contrib/database/sql: prevent DBM propagation full mode with incompatible dbs

contrib/database/sql/propagation_test.go

@@ -288,6 +288,33 @@ func TestDBMTraceContextTagging(t *testing.T) {
 	}
 }
 
+func TestDBMPropagation_PreventFullMode(t *testing.T) {
+	tr := mocktracer.Start()
+	defer tr.Stop()
+
+	// test we prevent full mode with incompatible drivers
+	driverName := "sqlserver"
+	opts := []Option{WithDBMPropagation(tracer.DBMPropagationModeFull)}
+	// use the mock driver, as the real mssql driver does not implement Execer and Querier interfaces and always falls back
+	// to Prepare which always uses service propagation mode, so we can't test whether the DBM propagation mode gets downgraded or not.
+	Register(driverName, &internal.MockDriver{}, opts...)
+	defer unregister(driverName)
+
+	db, err := Open(driverName, "sqlserver://sa:myPassw0rd@127.0.0.1:1433?database=master", opts...)
+	require.NoError(t, err)
+	defer db.Close()
+
+	s, ctx := tracer.StartSpanFromContext(context.Background(), "test.call", tracer.WithSpanID(1))
+	_, err = db.ExecContext(ctx, "SELECT * FROM INFORMATION_SCHEMA.TABLES")
+	require.NoError(t, err)
+	s.Finish()
+
+	spans := tr.FinishedSpans()
+	for _, s := range spansOfType(spans, QueryTypeExec) {
+		assert.NotContains(t, s.Tags(), keyDBMTraceInjected)
+	}
+}
+
 func spansOfType(spans []mocktracer.Span, spanType string) (filtered []mocktracer.Span) {
 	filtered = make([]mocktracer.Span, 0)
 	for _, s := range spans {

contrib/database/sql/sql.go

@@ -123,9 +123,7 @@ func Register(driverName string, driver driver.Driver, opts ...RegisterOption) {
 
 	cfg := new(config)
 	defaults(cfg, driverName, nil)
-	for _, fn := range opts {
-		fn(cfg)
-	}
+	processOptions(cfg, driverName, opts...)
 	log.Debug("contrib/database/sql: Registering driver: %s %#v", driverName, cfg)
 	registeredDrivers.add(driverName, driver, cfg)
 }
@@ -196,9 +194,7 @@ func OpenDB(c driver.Connector, opts ...Option) *sql.DB {
 		driverName = reflect.TypeOf(c.Driver()).String()
 		defaults(cfg, driverName, nil)
 	}
-	for _, fn := range opts {
-		fn(cfg)
-	}
+	processOptions(cfg, driverName, opts...)
 	tc := &tracedConnector{
 		connector:  c,
 		driverName: driverName,
@@ -236,3 +232,29 @@ func Open(driverName, dataSourceName string, opts ...Option) (*sql.DB, error) {
 	}
 	return OpenDB(&dsnConnector{dsn: dataSourceName, driver: d}, opts...), nil
 }
+
+func processOptions(cfg *config, driverName string, opts ...Option) {
+	for _, fn := range opts {
+		fn(cfg)
+	}
+	checkDBMPropagation(cfg, driverName)
+}
+
+func checkDBMPropagation(cfg *config, driverName string) {
+	fullModeSupported := func() bool {
+		unsupportedDrivers := []string{"sqlserver", "oracle"}
+		for _, dr := range unsupportedDrivers {
+			if dr == driverName {
+				return false
+			}
+		}
+		return true
+	}
+	if cfg.dbmPropagationMode == tracer.DBMPropagationModeFull && !fullModeSupported() {
+		log.Warn("Using DBM_PROPAGATION_MODE in 'full' mode is not supported for %s. See "+
+			"https://docs.datadoghq.com/database_monitoring/connect_dbm_and_apm/ for more info.",
+			driverName,
+		)
+		cfg.dbmPropagationMode = tracer.DBMPropagationModeService
+	}
+}