From c31bd4b320693996b2ffc0881038abb63fdff15c Mon Sep 17 00:00:00 2001
From: Owais Lone <owais@lone.pw>
Date: Sat, 8 May 2021 02:48:15 +0530
Subject: [PATCH] Add support for OTEL_SERVICE_NAME env var.

Spec PR: https://github.com/open-telemetry/opentelemetry-specification/pull/1677
---
 CHANGELOG.md                                  |  2 +
 .../sdk/environment_variables/__init__.py     | 17 ++++++++
 .../opentelemetry/sdk/resources/__init__.py   |  8 +++-
 .../tests/resources/test_resources.py         | 39 +++++++++++++++++++
 4 files changed, 65 insertions(+), 1 deletion(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 164a02b669a..c5544d57249 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -9,6 +9,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Added
 - Added example for running Django with auto instrumentation.
   ([#1803](https://github.com/open-telemetry/opentelemetry-python/pull/1803))
+- Added support for OTEL_SERVICE_NAME.
+  ([#1829](https://github.com/open-telemetry/opentelemetry-python/pull/1829))
 
 ### Changed
 - Fixed OTLP gRPC exporter silently failing if scheme is not specified in endpoint.
diff --git a/opentelemetry-sdk/src/opentelemetry/sdk/environment_variables/__init__.py b/opentelemetry-sdk/src/opentelemetry/sdk/environment_variables/__init__.py
index 9289d1c44ad..a113d705e4f 100644
--- a/opentelemetry-sdk/src/opentelemetry/sdk/environment_variables/__init__.py
+++ b/opentelemetry-sdk/src/opentelemetry/sdk/environment_variables/__init__.py
@@ -218,3 +218,20 @@
 """
 .. envvar:: OTEL_EXPORTER_JAEGER_AGENT_SPLIT_OVERSIZED_BATCHES
 """
+
+OTEL_SERVICE_NAME = "OTEL_SERVICE_NAME"
+"""
+.. envvar:: OTEL_SERVICE_NAME
+
+Convenience environment variable for setting the service name resource attribute.
+The following two environment variables have the same effect
+
+.. code-block:: console
+
+    OTEL_SERVICE_NAME=my-python-service
+
+    OTEL_RESOURCE_ATTRIBUTES=service.name=my-python-service
+
+
+If both are set, :envvar:`OTEL_SERVICE_NAME` take precedence.
+"""
diff --git a/opentelemetry-sdk/src/opentelemetry/sdk/resources/__init__.py b/opentelemetry-sdk/src/opentelemetry/sdk/resources/__init__.py
index 6cffff42639..77240b8ef8e 100644
--- a/opentelemetry-sdk/src/opentelemetry/sdk/resources/__init__.py
+++ b/opentelemetry-sdk/src/opentelemetry/sdk/resources/__init__.py
@@ -64,7 +64,10 @@
 
 import pkg_resources
 
-from opentelemetry.sdk.environment_variables import OTEL_RESOURCE_ATTRIBUTES
+from opentelemetry.sdk.environment_variables import (
+    OTEL_RESOURCE_ATTRIBUTES,
+    OTEL_SERVICE_NAME,
+)
 from opentelemetry.semconv.resource import ResourceAttributes
 
 LabelValue = typing.Union[str, bool, int, float]
@@ -231,6 +234,9 @@ def detect(self) -> "Resource":
                     item.split("=") for item in env_resources_items.split(",")
                 )
             }
+        service_name = os.environ.get(OTEL_SERVICE_NAME)
+        if service_name:
+            env_resource_map[SERVICE_NAME] = service_name
         return Resource(env_resource_map)
 
 
diff --git a/opentelemetry-sdk/tests/resources/test_resources.py b/opentelemetry-sdk/tests/resources/test_resources.py
index 4b8fd71da27..211187f1ebb 100644
--- a/opentelemetry-sdk/tests/resources/test_resources.py
+++ b/opentelemetry-sdk/tests/resources/test_resources.py
@@ -232,6 +232,20 @@ def test_env_priority(self):
         self.assertEqual(resource_env_override.attributes["key1"], "value1")
         self.assertEqual(resource_env_override.attributes["key2"], "value2")
 
+    @mock.patch.dict(
+        os.environ,
+        {
+            resources.OTEL_SERVICE_NAME: "test-srv-name",
+            resources.OTEL_RESOURCE_ATTRIBUTES: "service.name=svc-name-from-resource",
+        },
+    )
+    def test_service_name_env(self):
+        resource = resources.Resource.create()
+        self.assertEqual(resource.attributes["service.name"], "test-srv-name")
+
+        resource = resources.Resource.create({"service.name": "from-code"})
+        self.assertEqual(resource.attributes["service.name"], "from-code")
+
 
 class TestOTELResourceDetector(unittest.TestCase):
     def setUp(self) -> None:
@@ -270,3 +284,28 @@ def test_multiple_with_whitespace(self):
         self.assertEqual(
             detector.detect(), resources.Resource({"k": "v", "k2": "v2"})
         )
+
+    @mock.patch.dict(
+        os.environ,
+        {resources.OTEL_SERVICE_NAME: "test-srv-name"},
+    )
+    def test_service_name_env(self):
+        detector = resources.OTELResourceDetector()
+        self.assertEqual(
+            detector.detect(),
+            resources.Resource({"service.name": "test-srv-name"}),
+        )
+
+    @mock.patch.dict(
+        os.environ,
+        {
+            resources.OTEL_SERVICE_NAME: "from-service-name",
+            resources.OTEL_RESOURCE_ATTRIBUTES: "service.name=from-resource-attrs",
+        },
+    )
+    def test_service_name_env_precedence(self):
+        detector = resources.OTELResourceDetector()
+        self.assertEqual(
+            detector.detect(),
+            resources.Resource({"service.name": "from-service-name"}),
+        )