[rpi] Add log file rotation

so that log file doesn't grow infinitely

tools/rpi/ahoy.yml.example

@@ -7,6 +7,8 @@ ahoy:
     filename: 'hoymiles.log'
     # DEBUG, INFO, WARNING, ERROR, FATAL
     level: 'INFO'
+    max_log_filesize: 1000000
+    max_log_files: 1
 
   sunset:
     disabled: false

tools/rpi/hoymiles/__main__.py

@@ -19,6 +19,7 @@ import yaml
 from yaml.loader import SafeLoader
 import hoymiles
 import logging
+from logging.handlers import RotatingFileHandler
 
 ################################################################################
 """ Signal Handler """
@@ -298,6 +299,8 @@ def init_logging(ahoy_config):
     log_config = ahoy_config.get('logging')
     fn = 'hoymiles.log'
     lvl = logging.ERROR
+    max_log_filesize = 1000000
+    max_log_files = 1
     if log_config:
         fn = log_config.get('filename', fn)
         level = log_config.get('level', 'ERROR')
@@ -311,9 +314,11 @@ def init_logging(ahoy_config):
             lvl = logging.ERROR
         elif level == 'FATAL':
             lvl = logging.FATAL
+        max_log_filesize  = log_config.get('max_log_filesize', max_log_filesize)
+        max_log_files = log_config.get('max_log_files', max_log_files)
     if hoymiles.HOYMILES_TRANSACTION_LOGGING:
        lvl = logging.DEBUG
-    logging.basicConfig(filename=fn, format='%(asctime)s %(levelname)s: %(message)s', datefmt='%Y-%m-%d %H:%M:%S', level=lvl)
+    logging.basicConfig(handlers=[RotatingFileHandler(fn, maxBytes=max_log_filesize, backupCount=max_log_files)], format='%(asctime)s %(levelname)s: %(message)s', datefmt='%Y-%m-%d %H:%M:%S', level=lvl)
     dtu_name = ahoy_config.get('dtu',{}).get('name','hoymiles-dtu')
     logging.info(f'start logging for {dtu_name} with level: {logging.root.level}')