logging: Implement colors for console messages

Reviewed-by: James Valleroy <jvalleroy@mailbox.org>

plinth/log.py

@@ -27,6 +27,53 @@ import cherrypy
 from . import cfg
 
 
+class ColoredFormatter(logging.Formatter):
+    """Print parts of log message in color."""
+    codes = {
+        'black': 30,
+        'red': 31,
+        'green': 32,
+        'yellow': 33,
+        'blue': 34,
+        'magenta': 35,
+        'cyan': 36,
+        'white': 37,
+        'bright_black': 90,
+        'bright_red': 91,
+        'bright_green': 92,
+        'bright_yellow': 93,
+        'bright_blue': 94,
+        'bright_magenta': 95,
+        'bright_cyan': 96,
+        'bright_white': 97
+    }
+
+    level_colors = {
+        'DEBUG': 'bright_black',
+        'INFO': 'bright_white',
+        'WARNING': 'bright_yellow',
+        'ERROR': 'red',
+        'CRITICAL': 'bright_red'
+    }
+
+    def wrap_color(self, string, color=None):
+        """Return a string wrapped in terminal escape codes for coloring."""
+        if not color:
+            return string
+
+        return '\x1b[{}m'.format(self.codes[color]) + string + '\x1b[0m'
+
+    def format(self, record):
+        """Format a record into a string"""
+        record_name = '{:<20}'.format(record.name)
+        record.colored_name = self.wrap_color(record_name, 'bright_blue')
+
+        level_color = self.level_colors.get(record.levelname, None)
+        level_name = '{:>8}'.format(record.levelname)
+        record.colored_levelname = self.wrap_color(level_name, level_color)
+        return super().format(record)
+
+
 def init():
     """Setup the logging framework."""
     # Remove default handlers and let the log message propagate to root logger.
@@ -59,15 +106,16 @@ def get_configuration():
         'version': 1,
         'disable_existing_loggers': False,
         'formatters': {
-            'default': {
-                'format':
-                    '%(name)-14s %(levelname)-8s %(message)s',
+            'color': {
+                '()': 'plinth.log.ColoredFormatter',
+                'format': '{colored_levelname} {colored_name} {message}',
+                'style': '{'
             }
         },
         'handlers': {
             'console': {
                 'class': 'logging.StreamHandler',
-                'formatter': 'default'
+                'formatter': 'color'
             }
         },
         'root': {