refactor: raise exception when lambda_handler envs not present in aws…

…-lambda instrumentation

instrumentation/opentelemetry-instrumentation-aws-lambda/src/opentelemetry/instrumentation/aws_lambda/__init__.py

@@ -422,6 +422,13 @@ def _instrument(self, **kwargs):
                     request.
         """
         lambda_handler = os.environ.get(ORIG_HANDLER, os.environ.get(_HANDLER))
+        if not lambda_handler:
+            raise ValueError(
+                (
+                    "Could not find the ORIG_HANDLER or _HANDLER in the environment variables. ",
+                    "This instrumentation is runnning inside an aws lambda?",
+                )
+            )
         # pylint: disable=attribute-defined-outside-init
         (
             self._wrapped_module_name,

instrumentation/opentelemetry-instrumentation-aws-lambda/tests/test_aws_lambda_instrumentation_manual.py

@@ -495,6 +495,22 @@ def test_lambda_handles_handler_exception_with_api_gateway_proxy_event(
 
         exc_env_patch.stop()
 
+    def test_lambda_handles_raises_exception_when_environment_variables_not_present(
+        self,
+    ):
+        exc_env_patch = mock.patch.dict(
+            "os.environ",
+            {_HANDLER: ""},
+        )
+        exc_env_patch.start()
+
+        with self.assertRaises(Exception):
+            AwsLambdaInstrumentor().instrument()
+
+        spans = self.memory_exporter.get_finished_spans()
+        self.assertEqual(len(spans), 0)
+        exc_env_patch.stop()
+
     def test_uninstrument(self):
         AwsLambdaInstrumentor().instrument()