otel

README

OpenTelemetry-Go

OpenTelemetry-Go is the Go implementation of OpenTelemetry. It provides a set of APIs to directly measure performance and behavior of your software and send this data to observability platforms.

Project Status

Signal	Status	Project
Traces	Stable	N/A
Metrics	Alpha	N/A
Logs	Frozen [1]	N/A

• [1]: The Logs signal development is halted for this project while we develop both Traces and Metrics. No Logs Pull Requests are currently being accepted.

Progress and status specific to this repository is tracked in our local project boards and milestones.

Project versioning information and stability guarantees can be found in the versioning documentation.

Compatibility

OpenTelemetry-Go attempts to track the current supported versions of the Go language. The release schedule after a new minor version of go is as follows:

• The first release or one month, which ever is sooner, will add build steps for the new go version.
• The first release after three months will remove support for the oldest go version.

This project is tested on the following systems.

OS	Go Version	Architecture
Ubuntu	1.18	amd64
Ubuntu	1.17	amd64
Ubuntu	1.16	amd64
Ubuntu	1.18	386
Ubuntu	1.17	386
Ubuntu	1.16	386
MacOS	1.18	amd64
MacOS	1.17	amd64
MacOS	1.16	amd64
Windows	1.18	amd64
Windows	1.17	amd64
Windows	1.16	amd64
Windows	1.18	386
Windows	1.17	386
Windows	1.16	386

While this project should work for other systems, no compatibility guarantees are made for those systems currently.

Go 1.18 was added in March of 2022. Go 1.16 will be removed around June 2022.

Getting Started

You can find a getting started guide on opentelemetry.io.

OpenTelemetry's goal is to provide a single set of APIs to capture distributed traces and metrics from your application and send them to an observability platform. This project allows you to do just that for applications written in Go. There are two steps to this process: instrument your application, and configure an exporter.

Instrumentation

To start capturing distributed traces and metric events from your application it first needs to be instrumented. The easiest way to do this is by using an instrumentation library for your code. Be sure to check out the officially supported instrumentation libraries.

If you need to extend the telemetry an instrumentation library provides or want to build your own instrumentation for your application directly you will need to use the Go otel package. The included examples are a good way to see some practical uses of this process.

Export

Now that your application is instrumented to collect telemetry, it needs an export pipeline to send that telemetry to an observability platform.

All officially supported exporters for the OpenTelemetry project are contained in the exporters directory.

Exporter	Metrics	Traces
Jaeger		✓
OTLP	✓	✓
Prometheus	✓
stdout	✓	✓
Zipkin		✓

Contributing

See the contributing documentation.

Documentation

Overview

Package otel provides global access to the OpenTelemetry API. The subpackages of the otel package provide an implementation of the OpenTelemetry API.

The provided API is used to instrument code and measure data about that code's performance and operation. The measured data, by default, is not processed or transmitted anywhere. An implementation of the OpenTelemetry SDK, like the default SDK implementation (go.opentelemetry.io/otel/sdk), and associated exporters are used to process and transport this data.

To read the getting started guide, see https://opentelemetry.io/docs/go/getting-started/.

To read more about tracing, see go.opentelemetry.io/otel/trace.

To read more about metrics, see go.opentelemetry.io/otel/metric.

To read more about propagation, see go.opentelemetry.io/otel/propagation and go.opentelemetry.io/otel/baggage.

Index

• func GetTextMapPropagator() propagation.TextMapPropagator
• func GetTracerProvider() trace.TracerProvider
• func Handle(err error)
• func SetErrorHandler(h ErrorHandler)
• func SetLogger(logger logr.Logger)
• func SetTextMapPropagator(propagator propagation.TextMapPropagator)
• func SetTracerProvider(tp trace.TracerProvider)
• func Tracer(name string, opts ...trace.TracerOption) trace.Tracer
• func Version() string
• type ErrorHandler
  • func GetErrorHandler() ErrorHandler
• type ErrorHandlerFunc
  • func (f ErrorHandlerFunc) Handle(err error)

Examples

• SetLogger

Functions

func GetTextMapPropagator

func GetTextMapPropagator() propagation.TextMapPropagator

GetTextMapPropagator returns the global TextMapPropagator. If none has been set, a No-Op TextMapPropagator is returned.

func GetTracerProvider

func GetTracerProvider() trace.TracerProvider

GetTracerProvider returns the registered global trace provider. If none is registered then an instance of NoopTracerProvider is returned.

Use the trace provider to create a named tracer. E.g.

tracer := otel.GetTracerProvider().Tracer("example.com/foo")

or

tracer := otel.Tracer("example.com/foo")

func Handle

func Handle(err error)

Handle is a convenience function for ErrorHandler().Handle(err).

func SetErrorHandler

func SetErrorHandler(h ErrorHandler)

SetErrorHandler sets the global ErrorHandler to h.

The first time this is called all ErrorHandler previously returned from GetErrorHandler will send errors to h instead of the default logging ErrorHandler. Subsequent calls will set the global ErrorHandler, but not delegate errors to h.

func SetLogger

func SetLogger(logger logr.Logger)

SetLogger configures the logger used internally to opentelemetry.

Example

package main

import (
	"log"
	"os"

	"github.com/go-logr/stdr"
	"go.opentelemetry.io/otel"
)

func main() {
	logger := stdr.New(log.New(os.Stdout, "", log.LstdFlags|log.Lshortfile))
	otel.SetLogger(logger)
}

func SetTextMapPropagator

func SetTextMapPropagator(propagator propagation.TextMapPropagator)

SetTextMapPropagator sets propagator as the global TextMapPropagator.

func SetTracerProvider

func SetTracerProvider(tp trace.TracerProvider)

SetTracerProvider registers `tp` as the global trace provider.

func Tracer

func Tracer(name string, opts ...trace.TracerOption) trace.Tracer

Tracer creates a named tracer that implements Tracer interface. If the name is an empty string then provider uses default name.

This is short for GetTracerProvider().Tracer(name, opts...)

func Version

func Version() string

Version is the current release version of OpenTelemetry in use.

Types

type ErrorHandler

type ErrorHandler interface {

	// Handle handles any error deemed irremediable by an OpenTelemetry
	// component.
	Handle(error)
}

ErrorHandler handles irremediable events.

func GetErrorHandler

func GetErrorHandler() ErrorHandler

GetErrorHandler returns the global ErrorHandler instance.

The default ErrorHandler instance returned will log all errors to STDERR until an override ErrorHandler is set with SetErrorHandler. All ErrorHandler returned prior to this will automatically forward errors to the set instance instead of logging.

Subsequent calls to SetErrorHandler after the first will not forward errors to the new ErrorHandler for prior returned instances.

type ErrorHandlerFunc

type ErrorHandlerFunc func(error)

ErrorHandlerFunc is a convenience adapter to allow the use of a function as an ErrorHandler.

func (ErrorHandlerFunc) Handle

func (f ErrorHandlerFunc) Handle(err error)

Handle handles the irremediable error by calling the ErrorHandlerFunc itself.