Add public flask.g.request_id when not set (fix #50) (#51)

Author: g-k

docs/flask.rst

@@ -25,6 +25,9 @@ Flask based projects that want to follow the Dockerflow specs:
 
   - Hooks to add custom Dockerflow checks.
 
+- Adds ``request_id`` to the `flask.g`_ application namespace when it isn't already set
+
+.. _`flask.g`: https://flask.palletsprojects.com/en/1.1.x/api/#flask.g
 .. _`mozlog`: https://github.com/mozilla-services/Dockerflow/blob/master/docs/mozlog.md
 .. _`request.summary`: https://github.com/mozilla-services/Dockerflow/blob/master/docs/mozlog.md#application-request-summary-type-requestsummary
 

src/dockerflow/flask/app.py

@@ -204,6 +204,8 @@ def _before_request(self):
         The before_request callback.
         """
         g._request_id = str(uuid.uuid4())
+        if not hasattr(g, "request_id"):
+            g.request_id = g._request_id
         g._start_timestamp = time.time()
 
     def _after_request(self, response):

tests/flask/test_flask.py

@@ -225,6 +225,7 @@ def test_request_summary(caplog, dockerflow, app):
     with app.test_client() as test_client:
         test_client.get("/", headers=headers)
         assert getattr(g, "_request_id") is not None
+        assert getattr(g, "request_id") is not None
         assert isinstance(getattr(g, "_start_timestamp"), float)
 
         assert len(caplog.records) == 1
@@ -233,6 +234,19 @@ def test_request_summary(caplog, dockerflow, app):
             assert getattr(request, "uid", None) is None
 
 
+def test_preserves_existing_request_id(dockerflow, app):
+    with app.test_client() as test_client:
+
+        def set_dummy_request_id():
+            g.request_id = "predefined-request-id"
+
+        app.before_request(set_dummy_request_id)
+
+        test_client.get("/", headers=headers)
+        assert getattr(g, "_request_id") is not None
+        assert getattr(g, "request_id") != getattr(g, "_request_id")
+
+
 def assert_user(app, caplog, user, callback):
     with app.test_request_context("/", headers=headers):
         assert has_request_context()