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"""Application base class.
"""
import argparse
import logging
import logging.handlers
import os
import sys
LOG = logging.getLogger(__name__)
class App(object):
"""Application base class.
"""
NAME = os.path.splitext(os.path.basename(sys.argv[0]))[0]
CONSOLE_MESSAGE_FORMAT = '%(message)s'
LOG_FILE_MESSAGE_FORMAT = '[%(asctime)s] %(levelname)-8s %(name)s %(message)s'
DEFAULT_VERBOSE_LEVEL = 1
def __init__(self, description, version, command_manager,
stdin=None, stdout=None, stderr=None):
"""Initialize the application.
:param description: One liner explaining the program purpose
:param version: String containing the application version number
:param command_manager: A CommandManager instance
:param stdin: Standard input stream
:param stdout: Standard output stream
:param stderr: Standard error output stream
"""
self.command_manager = command_manager
self.stdin = stdin or sys.stdin
self.stdout = stdout or sys.stdout
self.stderr = stderr or sys.stderr
self.parser = self.build_option_parser(description, version)
def build_option_parser(self, description, version):
"""Return an argparse option parser for this application.
Subclasses may override this method to extend
the parser with more global options.
"""
parser = argparse.ArgumentParser(
description=description,
add_help=False,
)
parser.add_argument(
'--version',
action='version',
version='%(prog)s {}'.format(version),
)
parser.add_argument(
'-v', '--verbose',
action='count',
dest='verbose_level',
default=self.DEFAULT_VERBOSE_LEVEL,
help='Increase verbosity of output. Can be repeated.',
)
parser.add_argument(
'-q', '--quiet',
action='store_const',
dest='verbose_level',
const=0,
help='suppress output except warnings and errors',
)
parser.add_argument(
'-h', '--help',
action='help',
help="show this help message and exit",
)
parser.add_argument(
'--debug',
default=False,
action='store_true',
help='show tracebacks on errors',
)
return parser
def show_verbose_help(self, *args):
"""Displays the normal syntax info and a list of available subcommands.
"""
self.parser.print_help()
print('')
print('Commands:')
for name, ep in sorted(self.command_manager):
factory = ep.load()
cmd = factory(self, None)
print(' %-13s %s' % (name, cmd.get_description()))
sys.exit(0)
def configure_logging(self):
"""Create logging handlers for any log output.
"""
root_logger = logging.getLogger('')
# Set up logging to a file
root_logger.setLevel(logging.DEBUG)
file_handler = logging.handlers.RotatingFileHandler(
self.NAME + '.log',
maxBytes=10240,
backupCount=1,
)
formatter = logging.Formatter(self.LOG_FILE_MESSAGE_FORMAT)
file_handler.setFormatter(formatter)
root_logger.addHandler(file_handler)
# Send higher-level messages to the console via stderr
console = logging.StreamHandler()
console_level = {0: logging.WARNING,
1: logging.INFO,
2: logging.DEBUG,
}.get(self.options.verbose_level, logging.DEBUG)
console.setLevel(console_level)
formatter = logging.Formatter(self.CONSOLE_MESSAGE_FORMAT)
console.setFormatter(formatter)
root_logger.addHandler(console)
return
def prepare_to_run_command(self, cmd):
"""Perform any preliminary work needed to run a command.
"""
return
def clean_up(self, cmd, result, err):
"""Hook run after a command is done to shutdown the app.
"""
return
def run(self, argv):
"""Equivalent to the main program for the application.
"""
if not argv:
argv = ['-h']
self.options, remainder = self.parser.parse_known_args(argv)
self.configure_logging()
cmd_factory, cmd_name, sub_argv = self.command_manager.find_command(remainder)
cmd = cmd_factory(self, self.options)
err = None
result = 1
try:
self.prepare_to_run_command(cmd)
cmd_parser = cmd.get_parser(' '.join([self.NAME, cmd_name]))
parsed_args = cmd_parser.parse_args(sub_argv)
result = cmd.run(parsed_args)
except Exception as err:
if self.options.debug:
LOG.exception(err)
raise
LOG.error('ERROR: %s', err)
finally:
try:
self.clean_up(cmd, result, err)
except Exception as err2:
if self.options.debug:
LOG.exception(err2)
else:
LOG.error('Could not clean up: %s', err2)
return result
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