cloudbridge/cloudbridge/__init__.py

"""Library setup."""
import logging

# Current version of the library
__version__ = '3.0.0'


def get_version():
    """
    Return a string with the current version of the library.

    :rtype: ``string``
    :return:  Library version (e.g., "0.1.0").
    """
    return __version__


def init_logging():
    """
    Initialize logging for testing.

    Temporary workaround for build timeouts by enabling logging to
    stdout so that Travis doesn't think the build has hung.
    """
    set_stream_logger(__name__, level=logging.DEBUG)


class NullHandler(logging.Handler):
    """A null handler for the logger."""

    def emit(self, record):
        """Don't emit a log."""
        pass


TRACE = 5  # Lower than debug which is 10


class CBLogger(logging.Logger):
    """
    A custom logger, adds logging level below debug.

    Add a ``trace`` log level, numeric value 5: ``log.trace("Log message")``
    """

    def trace(self, msg, *args, **kwargs):
        """Add ``trace`` log level."""
        self.log(TRACE, msg, *args, **kwargs)


# By default, do not force any logging by the library. If you want to see the
# log messages in your scripts, add the following to the top of your script:
#   import cloudbridge
#   cloudbridge.set_stream_logger(__name__)
#   OR
#   cloudbridge.set_file_logger(__name__, '/tmp/log')
default_format_string = "%(asctime)s [%(levelname)s] %(name)s: %(message)s"
logging.setLoggerClass(CBLogger)
logging.addLevelName(TRACE, "TRACE")
log = logging.getLogger('cloudbridge')
log.addHandler(NullHandler())

# Convenience functions to set logging to a particular file or stream
# To enable either of these by default within CloudBridge, add the following
# at the top of a CloudBridge module:
#   import cloudbridge
#   cloudbridge.set_stream_logger(__name__)
#   OR
#   cloudbridge.set_file_logger(__name__, '/tmp/log')


def set_stream_logger(name, level=TRACE, format_string=None):
    """A convenience method to set the global logger to stream."""
    global log
    if not format_string:
        format_string = default_format_string
    logger = logging.getLogger(name)
    logger.setLevel(level)
    fh = logging.StreamHandler()
    fh.setLevel(level)
    formatter = logging.Formatter(format_string)
    fh.setFormatter(formatter)
    logger.addHandler(fh)
    log = logger


def set_file_logger(name, filepath, level=logging.INFO, format_string=None):
    """A convenience method to set the global logger to a file."""
    global log
    if not format_string:
        format_string = default_format_string
    logger = logging.getLogger(name)
    logger.setLevel(level)
    fh = logging.FileHandler(filepath)
    fh.setLevel(level)
    formatter = logging.Formatter(format_string)
    fh.setFormatter(formatter)
    logger.addHandler(fh)
    log = logger