fix(remoteconfig): handle process fork inside remote config client [backport 1.17] (#6778)

Backport de2675a from #6172 to 1.17.

When a process fork, the remote config client need to have a new
runtime-id and a client-id.

However, the state of the configuration should remain the same.

## Checklist

- [x] Change(s) are motivated and described in the PR description.
- [x] Testing strategy is described if automated tests are not included
in the PR.
- [x] Risk is outlined (performance impact, potential for breakage,
maintainability, etc).
- [x] Change is maintainable (easy to change, telemetry, documentation).
- [x] [Library release note
guidelines](https://ddtrace.readthedocs.io/en/stable/releasenotes.html)
are followed. If no release note is required, add label
`changelog/no-changelog`.
- [x] Documentation is included (in-code, generated user docs, [public
corp docs](https://github.com/DataDog/documentation/)).
- [x] Backport labels are set (if
[applicable](../docs/contributing.rst#release-branch-maintenance))

## Reviewer Checklist

- [x] Title is accurate.
- [x] No unnecessary changes are introduced.
- [x] Description motivates each change.
- [x] Avoids breaking
[API](https://ddtrace.readthedocs.io/en/stable/versioning.html#interfaces)
changes unless absolutely necessary.
- [x] Testing strategy adequately addresses listed risk(s).
- [x] Change is maintainable (easy to change, telemetry, documentation).
- [x] Release note makes sense to a user of the library.
- [x] Reviewer has explicitly acknowledged and discussed the performance
implications of this PR as reported in the benchmarks PR comment.
- [x] Backport labels are set in a manner that is consistent with the
[release branch maintenance
policy](../docs/contributing.rst#release-branch-maintenance)

Co-authored-by: Idan Shatz <[email protected]>
Co-authored-by: Munir Abdinur <[email protected]>

Author: 3 people

ddtrace/internal/remoteconfig/client.py

@@ -216,6 +216,11 @@ def base64_to_struct(val, cls):
         self._last_error = None  # type: Optional[str]
         self._backend_state = None  # type: Optional[str]
 
+    def renew_id(self):
+        # called after the process is forked to declare a new id
+        self.id = str(uuid.uuid4())
+        self._client_tracer["runtime_id"] = runtime.get_runtime_id()
+
     def register_product(self, product_name, pubsub_instance=None):
         # type: (str, Optional[PubSub]) -> None
         if pubsub_instance is not None:

ddtrace/internal/remoteconfig/worker.py

@@ -102,6 +102,7 @@ def start_subscribers(self):
         """Subscribers need to be restarted when application forks"""
         self._enable = False
         log.debug("[%s][P: %s] Remote Config Poller fork. Starting Pubsub services", os.getpid(), os.getppid())
+        self._client.renew_id()
         for pubsub in self._client.get_pubsubs():
             pubsub.restart_subscriber()
 

tests/internal/remoteconfig/test_remoteconfig.py

@@ -159,9 +159,22 @@ def test_remote_config_forksafe():
         parent_worker = remoteconfig_poller
         assert parent_worker.status == ServiceStatus.RUNNING
 
+        client_id = remoteconfig_poller._client.id
+        runtime_id = remoteconfig_poller._client._client_tracer["runtime_id"]
+
+        parent_payload = remoteconfig_poller._client._build_payload(None)
+
+        assert client_id == parent_payload["client"]["id"]
+        assert runtime_id == parent_payload["client"]["client_tracer"]["runtime_id"]
+
         if os.fork() == 0:
             assert remoteconfig_poller.status == ServiceStatus.RUNNING
             assert remoteconfig_poller._worker is not parent_worker
+
+            child_payload = remoteconfig_poller._client._build_payload(None)
+
+            assert client_id != child_payload["client"]["id"]
+            assert runtime_id != child_payload["client"]["client_tracer"]["runtime_id"]
             exit(0)