chore(python_server): replace print with sys.stdout.write (#820)

* chore(python_server): replace print with sys.stdout.write

because print writes the ping and newline separately, which increases the chances of something else, like another ping, getting printed between them

* Add changelog entry

---------

Co-authored-by: Arkadiusz Komarzewski <[email protected]>

Author: relud

CHANGELOG.md

@@ -2,6 +2,8 @@
 
 ## Unreleased
 
+- Python server: Fix logging mechanism ([#820](https://github.com/mozilla/glean_parser/pull/820))
+
 ## 18.1.0
 
 - Python server: Support sending custom pings without events ([#817](https://github.com/mozilla/glean_parser/pull/817))

glean_parser/templates/python_server.jinja2

@@ -12,6 +12,7 @@ from datetime import datetime, timezone
 from typing import Any
 from uuid import uuid4
 import json
+import sys
 
 GLEAN_EVENT_MOZLOG_TYPE = "glean-server-event"
 
@@ -111,7 +112,7 @@ class {{ ping|camelize }}ServerEventLogger:
         }
         ping_envelope_serialized = json.dumps(ping_envelope)
 
-        print(ping_envelope_serialized)
+        sys.stdout.write(f"{ping_envelope_serialized}\n")
 
     {% for event in metrics_by_type["event"] %}
     def {{ event|record_event_function_name }}(
@@ -132,7 +133,7 @@ class {{ ping|camelize }}ServerEventLogger:
         """
         Record and submit a {{ event.category }}_{{ event.name }} event:
         {{ event.description|clean_string }}
-        Event is logged to STDOUT via `print`.
+        Event is logged to STDOUT via `sys.stdout.write`.
 
         :param str user_agent: The user agent.
         :param str ip_address: The IP address. Will be used to decode Geo information