log-example

go.mod

module github.com/teone/log-example

go 1.20

replace (
	github.com/coreos/bbolt v1.3.4 => go.etcd.io/bbolt v1.3.4
	go.etcd.io/bbolt v1.3.4 => github.com/coreos/bbolt v1.3.4
)

require github.com/opencord/voltha-lib-go/v7 v7.4.6

require (
	github.com/opentracing/opentracing-go v1.2.0 // indirect
	github.com/pkg/errors v0.9.1 // indirect
	github.com/uber/jaeger-client-go v2.29.1+incompatible // indirect
	github.com/uber/jaeger-lib v2.4.1+incompatible // indirect
	go.uber.org/atomic v1.7.0 // indirect
	go.uber.org/multierr v1.6.0 // indirect
	go.uber.org/zap v1.18.1 // indirect
)

main.go

package main

import (
	"context"
	"github.com/opencord/voltha-lib-go/v7/pkg/log"
	"github.com/opentracing/opentracing-go"
	"github.com/uber/jaeger-client-go"
	"os"
)

var logger log.CLogger

type Config struct {
	LogLevel              log.LogLevel
	LofFormat             string
	TraceEnabled          bool
	TraceAgentAddress     string
	LogCorrelationEnabled bool
}

func init() {
	// Setup this package so that it's log level can be modified at run time
	var err error
	logger, err = log.RegisterPackage(log.CONSOLE, log.ErrorLevel, log.Fields{})
	if err != nil {
		panic(err)
	}
}

func main() {

	os.Setenv("COMPONENT_NAME", "test-component")
	cf := Config{
		LogLevel:              log.DebugLevel,
		LofFormat:             log.CONSOLE,
		TraceEnabled:          false,
		TraceAgentAddress:     "",
		LogCorrelationEnabled: true,
	}

	instanceID := "test-instance"

	ctx := context.Background()

	tracer, closer := jaeger.NewTracer("service", jaeger.NewConstSampler(true), jaeger.NewNullReporter())
	defer closer.Close()

	sp1 := tracer.StartSpan("package-main").(*jaeger.Span)
	ctx = opentracing.ContextWithSpan(ctx, sp1)

	//Setup default logger - applies for packages that do not have specific logger set
	if _, err := log.SetDefaultLogger(cf.LofFormat, cf.LogLevel, log.Fields{"instanceId": instanceID}); err != nil {
		logger.With(log.Fields{"error": err}).Fatal(ctx, "Cannot setup logging")
	}

	// Update all loggers (provisioned via init) with a common field
	if err := log.UpdateAllLoggers(log.Fields{"instanceId": instanceID}); err != nil {
		logger.With(log.Fields{"error": err}).Fatal(ctx, "Cannot setup logging")
	}

	// Update all loggers to log level specified as input parameter
	log.SetAllLogLevel(cf.LogLevel)

	// setup log correlation
	closer, err := log.GetGlobalLFM().InitTracingAndLogCorrelation(cf.TraceEnabled, cf.TraceAgentAddress, cf.LogCorrelationEnabled)
	if err != nil {
		logger.Warnw(ctx, "unable-to-initialize-tracing-and-log-correlation-module", log.Fields{"error": err})
	} else {
		defer func() {
			err = closer.Close()
			if err != nil {
				logger.Errorw(ctx, "failed-to-close-trace-closer", log.Fields{"error": err})
			}
		}()
	}

	logger.Infow(ctx, "logging-is-setup", log.Fields{"code": 123})
	anotherFn(ctx, tracer)
}

func anotherFn(ctx context.Context, tracer opentracing.Tracer) {
	parentSpan := opentracing.SpanFromContext(ctx)
	sp := tracer.StartSpan(
		"anotherFn",
		opentracing.ChildOf(parentSpan.Context()))
	logger.Infow(opentracing.ContextWithSpan(ctx, sp), "some-log-message-in-another-function", log.Fields{"code": 243})
}

Will log:

2023-11-17T16:44:30.047-0800    info    log-example/main.go:77  logging-is-setup        {"instanceId": "test-instance", "op-id": "65addf9e8be15000", "op-name": "package-main", "code": 123}
2023-11-17T16:44:30.047-0800    info    log-example/main.go:86  some-log-message-in-another-function    {"instanceId": "test-instance", "op-name": "package-main", "task-id": "5205f502002b9e07", "task-name": "anotherFn", "op-id": "65addf9e8be15000", "code": 243}