Log to a file and make it visible via the API

src/openflexure_microscope_server/logging.py

@@ -0,0 +1,38 @@
+import logging
+from logging.handlers import RotatingFileHandler
+import os
+
+from fastapi.responses import FileResponse, PlainTextResponse
+
+OFM_LOG_FOLDER =  "/var/openflexure/log/"
+OFM_LOG_FILE = os.path.join(OFM_LOG_FOLDER, "openflexure-microscope-server.log")
+
+def configure_logging():
+    root_logger = logging.getLogger()
+    root_logger.setLevel(logging.INFO)
+    try:
+        if not os.path.exists(OFM_LOG_FOLDER):
+            os.makedirs(OFM_LOG_FOLDER)
+        handler = RotatingFileHandler(
+            filename = OFM_LOG_FILE,
+            mode = "a",
+            maxBytes = 1000000,
+            backupCount = 10,
+        )
+        handler.setFormatter(
+            logging.Formatter(
+                "[%(asctime)s] [%(levelname)s] %(message)s"
+            )
+        )
+        root_logger.addHandler(handler)
+    except PermissionError as e:
+        logging.warning(f"Cannot create log file at {OFM_LOG_FILE}: {e}")
+    logging.info("")
+    logging.info("****************************************************")
+    logging.info("OFM server root logger has been set up at INFO level")
+    logging.info("****************************************************")
+
+
+def retrieve_log() -> PlainTextResponse:
+    """The most recent 1Mb of logs from the server"""
+    return FileResponse(OFM_LOG_FILE, media_type=PlainTextResponse.media_type)

src/openflexure_microscope_server/server.py

@@ -14,11 +14,9 @@ from .things.camera_stage_mapping import CameraStageMapper
 from .things.system_control import SystemControlThing
 from .things.settings_manager import SettingsManager
 from .serve_static_files import add_static_files
+from .logging import configure_logging, retrieve_log
 
-root_logger = logging.getLogger()
-root_logger.setLevel(logging.INFO)
-root_logger.info("This is a message from OFM server via root_logger")
-logging.info("This is another message via logging.info")
+configure_logging()
 
 thing_server = ThingServer()
 thing_server.add_thing(StreamingPiCamera2(), "/camera/")
@@ -32,6 +30,9 @@ try:
 except RuntimeError:
     print("Failed to add static files - you will have to do without them!")
 
+# Add an endpoint to get the log
+thing_server.app.get("/log/")(retrieve_log)
+
 
 app = thing_server.app