Include exception information for failed statements.

Author: carlosalberto

sqlalchemy_opentracing/__init__.py

@@ -171,6 +171,8 @@ def _engine_error_handler(exception_context):
     if span is None:
         return
 
+    exc = exception_context.original_exception
+    span.set_tag('sqlalchemy.exception', str(exc))
     span.set_tag('error', 'true')
     span.finish()
 

tests/test_core.py

@@ -74,6 +74,7 @@ def test_traced_error(self):
             'db.statement': 'CREATE TABLE users (id INTEGER NOT NULL, name VARCHAR, PRIMARY KEY (id))',
             'db.type': 'sql',
             'sqlalchemy.dialect': 'sqlite',
+            'sqlalchemy.exception': 'table users already exists',
             'error': 'true',
         })
 

tests/test_orm.py

@@ -93,6 +93,7 @@ def test_traced_error(self):
             'db.statement': 'INSERT INTO users (id, name) VALUES (?, ?)',
             'db.type': 'sql',
             'sqlalchemy.dialect': 'sqlite',
+            'sqlalchemy.exception': 'UNIQUE constraint failed: users.id',
             'error': 'true',
         })