Stop reporting uvicorn.error in log file unless log it is an error

src/openflexure_microscope_server/logging.py

@@ -53,7 +53,7 @@ def configure_logging(log_folder):
             backupCount=10,
         )
         format_str = "[%(asctime)s] [%(levelname)s] <%(name)s> %(message)s"
-        handler.setFormatter(logging.Formatter(format_str))
+        handler.setFormatter(OFMLogFileFormatter(format_str))
         handler.addFilter(UvicornAccessFilter())
         root_logger.addHandler(handler)
 
@@ -100,6 +100,25 @@ def retrieve_log_from_file() -> PlainTextResponse:
         ) from e
 
 
+class OFMLogFileFormatter(logging.Formatter):
+    """The formatter used for the OpenFlexure Microscope Server log file."""
+
+    def format(self, record):
+        """Adjust the logging formatting for uvicorn logs.
+
+        Any ``uvicorn.error`` logs that are at a lower
+
+        uvicorn has two loggers. Each API access is ``uvicorn.access`` which we filter
+        due to the noise the other is ``uvicorn.error`` for more important messages.
+        However, ``uvicorn.error`` is used for expected messages that are not errors,
+        such as server start up. This can lead to people erroneously thinking that
+        there is an error with their miroscope.
+        """
+        if record.name == "uvicorn.error" and record.levelno < logging.ERROR:
+            record.name = "uvicorn"
+        return super().format(record)
+
+
 class OFMHandler(logging.Handler):
     """A logging.Handler that stores the most recent logs for access by the server."""
 

tests/test_logging.py

@@ -155,3 +155,36 @@ def test_server_response_with_no_log_dir():
     with pytest.raises(HTTPException) as excinfo:
         ofm_logging.retrieve_log_from_file()
     assert excinfo.value.status_code == 500
+
+
+FAKE_UVICORN_LOGGER = logging.getLogger("uvicorn.error")
+
+
+@pytest.mark.parametrize(
+    "log_command, names_in_log, names_not_in_log",
+    [
+        [FAKE_UVICORN_LOGGER.debug, [], ["<uvicorn>", "<uvicorn.error>"]],
+        [FAKE_UVICORN_LOGGER.info, ["<uvicorn>"], ["<uvicorn.error>"]],
+        [FAKE_UVICORN_LOGGER.warning, ["<uvicorn>"], ["<uvicorn.error>"]],
+        [FAKE_UVICORN_LOGGER.error, ["<uvicorn.error>"], ["<uvicorn>"]],
+        [FAKE_UVICORN_LOGGER.exception, ["<uvicorn.error>"], ["<uvicorn>"]],
+    ],
+)
+def test_uvicorn_error_only_says_error_on_error(
+    log_command, names_in_log, names_not_in_log
+):
+    """Check that an HTTP exception is raised if the log file cannot be accessed.
+
+    Parametrised to check: debug doesn't log, info and warning log as <uvicorn>, and
+    error logs as <uvicorn.error>.
+    """
+    ofm_logging.OFM_HANDLER = ofm_logging.OFMHandler()
+    with tempfile.TemporaryDirectory() as tmpdir:
+        ofm_logging.configure_logging(tmpdir)
+        log_command("Mockedy mock mock!")
+        with open(ofm_logging.OFM_LOG_FILE, "r", encoding="utf-8") as log_file:
+            log_txt = log_file.read()
+        for name in names_in_log:
+            assert name in log_txt
+        for name in names_not_in_log:
+            assert name not in log_txt