Fix multiple env accessing for same key.

Author: purple4reina

datadog_lambda/config.py

@@ -49,10 +49,6 @@ class Config:
     service = _get_env("DD_SERVICE")
     env = _get_env("DD_ENV")
 
-    function_name = _get_env("AWS_LAMBDA_FUNCTION_NAME", "function")
-    is_gov_region = _get_env("AWS_REGION", "", lambda x: x.startswith("us-gov-"))
-    is_lambda_context = _get_env("AWS_LAMBDA_FUNCTION_NAME", None, bool)
-
     cold_start_tracing = _get_env(
         "DD_COLD_START_TRACING", "true", as_bool, depends_on_tracing=True
     )
@@ -94,9 +90,28 @@ class Config:
     llmobs_enabled = _get_env("DD_LLMOBS_ENABLED", "false", as_bool)
     exception_replay_enabled = _get_env("DD_EXCEPTION_REPLAY_ENABLED", "false", as_bool)
 
+    is_gov_region = _get_env("AWS_REGION", "", lambda x: x.startswith("us-gov-"))
+
     local_test = _get_env("DD_LOCAL_TEST", "false", as_bool)
     integration_test = _get_env("DD_INTEGRATION_TEST", "false", as_bool)
 
+    aws_lambda_function_name = _get_env("AWS_LAMBDA_FUNCTION_NAME")
+
+    @property
+    def function_name(self):
+        if not hasattr(self, "_config_function_name"):
+            if self.aws_lambda_function_name is None:
+                self._config_function_name = "function"
+            else:
+                self._config_function_name = self.aws_lambda_function_name
+        return self._config_function_name
+
+    @property
+    def is_lambda_context(self):
+        if not hasattr(self, "_config_is_lambda_context"):
+            self._config_is_lambda_context = bool(self.aws_lambda_function_name)
+        return self._config_is_lambda_context
+
     @property
     def fips_mode_enabled(self):
         if not hasattr(self, "_config_fips_mode_enabled"):

tests/test_config.py

@@ -99,16 +99,24 @@ def _test_as_list(env_key, conf_key, default):
     ("DD_SERVICE", "service", None, None),
     ("DD_SERVICE", "service", "", ""),
     ("DD_SERVICE", "service", "my_service", "my_service"),
+    ("AWS_LAMBDA_FUNCTION_NAME", "aws_lambda_function_name", None, None),
+    ("AWS_LAMBDA_FUNCTION_NAME", "aws_lambda_function_name", "", ""),
+    (
+        "AWS_LAMBDA_FUNCTION_NAME",
+        "aws_lambda_function_name",
+        "my_function",
+        "my_function",
+    ),
     ("AWS_LAMBDA_FUNCTION_NAME", "function_name", None, "function"),
     ("AWS_LAMBDA_FUNCTION_NAME", "function_name", "", ""),
     ("AWS_LAMBDA_FUNCTION_NAME", "function_name", "my_function", "my_function"),
+    ("AWS_LAMBDA_FUNCTION_NAME", "is_lambda_context", None, False),
+    ("AWS_LAMBDA_FUNCTION_NAME", "is_lambda_context", "", False),
+    ("AWS_LAMBDA_FUNCTION_NAME", "is_lambda_context", "my_function", True),
     ("AWS_REGION", "is_gov_region", None, False),
     ("AWS_REGION", "is_gov_region", "", False),
     ("AWS_REGION", "is_gov_region", "us-gov-1", True),
     ("AWS_REGION", "is_gov_region", "us-est-1", False),
-    ("AWS_LAMBDA_FUNCTION_NAME", "is_lambda_context", None, False),
-    ("AWS_LAMBDA_FUNCTION_NAME", "is_lambda_context", "", False),
-    ("AWS_LAMBDA_FUNCTION_NAME", "is_lambda_context", "my_function", True),
     ("DD_TRACE_EXTRACTOR", "trace_extractor", None, None),
     ("DD_TRACE_EXTRACTOR", "trace_extractor", "", ""),
     ("DD_TRACE_EXTRACTOR", "trace_extractor", "my_extractor", "my_extractor"),
@@ -147,6 +155,15 @@ def test_config_from_environ_depends_on_tracing(
     assert getattr(config, conf_key) is False
 
 
+def test_config_aws_lambda_function_name(setenv):
+    # these config values all access the same environment variable, test to
+    # ensure the wrong value is not cached
+    setenv("AWS_LAMBDA_FUNCTION_NAME", "my_function")
+    assert config.aws_lambda_function_name == "my_function"
+    assert config.function_name == "my_function"
+    assert config.is_lambda_context is True
+
+
 _test_fips_mode_from_environ = (
     (None, None, False),
     (None, "", False),