feat: use postgres

pkg/postgres/otel.go

@@ -0,0 +1,38 @@
+package postgres
+
+import (
+	"database/sql"
+	"errors"
+	"fmt"
+
+	"github.com/XSAM/otelsql"
+)
+
+// Unregister releases an instrumentation registration. Returned by
+// InstrumentDBStats so callers can detach metrics during shutdown.
+type Unregister func() error
+
+// InstrumentDBStats registers `database/sql` connection-pool metrics
+// (`db.sql.connection.*`) for db. Statement spans are already attached at open
+// time inside OpenPrimary/OpenReplicas — this function adds the meter-side
+// instrumentation.
+//
+// The returned Unregister detaches the metric callbacks; callers usually
+// invoke it during shutdown after closing db.
+func InstrumentDBStats(db *sql.DB, opts ...Option) (Unregister, error) {
+	if db == nil {
+		return nil, errors.New("instrument postgres db stats: nil db")
+	}
+
+	resolved := evalOptions(opts)
+	otelOpts := []otelsql.Option{otelsql.WithAttributes(dbSystemAttribute)}
+	if resolved.meterProvider != nil {
+		otelOpts = append(otelOpts, otelsql.WithMeterProvider(resolved.meterProvider))
+	}
+
+	reg, err := otelsql.RegisterDBStatsMetrics(db, otelOpts...)
+	if err != nil {
+		return nil, fmt.Errorf("instrument postgres db stats: %w", err)
+	}
+	return reg.Unregister, nil
+}