go2sky

README

GO2Sky

GO2Sky is an instrument SDK library, written in Go, by following Apache SkyWalking tracing and metrics formats.

Installation

$ go get -u github.com/marlonfan/go2sky

The API of this project is still evolving. The use of vendoring tool is recommended.

Quickstart

By completing this quickstart, you will learn how to trace local methods. For more details, please view the example

Configuration

GO2Sky can export traces to Apache SkyWalking OAP server or local logger. In the following example, we configure GO2Sky to export to OAP server, which is listening on oap-skywalking port 11800, and all of the spans from this program will be associated with a service name example.

r, err := reporter.NewGRPCReporter("oap-skywalking:11800")
if err != nil {
   log.Fatalf("new reporter error %v \n", err)
}
defer r.Close()
tracer, err := go2sky.NewTracer("example", go2sky.WithReporter(r))

Create span

To create a span in a trace, we used the Tracer to start a new span. We indicate this as the root span because of passing context.Background(). We must also be sure to end this span, which will be show in End span.

span, ctx, err := tracer.CreateLocalSpan(context.Background())

Create a sub span

A sub span created as the children of root span links to its parent with Context.

subSpan, newCtx, err := tracer.CreateLocalSpan(ctx)

End span

We must end the spans so they becomes available for sending to the backend by a reporter.

subSpan.End()
span.End()

Advanced Concepts

We cover some advanced topics about GO2Sky.

Context propagation

Trace links spans belong to it by using context propagation which varies between different scenario.

In process

We use context package to link spans. The root span usually pick context.Background(), and sub spans will inject the context generated by its parent.

//Create a new context
entrySpan, entryCtx, err := h.tracer.CreateEntrySpan(context.Background(), ...)

// Some operation
...

// Link two spans by injecting entrySpan context into exitSpan
exitSpan, err := t.tracer.CreateExitSpan(entryCtx, ...)

Crossing process

We use Entry span to extract context from downstream service, and use Exit span to inject context to upstream service.

Entry and Exit spans make sense to OAP analysis which generates topology map and service metrics.

//Extract context from HTTP request header `sw6`
span, ctx, err := h.tracer.CreateEntrySpan(r.Context(), "/api/login", func() (string, error) {
		return r.Header.Get("sw6"), nil
})

// Some operation
...

// Inject context into HTTP request header `sw6`
span, err := t.tracer.CreateExitSpan(req.Context(), "/service/validate", "tomcat-service:8080", func(header string) error {
		req.Header.Set(propagation.Header, header)
		return nil
})

Tag

We set tags into a span which is stored in the backend, but some tags have special purpose. OAP server may use them to aggregate metrics, generate topology map and etc.

They are defined as constant in root package with prefix Tag.

Plugins

Plugins is integrated with specific framework, for instance, net/http, gRPC, mysql and etc. They are stored in plugins package.

1. HTTP client/server example

License

Apache License 2.0. See LICENSE file for details.

Documentation

Overview

Package go2sky implements a native Apache SkyWalking agent library for Go.

See http://skywalking.apache.org/ for more information about Apache SkyWalking.

Index

• Constants
• type NoopSpan
  • func (*NoopSpan) End()
  • func (*NoopSpan) Error(time.Time, ...string)
  • func (*NoopSpan) Log(time.Time, ...string)
  • func (*NoopSpan) SetComponent(int32)
  • func (*NoopSpan) SetOperationName(string)
  • func (*NoopSpan) SetPeer(string)
  • func (*NoopSpan) SetSpanLayer(common.SpanLayer)
  • func (*NoopSpan) Tag(Tag, string)
• type ReportedSpan
• type Reporter
• type SegmentContext
• type Span
• type SpanOption
  • func WithContext(sc *propagation.SpanContext) SpanOption
  • func WithSpanType(spanType SpanType) SpanOption
• type SpanType
• type Tag
• type Tracer
  • func NewTracer(service string, opts ...TracerOption) (tracer *Tracer, err error)
  • func (t *Tracer) CreateEntrySpan(ctx context.Context, operationName string, extractor propagation.Extractor) (s Span, nCtx context.Context, err error)
  • func (t *Tracer) CreateExitSpan(ctx context.Context, operationName string, peer string, ...) (Span, error)
  • func (t *Tracer) CreateLocalSpan(ctx context.Context, opts ...SpanOption) (s Span, c context.Context, err error)
  • func (t *Tracer) WaitUntilRegister()
• type TracerOption
  • func WithInstance(instance string) TracerOption
  • func WithReporter(reporter Reporter) TracerOption

Examples

• NewTracer

Constants

const ContentKey = "SKY_CONTENT_KEY"

const RefKey = "SKY_REF_KEY"

Types

type NoopSpan

type NoopSpan struct {
}

func (*NoopSpan) End

func (*NoopSpan) End()

func (*NoopSpan) Error

func (*NoopSpan) Error(time.Time, ...string)

func (*NoopSpan) Log

func (*NoopSpan) Log(time.Time, ...string)

func (*NoopSpan) SetComponent

func (*NoopSpan) SetComponent(int32)

func (*NoopSpan) SetOperationName

func (*NoopSpan) SetOperationName(string)

func (*NoopSpan) SetPeer

func (*NoopSpan) SetPeer(string)

func (*NoopSpan) SetSpanLayer

func (*NoopSpan) SetSpanLayer(common.SpanLayer)

func (*NoopSpan) Tag

func (*NoopSpan) Tag(Tag, string)

type ReportedSpan

type ReportedSpan interface {
	Context() *SegmentContext
	Refs() []*propagation.SpanContext
	StartTime() int64
	EndTime() int64
	OperationName() string
	Peer() string
	SpanType() common.SpanType
	SpanLayer() common.SpanLayer
	IsError() bool
	Tags() []*common.KeyStringValuePair
	Logs() []*v2.Log
	ComponentID() int32
}

ReportedSpan is accessed by Reporter to load reported data

type Reporter

type Reporter interface {
	Register(service string, instance string) (int32, int32, error)
	Send(spans []ReportedSpan)
	Close()
}

Reporter is a data transit specification

type SegmentContext

type SegmentContext struct {
	TraceID         []int64
	SegmentID       []int64
	SpanID          int32
	ParentSpanID    int32
	ParentSegmentID []int64
	// contains filtered or unexported fields
}

SegmentContext is the context in a segment

type Span

type Span interface {
	SetOperationName(string)
	SetPeer(string)
	SetSpanLayer(common.SpanLayer)
	SetComponent(int32)
	Tag(Tag, string)
	Log(time.Time, ...string)
	Error(time.Time, ...string)
	End()
}

Span interface as common span specification

type SpanOption

type SpanOption func(s *defaultSpan)

SpanOption allows for functional options to adjust behaviour of a Span to be created by CreateLocalSpan

func WithContext

func WithContext(sc *propagation.SpanContext) SpanOption

WithContext setup trace sc from propagation

func WithSpanType

func WithSpanType(spanType SpanType) SpanOption

WithSpanType setup span type of a span

type SpanType

type SpanType int32

SpanType is used to identify entry, exit and local

const (
	// SpanTypeEntry is a entry span, eg http server
	SpanTypeEntry SpanType = 0
	// SpanTypeExit is a exit span, eg http client
	SpanTypeExit SpanType = 1
	// SpanTypeLocal is a local span, eg local method invoke
	SpanTypeLocal SpanType = 2
)

type Tag

type Tag string

Tag are supported by sky-walking engine. As default, all Tags will be stored, but these ones have particular meanings.

const (
	TagURL             Tag = "url"
	TagStatusCode      Tag = "status_code"
	TagHTTPMethod      Tag = "http.method"
	TagDBType          Tag = "db.type"
	TagDBInstance      Tag = "db.instance"
	TagDBStatement     Tag = "db.statement"
	TagDBBindVariables Tag = "db.bind_vars"
	TagMQQueue         Tag = "mq.queue"
	TagMQBroker        Tag = "mq.broker"
	TagMQTopic         Tag = "mq.topic"
)

type Tracer

type Tracer struct {
	// contains filtered or unexported fields
}

Tracer is go2sky tracer implementation.

func NewTracer

func NewTracer(service string, opts ...TracerOption) (tracer *Tracer, err error)

NewTracer return a new go2sky Tracer

Example

package main

import (
	"context"
	"log"
	"time"

	"github.com/marlonfan/go2sky"
	"github.com/marlonfan/go2sky/reporter"
)

func main() {
	// Use gRPC reporter for production
	r, err := reporter.NewLogReporter()
	if err != nil {
		log.Fatalf("new reporter error %v \n", err)
	}
	defer r.Close()
	tracer, err := go2sky.NewTracer("example", go2sky.WithReporter(r))
	if err != nil {
		log.Fatalf("create tracer error %v \n", err)
	}
	// This for test
	tracer.WaitUntilRegister()
	span, ctx, err := tracer.CreateLocalSpan(context.Background())
	if err != nil {
		log.Fatalf("create new local span error %v \n", err)
	}
	span.SetOperationName("invoke data")
	span.Tag("kind", "outer")
	time.Sleep(time.Second)
	subSpan, _, err := tracer.CreateLocalSpan(ctx)
	if err != nil {
		log.Fatalf("create new sub local span error %v \n", err)
	}
	subSpan.SetOperationName("invoke inner")
	subSpan.Log(time.Now(), "inner", "this is right")
	time.Sleep(time.Second)
	subSpan.End()
	time.Sleep(500 * time.Millisecond)
	span.End()
	time.Sleep(time.Second)
}

func (*Tracer) CreateEntrySpan

func (t *Tracer) CreateEntrySpan(ctx context.Context, operationName string, extractor propagation.Extractor) (s Span, nCtx context.Context, err error)

CreateEntrySpan creates and starts an entry span for incoming request

func (*Tracer) CreateExitSpan

func (t *Tracer) CreateExitSpan(ctx context.Context, operationName string, peer string, injector propagation.Injector) (Span, error)

CreateExitSpan creates and starts an exit span for client

func (*Tracer) CreateLocalSpan

func (t *Tracer) CreateLocalSpan(ctx context.Context, opts ...SpanOption) (s Span, c context.Context, err error)

CreateLocalSpan creates and starts a span for local usage

func (*Tracer) WaitUntilRegister

func (t *Tracer) WaitUntilRegister()

WaitUntilRegister is a tool helps user to wait until register process has finished

type TracerOption

type TracerOption func(t *Tracer)

TracerOption allows for functional options to adjust behaviour of a Tracer to be created by NewTracer

func WithInstance

func WithInstance(instance string) TracerOption

WithInstance setup instance identify

func WithReporter

func WithReporter(reporter Reporter) TracerOption

WithReporter setup report pipeline for tracer