go-trace

Logging & tracing utilities for micro services.

Based on:

• go.uber.org/zap
• go.opencensus.io/trace
• go.opentelemetry.io/otel

Tested to be compatible wih Datadog tracing.

Logging

The main idea is to unify logging and tracing, and insulate the app layer from the intricacies of tracing.

This repositories provides a few wrappers around a zap.Logger:

• a logger factory based on zap logger, with a convenient builder to link logs to trace spans
• a logger builder, e.g. to initialize a root logger for your service

TODOs:

• [] explore how to expose zerolog as an alternative to zap

Usage

With OpenCensus tracing.

import (
    "context"

    "github.com/fredbi/go-trace/log"
	"go.opencensus.io/trace"
)

func tracedFunc() {
    ctx := context.Background()
    zlg, closer := log.MustGetLogger("root") // builds a named zap logger with sensible defaults
    defer closer()

    lgf := log.NewFactory(zlg) // builds a logger with trace propagation

    ctx, span := trace.StartSpan(ctx, "span name")
    defer span.End()
    lg := lgf.For(ctx)

    lg.Info("log propagated as a trace span")
}

With OpenTelemetry tracing.

import (
    "context"

    "github.com/fredbi/go-trace/log"
	"go.opentelemetry.io/otel"
)


func tracedFunc() {
    tracer := otel.Tracer("") // returns the global default tracer
    ctx := context.Background()
    zlg, closer := log.MustGetLogger("root")
    defer closer()

    lgf := log.NewFactory(zlg) // builds a logger with trace propagation

    ctx, span := tracer.Start(ctx, "span name")
    defer span.End()
    lg := lgf.For(ctx)

    lg.Info("log propagated as a trace span")
}

Full example

Tracing

A simple wrapper to instrument tracing in apps with minimal boiler-plate.

With OpenCensus tracing.

import (
    "context"

    "github.com/fredbi/go-trace/log"
    "github.com/fredbi/go-trace/opencensus/tracer"
)

type loggable struct {
    lgf log.Factory
}

func (l *loggable) Logger() log.Factory {
    return l.lgf
}

func tracedFunc() {
    zlg := log.MustGetLogger("root") // builds a named zap logger with sensible defaults
    lgf := log.NewFactory(zlg) // builds a logger with trace propagation
    component := loggable{lfg:  lgf}

    ctx, span, lg := tracer.StartSpan(context.Background(), component) // the span is named automatically from the calling function
    defer span.End()

    lg.Info("log propagated as a trace span")
}

Full example

With OpenTelemetry tracing.

import (
    "context"

    "github.com/fredbi/go-trace/log"
    "github.com/fredbi/go-trace/otel/tracer"
)

type loggable struct {
    lgf log.Factory
    tracer trace.Tracer
}

func (l *loggable) Logger() log.Factory {
    return l.lgf
}

// Tracer returns the configured tracer. If this method, is not provided,
// the default globally registered OTEL tracer is returned.
func (l *loggable) Tracer() trace.Tracer {
    return l.tracer 
}

func tracedFunc() {
    zlg := log.MustGetLogger("root") // builds a named zap logger with sensible defaults
    lgf := log.NewFactory(zlg, log.WithOTEL(true)) // builds a logger with trace propagation
    component := loggable{lfg:  lgf}

    ctx, span, lg := tracer.StartSpan(context.Background(), component) // the span is named automatically from the calling function
    defer span.End()

    lg.Info("log propagated as a trace span")
}

Full example

Middleware

• middleware.LogRequests logs all requests from a http server, using the logger factory

• opencensus/middleware.OCHTTP wraps the ochttp opencensus plugin into a more convenient middleware function.

• otel/middleware.OTELHTTP wraps the otelhttp OTEL contrib plugin.

Exporters

Mock trace exporters for opencensus and OTEL.

Misc

Various opencensus exporters (as a separate module).

• misc/influxdb: export opencensus metrics to an influxdb sink
• misc/amplitude (experimental): propagate trace event to the amplitude API

Credits

Much inspired by prior art from @casualjim. Thanks so much.