be directly registered with
// the go.opentelemetry.io/otel package.
otel.SetTextMapPropagator(autoprop.NewTextMapPropagator())
fields := otel.GetTextMapPropagator().Fields()
sort.Strings(fields)
fmt.Println(fields)
}
Output: [baggage traceparent tracestate]
Example (Arguments) ¶
package main
import (
"fmt"
"sort"
"go.opentelemetry.io/contrib/propagators/autoprop"
"go.opentelemetry.io/contrib/propagators/b3"
"go.opentelemetry.io/otel/propagation"
)
func main() {
// NewTextMapPropagator behaves the same as the
// NewCompositeTextMapPropagator function in the
// go.opentelemetry.io/otel/propagation package when TextMapPropagator are
// passed as arguments.
fields := autoprop.NewTextMapPropagator(
propagation.TraceContext{},
propagation.Baggage{},
b3.New(),
).Fields()
sort.Strings(fields)
fmt.Println(fields)
}
Output: [baggage traceparent tracestate x-b3-flags x-b3-sampled x-b3-spanid x-b3-traceid]
Example (Environment) ¶
package main
import (
"fmt"
"os"
"sort"
"go.opentelemetry.io/contrib/propagators/autoprop"
"go.opentelemetry.io/otel/propagation"
)
func main() {
// Propagators set for the OTEL_PROPAGATORS environment variable take
// precedence and will override any arguments passed to
// NewTextMapPropagator.
_ = os.Setenv("OTEL_PROPAGATORS", "b3,baggage")
// Returns only a B3 and Baggage TextMapPropagator (i.e. does not include
// TraceContext).
fields := autoprop.NewTextMapPropagator(propagation.TraceContext{}).Fields()
sort.Strings(fields)
fmt.Println(fields)
}
Output: [baggage x-b3-flags x-b3-sampled x-b3-spanid x-b3-traceid]
func RegisterTextMapPropagator ¶
func RegisterTextMapPropagator(name string, p propagation.TextMapPropagator)
RegisterTextMapPropagator sets the TextMapPropagator p to be used when the OTEL_PROPAGATORS environment variable contains the propagator name. This will panic if name has already been registered or is a default (tracecontext, baggage, b3, b3multi, jaeger, xray, or ottrace).
Example ¶
package main
import (
"fmt"
"os"
"go.opentelemetry.io/contrib/propagators/autoprop"
"go.opentelemetry.io/otel/propagation"
)
type myTextMapPropagator struct{ propagation.TextMapPropagator }
func (myTextMapPropagator) Fields() []string {
return []string{"my-header-val"}
}
func main() {
// To use your own or a 3rd-party exporter via the OTEL_PROPAGATORS
// environment variable, it needs to be registered prior to calling
// NewTextMapPropagator.
autoprop.RegisterTextMapPropagator("custom-prop", myTextMapPropagator{})
_ = os.Setenv("OTEL_PROPAGATORS", "custom-prop")
fmt.Println(autoprop.NewTextMapPropagator().Fields())
}
Output: [my-header-val]
func TextMapPropagator ¶ added in v0.34.0
func TextMapPropagator(names ...string) (propagation.TextMapPropagator, error)
TextMapPropagator returns a TextMapPropagator composed from the passed names of registered TextMapPropagators. Each name must match an already registered TextMapPropagator (see the RegisterTextMapPropagator function for more information) or a default (tracecontext, baggage, b3, b3multi, jaeger, xray, or ottrace).
If "none" is included in the arguments, or no names are provided, the returned TextMapPropagator will be a no-operation implementation.
An error is returned for any un-registered names. The remaining, known, names will be used to compose a TextMapPropagator that is returned with the error.
Types ¶
This section is empty.
Source Files