AWS Lambda: ARN Normalization (#242)

Author: pglombardo

instana/agent/aws_lambda.py

@@ -53,7 +53,7 @@ def get_from_structure(self):
         Retrieves the From data that is reported alongside monitoring data.
         @return: dict()
         """
-        return {'hl': True, 'cp': 'aws', 'e': self.collector.context.invoked_function_arn}
+        return {'hl': True, 'cp': 'aws', 'e': self.collector.get_fq_arn()}
 
     def report_data_payload(self, payload):
         """
@@ -65,7 +65,7 @@ def report_data_payload(self, payload):
                 # Prepare request headers
                 self.report_headers = dict()
                 self.report_headers["Content-Type"] = "application/json"
-                self.report_headers["X-Instana-Host"] = self.collector.context.invoked_function_arn
+                self.report_headers["X-Instana-Host"] = self.collector.get_fq_arn()
                 self.report_headers["X-Instana-Key"] = self.options.agent_key
                 self.report_headers["X-Instana-Time"] = str(round(time.time() * 1000))
 

instana/collector.py

@@ -3,7 +3,7 @@
 import threading
 
 from .log import logger
-from .util import every, DictionaryOfStan
+from .util import every, DictionaryOfStan, normalize_aws_lambda_arn
 
 
 if sys.version_info.major == 2:
@@ -24,6 +24,7 @@ def __init__(self, agent):
         self.snapshot_data = None
         self.snapshot_data_sent = False
         self.lock = threading.Lock()
+        self._fq_arn = None
 
     def start(self):
         if self.agent.can_send():
@@ -87,13 +88,24 @@ def collect_snapshot(self, event, context):
         try:
             plugin_data = dict()
             plugin_data["name"] = "com.instana.plugin.aws.lambda"
-            plugin_data["entityId"] = self.context.invoked_function_arn
+            plugin_data["entityId"] = self.get_fq_arn()
             self.snapshot_data["plugins"] = [plugin_data]
         except:
             logger.debug("collect_snapshot error", exc_info=True)
         finally:
             return self.snapshot_data
 
+    def get_fq_arn(self):
+        if self._fq_arn is not None:
+            return self._fq_arn
+
+        if self.context is None:
+            logger.debug("Attempt to get qualified ARN before the context object is available")
+            return ''
+
+        self._fq_arn = normalize_aws_lambda_arn(self.context)
+        return self._fq_arn
+
     def __queued_spans(self):
         """ Get all of the spans in the queue """
         span = None

instana/instrumentation/aws/triggers.py

@@ -119,7 +119,7 @@ def enrich_lambda_span(agent, span, event, context):
     @return: None
     """
     try:
-        span.set_tag('lambda.arn', context.invoked_function_arn)
+        span.set_tag('lambda.arn', agent.collector.get_fq_arn())
         span.set_tag('lambda.name', context.function_name)
         span.set_tag('lambda.version', context.function_version)
 

instana/util.py

@@ -374,3 +374,30 @@ def determine_service_name():
     except Exception as e:
         logger.debug("get_application_name: ", exc_info=True)
         return app_name
+
+
+def normalize_aws_lambda_arn(context):
+    """
+    Parse the AWS Lambda context object for a fully qualified AWS Lambda function ARN.
+
+    This method will ensure that the returned value matches the following ARN pattern:
+      arn:aws:lambda:${region}:${account-id}:function:${name}:${version}
+
+    @param context:  AWS Lambda context object
+    @return:
+    """
+    try:
+        arn = context.invoked_function_arn
+        parts = arn.split(':')
+
+        count = len(parts)
+        if count == 7:
+            # need to append version
+            arn = arn + ':' + context.function_version
+        elif count != 8:
+            logger.debug("Unexpected ARN parse issue: %s", arn)
+
+        return arn
+    except:
+        logger.debug("normalize_arn: ", exc_info=True)
+

tests/platforms/test_lambda.py

@@ -15,12 +15,13 @@
 from instana.instrumentation.aws.lambda_inst import lambda_handler_with_instana
 from instana.instrumentation.aws.triggers import read_http_query_params
 from instana.singletons import get_agent, set_agent, get_tracer, set_tracer
+from instana.util import normalize_aws_lambda_arn
 
 
 # Mock Context object
-class TestContext(dict):
+class MockContext(dict):
     def __init__(self, **kwargs):
-        super(TestContext, self).__init__(**kwargs)
+        super(MockContext, self).__init__(**kwargs)
         self.invoked_function_arn = "arn:aws:lambda:us-east-2:12345:function:TestPython:1"
         self.function_name = "TestPython"
         self.function_version = "1"
@@ -52,7 +53,7 @@ def setUp(self):
         os.environ["LAMBDA_HANDLER"] = "tests.platforms.test_lambda.my_lambda_handler"
         os.environ["INSTANA_ENDPOINT_URL"] = "https://localhost/notreal"
         os.environ["INSTANA_AGENT_KEY"] = "Fake_Key"
-        self.context = TestContext()
+        self.context = MockContext()
 
     def tearDown(self):
         """ Reset all environment variables of consequence """
@@ -535,3 +536,16 @@ def test_read_query_params_with_bad_event(self):
         event = None
         params = read_http_query_params(event)
         self.assertEqual("", params)
+
+    def test_arn_parsing(self):
+        ctx = MockContext()
+
+        assert(normalize_aws_lambda_arn(ctx) == "arn:aws:lambda:us-east-2:12345:function:TestPython:1")
+
+        # Without version should return a fully qualified ARN (with version)
+        ctx.invoked_function_arn = "arn:aws:lambda:us-east-2:12345:function:TestPython"
+        assert(normalize_aws_lambda_arn(ctx) == "arn:aws:lambda:us-east-2:12345:function:TestPython:1")
+
+        # Fully qualified already with the '$LATEST' special tag
+        ctx.invoked_function_arn = "arn:aws:lambda:us-east-2:12345:function:TestPython:$LATEST"
+        assert(normalize_aws_lambda_arn(ctx) == "arn:aws:lambda:us-east-2:12345:function:TestPython:$LATEST")