Merge pull request #37 from MycroftAI/logging-setup

Logging setup

.gitignore

@@ -8,6 +8,9 @@
 # dependencies
 **/node_modules
 
+# python notebooks
+*.ipynb
+
 # IDEs and editors
 **/.idea
 .project

shared/selene/util/log.py

@@ -0,0 +1,85 @@
+"""Standardize logger setup.
+
+Standardizations:
+    * applications logs go into a /var/log/mycroft/<application_name>.log file
+        be sure that whatever host you are logging on has the /var/log/mycroft
+        directory, which is owned by the application user.
+    * log files contain all log messages of all levels by default.  this can be
+        very handy to debug issues with an application but won't clog up a
+        console log viewer
+    * log files will be rotated on a daily basis at midnight.  this makes logs
+        easier to manage and use, especially when debug messages are included
+    * log messages at warning level and above will be streamed to the console
+        by default.  this will bring attention to any issues or potential
+        issues without clogging up the console with a potentially massive
+        amount of log messages.
+    * log messages will be formatted as such:
+        YYYY-MM-DD HH:MM:SS,FFF | LEVEL | PID | LOGGER | LOG MESSAGE
+
+Any of the above standardizations can be overridden by changing an instance
+attribute on the LoggingConfig class.  In general, this should not be done.
+Possible exceptions include increasing verbosity for debugging.
+"""
+
+from os import path
+from logging import (
+    DEBUG,
+    Formatter,
+    getLogger,
+    handlers,
+    StreamHandler,
+    WARN
+)
+
+
+class LoggingConfig(object):
+    """Configure a logger with a daily log file and a console log"""
+    def __init__(self, log_file_name):
+        self.logger = getLogger()
+        self.file_log_level = DEBUG
+        self.console_log_level = WARN
+        self.log_file_path = path.join('/var/log/mycroft', log_file_name)
+        self.log_msg_formatter = Formatter(
+            '{asctime} | {levelname:8} | {process:5} | {name} | {message}',
+            style='{'
+        )
+
+    def _define_file_handler(self):
+        """build a file handler"""
+        handler = handlers.TimedRotatingFileHandler(
+            filename=self.log_file_path,
+            when='midnight',
+            utc=True
+        )
+        handler.setLevel(self.file_log_level)
+        handler.setFormatter(self.log_msg_formatter)
+
+        return handler
+
+    def _define_console_handler(self):
+        """build a console, or stream, handler"""
+        handler = StreamHandler()
+        handler.setLevel(self.console_log_level)
+        handler.setFormatter(self.log_msg_formatter)
+
+        return handler
+
+    def configure(self):
+        """Put it all together"""
+        file_handler = self._define_file_handler()
+        console_handler = self._define_console_handler()
+        self.logger.addHandler(file_handler)
+        self.logger.addHandler(console_handler)
+
+
+def configure_logger(log_file_name: str, logger_name: str = None):
+    """helper function that returns a logger using the base config"""
+    logging_config = LoggingConfig(log_file_name)
+    logging_config.configure()
+
+    if logger_name is None:
+        logger = getLogger()
+    else:
+        logger = getLogger(logger_name)
+
+    return logger