From d563f8d841d3bc05c67c2e3827c7c6bfe56cb969 Mon Sep 17 00:00:00 2001
From: Ronald <ronald-farias@outlook.com>
Date: Tue, 30 Jul 2024 14:53:08 -0300
Subject: [PATCH] refactor: avoid exception when lambda_handler envs not
 present in aws-lambda instrumentation (#2750)

---
 CHANGELOG.md                                       |  4 +++-
 .../instrumentation/aws_lambda/__init__.py         | 10 +++++++++-
 .../test_aws_lambda_instrumentation_manual.py      | 14 ++++++++++++++
 3 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 54452faf3..712aedb93 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,8 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Unreleased
 
-### Fixed
+## Fixed
 
+- `opentelemetry-instrumentation-aws-lambda` Avoid exception when a handler is not present.
+  ([#2750](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/2750))
 - `opentelemetry-instrumentation-django` Fix regression - `http.target` re-added back to old semconv duration metrics
   ([#2746](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/2746))
 - `opentelemetry-instrumentation-grpc` Fixes the issue with the gRPC instrumentation not working with the 1.63.0 and higher version of gRPC
diff --git a/instrumentation/opentelemetry-instrumentation-aws-lambda/src/opentelemetry/instrumentation/aws_lambda/__init__.py b/instrumentation/opentelemetry-instrumentation-aws-lambda/src/opentelemetry/instrumentation/aws_lambda/__init__.py
index c320c12bd..883296d85 100644
--- a/instrumentation/opentelemetry-instrumentation-aws-lambda/src/opentelemetry/instrumentation/aws_lambda/__init__.py
+++ b/instrumentation/opentelemetry-instrumentation-aws-lambda/src/opentelemetry/instrumentation/aws_lambda/__init__.py
@@ -410,7 +410,7 @@ class AwsLambdaInstrumentor(BaseInstrumentor):
         """Instruments Lambda Handlers on AWS Lambda.
 
         See more:
-        https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/trace/semantic_conventions/instrumentation/aws-lambda.md#instrumenting-aws-lambda
+        https://github.com/open-telemetry/semantic-conventions/blob/main/docs/faas/aws-lambda.md
 
         Args:
             **kwargs: Optional arguments
@@ -422,6 +422,14 @@ class AwsLambdaInstrumentor(BaseInstrumentor):
                     request.
         """
         lambda_handler = os.environ.get(ORIG_HANDLER, os.environ.get(_HANDLER))
+        if not lambda_handler:
+            logger.warning(
+                (
+                    "Could not find the ORIG_HANDLER or _HANDLER in the environment variables. ",
+                    "This instrumentation requires the OpenTelemetry Lambda extension installed.",
+                )
+            )
+            return
         # pylint: disable=attribute-defined-outside-init
         (
             self._wrapped_module_name,
diff --git a/instrumentation/opentelemetry-instrumentation-aws-lambda/tests/test_aws_lambda_instrumentation_manual.py b/instrumentation/opentelemetry-instrumentation-aws-lambda/tests/test_aws_lambda_instrumentation_manual.py
index 9f25524e4..00940547e 100644
--- a/instrumentation/opentelemetry-instrumentation-aws-lambda/tests/test_aws_lambda_instrumentation_manual.py
+++ b/instrumentation/opentelemetry-instrumentation-aws-lambda/tests/test_aws_lambda_instrumentation_manual.py
@@ -495,6 +495,20 @@ class TestAwsLambdaInstrumentor(TestBase):
 
         exc_env_patch.stop()
 
+    def test_lambda_handles_should_do_nothing_when_environment_variables_not_present(
+        self,
+    ):
+        exc_env_patch = mock.patch.dict(
+            "os.environ",
+            {_HANDLER: ""},
+        )
+        exc_env_patch.start()
+        AwsLambdaInstrumentor().instrument()
+
+        spans = self.memory_exporter.get_finished_spans()
+        self.assertEqual(len(spans), 0)
+        exc_env_patch.stop()
+
     def test_uninstrument(self):
         AwsLambdaInstrumentor().instrument()