Handling Logging with Glusto¶

Default Logging¶

By default, a logging object (glustolog) is setup by Glusto. It writes to /tmp/glusto.log

The glustolog object is designed for use by Glusto itself. If you need a log that is independent of the events logged by Glusto, you can create a new log object for use in your scripts.

Setting up Logging¶

To create a new logging object, use the create_log command:

>>> mylog = g.create_log(name='mylog', filename='/tmp/my.log')

The default severity level is INFO.

To create a logging object with a severity level other than the default:

>>> mylog = g.create_log(name='mylog', filename='/tmp/my.log', level='WARNING')

The options are INFO, WARNING, ERROR, CRITICAL, and DEBUG

Sending a Log Event¶

To write a message to a log, use the standard Python logging methods with your log object.

An example sending a warning to mylog:

>>> mylog.warning('this is a test to my log')
>>> g.show_file('/tmp/my.log')
2016-07-10 09:07:11,591 WARNING (<module>) this is a test to my log

Available options are:

<log>.debug
<log>.info
<log>.error
<log>.warning
<log>.critical

Sending Log Events to Multiple Logfiles¶

If you need to log to multiple files at the same time, you can add additional log handlers to an existing log object.

To add an additional logfile to an existing log object:

>>> g.add_log(g.mylog, filename='/tmp/my_other.log', level='CRITICAL')

If ‘STDOUT’ is passed as the filename, a log will be added that prints to stdout.

>>> g.add_log(g.mylog, filename='STDOUT')
>>> g.mylog.info('This is a test log entry to stdout.')
2016-06-05 10:27:24,175 INFO (<module>) This is a test log entry to stdout.

Show the Logfiles Attached to a Specific Logger¶

To show a list of the logfiles attached to a logger, use the show_logs() command.

>>> g.show_logs(g.mylog)
Log:  mylog
- mylog1: /tmp/my.log (WARNING)
- mylog2: /tmp/my_other.log (CRITICAL)

Removing a Log¶

If a logfile is no longer needed, remove the logfile from the logger with the remove_log() command.

>>> g.show_logs(g.mylog)
Log: mylog
- mylog1: /tmp/my.log
- mylog2: sys.stdout
>>> g.remove_log(g.mylog, 'mylog1')

>>> g.show_logs(g.mylog)
Log: mylog
- mylog1: /tmp/my.log

To remove all logfiles from a logger, use the remove_log command without passing a name.

>>> g.remove_log(g.mylog)

Changing the Level of an Existing Log Handler¶

To change the level of an existing log, use the set_log_level() method.

>>> g.show_logs(g.log)
Log:  glustolog
- glustolog1: /tmp/glusto.log (DEBUG)
- glustolog2: /tmp/testtrunc.log (INFO)

>>> g.set_log_level('glustolog', 'glustolog2', 'WARNING')

>>> g.show_logs(g.log)
Log:  glustolog
- glustolog1: /tmp/glusto.log (DEBUG)
- glustolog2: /tmp/testtrunc.log (WARNING)

Changing the Filename of an Existing Log Handler¶

To change the level of an existing log, use the set_log_filename() method.

>>> g.show_logs(g.log)
Log:  glustolog
- glustolog1: /tmp/glusto.log (DEBUG)
- glustolog2: /tmp/testtrunc.log (INFO)

>>> g.set_log_filename('glustolog', 'glustolog2', '/tmp/my.log')

>>> g.show_logs(g.log)
Log:  glustolog
- glustolog1: /tmp/glusto.log (DEBUG)
- glustolog2: /tmp/my.log (WARNING)

Clearing a Log¶

To empty a logfile, use the clear_log() method.

>>> g.show_logs(g.log)
Log:  glustolog
- glustolog1: /tmp/glusto.log (DEBUG)
- glustolog2: /tmp/testtrunc.log (INFO)
>>> g.clear_log('glustolog', 'glustolog2')

Temporarily Disable Logging¶

There might be times when suspending logging at a certain level is necessary. For example, if a particular function tends to spam the log.

To suspend logging at a specific level, use the disable_log_levels() method.

>>> g.disable_log_levels('WARNING')

Note

This will suspend logging for the specific level and all levels below it across all logs.

To resume logging at the previously defined levels, use the reset_log_levels() method.

>>> g.reset_log_levels()

Logging with Color Text¶

With the simple ANSI color capability built into Glusto, it is possible to add color text in logs or other output.

Changing the Color of a String¶

To wrap a string in color, use the colorfy command.

>>> print g.colorfy(g.RED, 'This string is RED')

The printed string will be output in the color red and any following text will return to default color.

See the “Available Color Values” below for the full list of Foreground Colors.

Changing the Background Color of a String¶

It is possible to change the background color of a string.

>>> print g.colorfy(g.BG_YELLOW, 'This string has a YELLOW background')

See the “Available Color Values” below for the full list of Background Colors.

Changing an ANSI Attribute of a String¶

It is also possible to make a string bold.

>>> print g.colorfy(g.BOLD, 'This string is BOLD')

Warning

Mileage may vary depending on the output device.

See the “Available Color Values” below for the full list of Attributes.

Combining Colors and Attributes¶

Glusto allows multiple combinations of color and attributes to be used at the same time.

To combine colors and attributes, pass a Bitwise Or’d list to colorfy().

>>> print g.colorfy(g.BOLD | g. RED | g.BG_YELLOW, 'This string is BOLD and RED on a YELLOW BACKGROUND.')

Tip

Create your own combinations ahead of time for re-use throughout your script.

>>> COLOR_ALERT =  g.BOLD | g.RED | g.REVERSE
>>> COLOR_WARNING =  g.BOLD | g.RED
>>> print '%s %s' %(g.colorfy(COLOR_ALERT, 'WARNING:'), g.colorfy(COLOR_WARNING, 'This is a warning!'))

Send Color Text to the Log¶

Any of the previously discussed print commands can be replaced with logging commands to send the color text to logfiles.

>>> g.log.debug(g.colorfy(g.BOLD | g.RED | g.BG_YELLOW, 'This string is BOLD and RED on a YELLOW BACKGROUND.'))

Enabling Color Logging for Built-In Commands¶

Color output is enabled by default and some of the Glusto internal commands (e.g., g.run()) already use color output for logging.

To disable the built-in color logging, add a line to the Glusto /etc/glusto/defaults.yml file.

log_color: False

To enable the built-in color logging, add a line to the Glusto /etc/glusto/defaults.yml file.

log_color: True

Color output can also be disabled by adding the log_color option to a config file loaded via /usr/bin/glusto -c.

Another method is to set g.config['log_color'] = False directly in your code.

Available Color Values¶

When using the color values listed in the table below, remember to add the Glusto g. reference in front of each color value.

For example, g.BG_LTMAGENTA

BACKGROUND	FOREGROUND	ATTRIBUTES
BG_DEFAULT	DEFAULT	NORMAL
BG_BLACK	BLACK	BOLD
BG_RED	RED	DIM
BG_GREEN	GREEN	UNDERLINE
BG_YELLOW	YELLOW	BLINK
BG_BLUE	BLUE	REVERSE
BG_MAGENTA	MAGENTA	HIDDEN
BG_CYAN	CYAN
BG_LTGRAY	LTGRAY
BG_DKGRAY	DKGRAY
BG_LTRED	LTRED
BG_LTGREEN	LTGREEN
BG_LTYELLOW	LTYELLOW
BG_LTBLUE	LTBLUE
BG_LTMAGENTA	LTMAGENTA
BG_LTCYAN	LTCYAN
BG_WHITE	WHITE