chore(pymongo): service name override in pymongo (#10917)

This PR makes the following changes:
- Setting `config.pymongo['service']` did not override service name, due
to previously having a `Pin` overriding. This changes the `Pin` on the
MongoClient` to `None`
- We should use `ext_service` instead of `int_service` for pymongo 

## Checklist
- [x] PR author has checked that all the criteria below are met
- The PR description includes an overview of the change
- The PR description articulates the motivation for the change
- The change includes tests OR the PR description describes a testing
strategy
- The PR description notes risks associated with the change, if any
- Newly-added code is easy to change
- The change follows the [library release note
guidelines](https://ddtrace.readthedocs.io/en/stable/releasenotes.html)
- The change includes or references documentation updates if necessary
- Backport labels are set (if
[applicable](https://ddtrace.readthedocs.io/en/latest/contributing.html#backporting))

## Reviewer Checklist
- [x] Reviewer has checked that all the criteria below are met 
- Title is accurate
- All changes are related to the pull request's stated goal
- Avoids breaking
[API](https://ddtrace.readthedocs.io/en/stable/versioning.html#interfaces)
changes
- Testing strategy adequately addresses listed risks
- Newly-added code is easy to change
- Release note makes sense to a user of the library
- If necessary, author has acknowledged and discussed the performance
implications of this PR as reported in the benchmarks PR comment
- Backport labels are set in a manner that is consistent with the
[release branch maintenance
policy](https://ddtrace.readthedocs.io/en/latest/contributing.html#backporting)

ddtrace/contrib/internal/pymongo/client.py

@@ -10,10 +10,12 @@
 
 # project
 import ddtrace
+from ddtrace import Pin
 from ddtrace import config
 from ddtrace.constants import _ANALYTICS_SAMPLE_RATE_KEY
 from ddtrace.constants import SPAN_KIND
 from ddtrace.constants import SPAN_MEASURED_KEY
+from ddtrace.contrib import trace_utils
 from ddtrace.ext import SpanKind
 from ddtrace.ext import SpanTypes
 from ddtrace.ext import db
@@ -67,7 +69,7 @@ def __getddpin__(client):
     client.__getddpin__ = functools.partial(__getddpin__, client)
 
     # Set a pin on the traced mongo client
-    ddtrace.Pin(service=_DEFAULT_SERVICE).onto(client)
+    Pin(service=None).onto(client)
 
 
 # The function is exposed in the public API, but it is not used in the codebase.
@@ -128,7 +130,7 @@ def _datadog_trace_operation(operation, wrapped):
     span = pin.tracer.trace(
         schematize_database_operation("pymongo.cmd", database_provider="mongodb"),
         span_type=SpanTypes.MONGODB,
-        service=pin.service,
+        service=trace_utils.ext_service(pin, config.pymongo),
     )
 
     span.set_tag_str(COMPONENT, config.pymongo.integration_name)
@@ -251,7 +253,7 @@ def _trace_cmd(cmd, socket_instance, address):
     s = pin.tracer.trace(
         schematize_database_operation("pymongo.cmd", database_provider="mongodb"),
         span_type=SpanTypes.MONGODB,
-        service=pin.service,
+        service=trace_utils.ext_service(pin, config.pymongo),
     )
 
     s.set_tag_str(COMPONENT, config.pymongo.integration_name)

ddtrace/contrib/internal/pymongo/patch.py

@@ -16,6 +16,8 @@
 from ddtrace.internal.wrapping import unwrap as _u
 from ddtrace.internal.wrapping import wrap as _w
 
+from ....internal.schema import schematize_service_name
+
 # keep TracedMongoClient import to maintain backwards compatibility
 from .client import TracedMongoClient  # noqa: F401
 from .client import _trace_mongo_client_init
@@ -46,10 +48,7 @@
 _CHECKOUT_FN_NAME = "get_socket" if pymongo.version_tuple < (4, 5) else "checkout"
 
 
-config._add(
-    "pymongo",
-    dict(_default_service="pymongo"),
-)
+config._add("pymongo", dict(_default_service=schematize_service_name("pymongo")))
 
 
 def get_version():
@@ -119,7 +118,7 @@ def traced_get_socket(func, args, kwargs):
 
     with pin.tracer.trace(
         "pymongo.%s" % _CHECKOUT_FN_NAME,
-        service=trace_utils.int_service(pin, config.pymongo),
+        service=trace_utils.ext_service(pin, config.pymongo),
         span_type=SpanTypes.MONGODB,
     ) as span:
         span.set_tag_str(COMPONENT, config.pymongo.integration_name)

tests/contrib/pymongo/test.py

@@ -544,6 +544,27 @@ def test_user_specified_service_v0(self):
         assert len(spans) == 2
         assert spans[1].service != "mysvc"
 
+    @TracerTestCase.run_in_subprocess(env_overrides=dict())
+    def test_user_specified_service_default_override(self):
+        """
+        Override service name using config
+        """
+        from ddtrace import config
+        from ddtrace import patch
+
+        cfg = config.pymongo
+        cfg["service"] = "new-mongo"
+        patch(pymongo=True)
+        assert cfg.service == "new-mongo", f"service name is {cfg.service}"
+        tracer = DummyTracer()
+        client = pymongo.MongoClient(port=MONGO_CONFIG["port"])
+        Pin.get_from(client).clone(tracer=tracer).onto(client)
+
+        client["testdb"].drop_collection("whatever")
+        spans = tracer.pop()
+        assert spans
+        assert spans[0].service == "new-mongo", f"service name is {spans[0].service}"
+
     @TracerTestCase.run_in_subprocess(env_overrides=dict(DD_SERVICE="mysvc", DD_TRACE_SPAN_ATTRIBUTE_SCHEMA="v1"))
     def test_user_specified_service_v1(self):
         """
@@ -563,6 +584,20 @@ def test_user_specified_service_v1(self):
         assert len(spans) == 2
         assert spans[1].service == "mysvc"
 
+    @TracerTestCase.run_in_subprocess(env_overrides=dict())
+    def test_unspecified_service_v0(self):
+        """
+        v0: When a user does not specify a service for the app
+            The pymongo integration should use pymongo.
+        """
+        tracer = DummyTracer()
+        client = pymongo.MongoClient(port=MONGO_CONFIG["port"])
+        Pin.get_from(client).clone(tracer=tracer).onto(client)
+        client["testdb"].drop_collection("whatever")
+        spans = tracer.pop()
+        assert len(spans) == 2
+        assert spans[1].service == "pymongo"
+
     @TracerTestCase.run_in_subprocess(
         env_overrides=dict(DD_PYMONGO_SERVICE="mypymongo", DD_TRACE_SPAN_ATTRIBUTE_SCHEMA="v0")
     )