chore(python_server): support optional metrics

CHANGELOG.md

@@ -2,6 +2,8 @@
 
 ## Unreleased
 
+- Python server: Support optional metrics ([#828](https://github.com/mozilla/glean_parser/pull/828))
+
 ## 18.2.0
 
 - New lint: Warn against event metrics on the `metrics` or `baseline` ping ([#823](https://github.com/mozilla/glean_parser/pull/823))

glean_parser/templates/python_server.jinja2

@@ -35,29 +35,34 @@ class {{ ping|camelize }}ServerEventLogger:
 
     def record(
         self,
-        user_agent: str,
-        ip_address: str,
+        user_agent: str | None = None,
+        ip_address: str | None = None,
         {% for metric_type, metrics in metrics_by_type.items() %}
         {% if metric_type != 'event' %}
         {% for metric in metrics %}
-        {{ metric.category }}_{{ metric.name }}: {{ metric.type|py_metric_type }},
+        {{ metric.category }}_{{ metric.name }}: {{ metric.type|py_metric_type }} | None = None,
         {% endfor %}
         {% endif %}
         {% endfor %}
-        events: list[dict[str, Any]]
+        events: list[dict[str, Any]] | None = None,
     ) -> None:
         now = datetime.now(timezone.utc)
         timestamp = now.isoformat()
+        events = [] if events is None else events
         for event in events:
             event["timestamp"] = int(1000.0 * now.timestamp())  # Milliseconds since epoch
         event_payload = {
             "metrics": {
                 {% for metric_type, metrics in metrics_by_type.items() %}
                 {% if metric_type != 'event' %}
                 "{{ metric_type }}": {
-                    {% for metric in metrics %}
-                    "{{ metric.category }}.{{ metric.name }}": {{ metric.category }}_{{ metric.name }},
-                    {% endfor %}
+                    key: value
+                    for key, value in [
+                        {% for metric in metrics %}
+                        ("{{ metric.category }}.{{ metric.name }}", {{ metric.category }}_{{ metric.name }}),
+                        {% endfor %}
+                    ]
+                    if value is not None
                 },
                 {% endif %}
                 {% endfor %}
@@ -117,17 +122,17 @@ class {{ ping|camelize }}ServerEventLogger:
     {% for event in metrics_by_type["event"] %}
     def {{ event|record_event_function_name }}(
         self,
-        user_agent: str,
-        ip_address: str,
+        user_agent: str | None = None,
+        ip_address: str | None = None,
         {% for metric_type, metrics in metrics_by_type.items() %}
         {% if metric_type != 'event' %}
         {% for metric in metrics %}
-        {{ metric.category }}_{{ metric.name }}: {{ metric.type|py_metric_type }},
+        {{ metric.category }}_{{ metric.name }}: {{ metric.type|py_metric_type }} | None = None,
         {% endfor %}
         {% endif %}
         {% endfor %}
         {% for extra, metadata in event.extra_keys.items() %}
-        {{ extra }}: {{ metadata.type|py_metric_type }},
+        {{ extra }}: {{ metadata.type|py_metric_type }} | None = None,
         {% endfor %}
     ) -> None:
         """
@@ -156,9 +161,13 @@ class {{ ping|camelize }}ServerEventLogger:
             "name": "{{ event.name }}",
             {% if event.extra_keys %}
             "extra": {
-                {% for extra, metadata in event.extra_keys.items() %}
-                "{{ extra }}": str({{ extra }}){% if 'bool' == metadata.type|py_metric_type %}.lower(){% endif %},
-                {% endfor %}
+                key: value
+                for key, value in [
+                    {% for extra, metadata in event.extra_keys.items() %}
+                    ("{{ extra }}", str({{ extra }}){% if 'bool' == metadata.type|py_metric_type %}.lower(){% endif %}),
+                    {% endfor %}
+                ]
+                if value is not None
             },
             {% endif %}
         }

tests/test-py/test.py

@@ -15,3 +15,7 @@
     object_state="some_object_state",
     linking=True,
 )
+
+logger.record_backend_object_update()
+
+logger.record()

tests/test_python_server.py

@@ -52,29 +52,30 @@ def test_logging(tmp_path):
         "utf-8"
     )
 
-    logged_output = json.loads(logged_output)
-    fields = logged_output["Fields"]
-    payload = fields["payload"]
-
-    # validate that ping envelope contains all the required fields
-    assert "glean-server-event" == logged_output["Type"]
-    assert "accounts_backend" == fields["document_namespace"]
-    assert "events" == fields["document_type"]
-    assert "1" == fields["document_version"]
-    assert "Mozilla/5.0 ..." == fields["user_agent"]
-
-    schema_url = (
-        "https://raw.githubusercontent.com/mozilla-services/"
-        "mozilla-pipeline-schemas/main/"
-        "schemas/glean/glean/glean.1.schema.json"
-    )
-
-    # validate that ping payload is valid against glean schema
-    input = io.StringIO(payload)
-    output = io.StringIO()
-    assert validate_ping.validate_ping(input, output, schema_url=schema_url) == 0, (
-        output.getvalue()
-    )
+    for log_line in logged_output.splitlines():
+        json_line = json.loads(log_line)
+        fields = json_line["Fields"]
+        payload = fields["payload"]
+
+        # validate that ping envelope contains all the required fields
+        assert "glean-server-event" == json_line["Type"]
+        assert "accounts_backend" == fields["document_namespace"]
+        assert "events" == fields["document_type"]
+        assert "1" == fields["document_version"]
+        assert fields["user_agent"] in ("Mozilla/5.0 ...", None)
+
+        schema_url = (
+            "https://raw.githubusercontent.com/mozilla-services/"
+            "mozilla-pipeline-schemas/main/"
+            "schemas/glean/glean/glean.1.schema.json"
+        )
+
+        # validate that ping payload is valid against glean schema
+        input = io.StringIO(payload)
+        output = io.StringIO()
+        assert validate_ping.validate_ping(input, output, schema_url=schema_url) == 0, (
+            output.getvalue()
+        )
 
 
 def test_parser_python_server_metrics_unsupported_type(tmp_path, capsys):