fix bug when no child tracer created

deploy/grafana-ds.yaml

@@ -0,0 +1,30 @@
+apiVersion: 1
+
+datasources:
+- name: Prometheus
+  type: prometheus
+  uid: prometheus
+  access: proxy
+  orgId: 1
+  url: http://prometheus:9090
+  basicAuth: false
+  isDefault: false
+  version: 1
+  editable: false
+  jsonData:
+    httpMethod: GET
+- name: Tempo
+  type: tempo
+  access: proxy
+  orgId: 1
+  url: http://tempo:3200
+  basicAuth: false
+  isDefault: true
+  version: 1
+  editable: false
+  apiVersion: 1
+  uid: tempo
+  jsonData:
+    httpMethod: GET
+    serviceMap:
+      datasourceUid: prometheus

docker-compose.yaml

@@ -18,6 +18,7 @@ services:
       - "host.docker.internal:host-gateway"
     volumes:
       - grafana-volume:/var/lib/grafana
+      - ./deploy/grafana-ds.yaml:/etc/grafana/provisioning/datasources/datasources.yaml
 
   prometheus:
     image: prom/prometheus:v2.54.0

src/app.go

@@ -24,7 +24,8 @@ import (
 	"time"
 
 	"go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp"
-	"go.opentelemetry.io/otel/sdk/trace"
+	traceSdk "go.opentelemetry.io/otel/sdk/trace"
+	"go.opentelemetry.io/otel/trace"
 )
 
 type App struct{}
@@ -105,6 +106,24 @@ func (a *App) Run(p RunParams) {
 		}
 	}
 
+	var tracer trace.Tracer
+	{
+		tracerExporter, err := otlptracehttp.New(context.Background(), otlptracehttp.WithEndpointURL("http://localhost:4318"))
+		if err != nil {
+			logger.Fatal().Err(err).Msg("failed initializing tracer")
+		}
+
+		tracerProvider := traceSdk.NewTracerProvider(
+			traceSdk.WithSampler(traceSdk.AlwaysSample()),
+			traceSdk.WithBatcher(
+				tracerExporter,
+				traceSdk.WithMaxQueueSize(4096),
+				traceSdk.WithMaxExportBatchSize(1024),
+			),
+		)
+		tracer = tracerProvider.Tracer("backend")
+	}
+
 	// Build business-logic objects
 	var (
 		userService      services.UserService
@@ -115,7 +134,7 @@ func (a *App) Run(p RunParams) {
 			jwtUtil      = utils.NewJwtUtil(key)
 			passwordUtil = utils.NewPasswordUtil()
 
-			userRepo        = repos.NewUserRepo(sqlDb)
+			userRepo        = repos.NewUserRepo(sqlDb, tracer)
 			emailRepo       = repos.NewEmailRepo()
 			actionTokenRepo = repos.NewActionTokenRepo(sqlDb)
 
@@ -163,17 +182,6 @@ func (a *App) Run(p RunParams) {
 
 	clientNotifier := client_notifier.NewBasicNotifier()
 
-	tracerExporter, err := otlptracehttp.New(context.Background(), otlptracehttp.WithEndpointURL("http://localhost:4318"))
-	if err != nil {
-		logger.Fatal().Err(err).Msg("failed initializing tracer")
-	}
-	tracerProvider := trace.NewTracerProvider(
-		trace.WithSampler(trace.AlwaysSample()),
-		trace.WithBatcher(tracerExporter),
-	)
-
-	tracer := tracerProvider.Tracer("backend")
-
 	// Start profiling
 	if args.GetProfilePath() != "" {
 		pprofFile, err := os.Create(args.GetProfilePath())

src/core/repos/user_repo.go

@@ -6,6 +6,8 @@ import (
 	"context"
 	"database/sql"
 	"errors"
+
+	"go.opentelemetry.io/otel/trace"
 )
 
 // type userDAO struct {
@@ -22,15 +24,19 @@ type UserRepo interface {
 	GetUserByEmail(ctx context.Context, login string) (*models.UserDTO, error)
 }
 
-func NewUserRepo(db integrations.SqlDB) UserRepo {
-	return &userRepo{db}
+func NewUserRepo(db integrations.SqlDB, tracer trace.Tracer) UserRepo {
+	return &userRepo{db, tracer}
 }
 
 type userRepo struct {
-	db integrations.SqlDB
+	db     integrations.SqlDB
+	tracer trace.Tracer
 }
 
 func (u *userRepo) CreateUser(ctx context.Context, dto models.UserDTO) (*models.UserDTO, error) {
+	_, span := u.tracer.Start(ctx, "postgres")
+	defer span.End()
+
 	query := `insert into users (email, secret, name) values ($1, $2, $3) returning id;`
 	row := u.db.QueryRowContext(ctx, query, dto.Email, dto.Secret, dto.Name)
 
@@ -48,6 +54,9 @@ func (u *userRepo) CreateUser(ctx context.Context, dto models.UserDTO) (*models.
 }
 
 func (u *userRepo) UpdateUser(ctx context.Context, userId string, dto models.UserUpdateDTO) error {
+	_, span := u.tracer.Start(ctx, "postgres")
+	defer span.End()
+
 	query := `update users set secret=$1, name=$2 where id = $3;`
 	_, err := u.db.ExecContext(ctx, query, dto.Secret, dto.Name, userId)
 	if err != nil {
@@ -58,6 +67,9 @@ func (u *userRepo) UpdateUser(ctx context.Context, userId string, dto models.Use
 }
 
 func (u *userRepo) GetUserById(ctx context.Context, id string) (*models.UserDTO, error) {
+	_, span := u.tracer.Start(ctx, "postgres")
+	defer span.End()
+
 	query := `select id, email, secret, name from users where id = $1;`
 	row := u.db.QueryRowContext(ctx, query, id)
 
@@ -74,6 +86,9 @@ func (u *userRepo) GetUserById(ctx context.Context, id string) (*models.UserDTO,
 }
 
 func (u *userRepo) GetUserByEmail(ctx context.Context, login string) (*models.UserDTO, error) {
+	_, span := u.tracer.Start(ctx, "postgres")
+	defer span.End()
+
 	query := `select id, email, secret, name from users where email = $1;`
 	row := u.db.QueryRowContext(ctx, query, login)
 

src/server/middleware/request_log.go

@@ -7,7 +7,6 @@ import (
 
 	"github.com/gin-gonic/gin"
 	"github.com/google/uuid"
-	"go.opentelemetry.io/otel/attribute"
 	"go.opentelemetry.io/otel/trace"
 )
 
@@ -16,15 +15,11 @@ func NewRequestLogMiddleware(logger log.Logger, tracer trace.Tracer, prometheus
 		prometheus.RequestInc()
 		defer prometheus.RequestDec()
 
-		_, span := tracer.Start(c.Request.Context(), c.Request.URL.Path)
-		defer span.End()
-
 		requestId := c.GetHeader("X-Request-Id")
 		if requestId == "" {
 			requestId = uuid.New().String()
 		}
 
-		span.SetAttributes(attribute.String("requestId", c.ClientIP()))
 		log.SetCtxRequestId(c, requestId)
 
 		path := c.Request.URL.Path

src/server/middleware/tracing.go

@@ -2,16 +2,26 @@ package middleware
 
 import (
 	"github.com/gin-gonic/gin"
-	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel"
+	"go.opentelemetry.io/otel/propagation"
 	"go.opentelemetry.io/otel/trace"
 )
 
 func NewTracingMiddleware(tracer trace.Tracer) gin.HandlerFunc {
+	prop := otel.GetTextMapPropagator()
+
 	return func(c *gin.Context) {
-		_, span := tracer.Start(c.Request.Context(), c.Request.URL.Path)
+		savedCtx := c.Request.Context()
+		defer func() {
+			c.Request = c.Request.WithContext(savedCtx)
+		}()
+
+		ctx := prop.Extract(savedCtx, propagation.HeaderCarrier(c.Request.Header))
+
+		ctx, span := tracer.Start(ctx, c.Request.URL.Path)
 		defer span.End()
 
-		span.SetAttributes(attribute.String("requestId", c.ClientIP()))
+		c.Request = c.Request.WithContext(ctx)
 
 		c.Next()
 	}

src/server/server.go

@@ -35,6 +35,8 @@ func New(opts NewServerOpts) *Server {
 	}
 
 	r := gin.New()
+	r.ContextWithFallback = true // Use it to allow getting values from c.Request.Context()
+
 	r.Static("/webapp", "./webapp")
 	r.GET("/health", handlers.NewDummyHandler())
 
@@ -43,6 +45,7 @@ func New(opts NewServerOpts) *Server {
 
 	r.Use(middleware.NewRecoveryMiddleware(opts.Logger, prometheus, opts.DebugMode))
 	r.Use(middleware.NewRequestLogMiddleware(opts.Logger, opts.Tracer, prometheus))
+	r.Use(middleware.NewTracingMiddleware(opts.Tracer))
 
 	r.GET("/pooling", handlers.NewLongPoolingHandler(opts.Logger, opts.Notifier))