log.go

package otel

import (
	"context"
	"os"
	"time"

	semconv "go.opentelemetry.io/otel/semconv/v1.12.0"
	"go.opentelemetry.io/otel/trace"
	"golang.org/x/exp/slog"
)

var (
	resourceGroup slog.Attr
	logger        slog.Logger
)

func InitLogger(name, ver, env string) {
	resourceGroup = slog.Group("Resource",
		slog.Attr{
			Key:   string(semconv.ServiceNameKey),
			Value: slog.StringValue(name),
		},
		slog.Attr{
			Key:   string(semconv.ServiceVersionKey),
			Value: slog.StringValue(ver),
		},
		slog.Attr{
			Key:   string(semconv.DeploymentEnvironmentKey),
			Value: slog.StringValue(env),
		},
	)
	// TODO 2022/11/06 @Jimeux custom handler to avoid redundant fields
	logger = slog.New(slog.NewJSONHandler(os.Stdout))
}

func LogErr(ctx context.Context, err error, msg string, attrs ...slog.Attr) {
	traceID, spanID := "none", "none"
	span := trace.SpanFromContext(ctx)
	if span.IsRecording() {
		traceID = span.SpanContext().TraceID().String()
		spanID = span.SpanContext().SpanID().String()
	}

	logger.Error(msg, err,
		slog.Int64("Timestamp", time.Now().UnixNano()),
		slog.String("TraceId", traceID),
		slog.String("SpanId", spanID),
		slog.String("SeverityText", "ERROR"),
		slog.Int("SeverityNumber", 20), // 17-20 = ERROR
		resourceGroup,
		slog.String("Body", msg),
		slog.Group("Attributes", attrs...),
	)
}