Base Script
Python is an excellent language that makes writing scripts very straightforward. Over the course of writing many scripts, we realized that we were doing some things over and over like creating a logger and accepting command line arguments. Base script is a very simple abstraction that takes care of setting up logging and other basics so you can focus on your application specific logic.
Here are some facilities that Base Script offers:
- Logging
- Accepting command-line arguments using argparse
Installation
pip install basescript
Usage
Here is a simple example to get started
Hello World
helloworld.py
from basescript import BaseScript
class HelloWorld(BaseScript):
def run(self):
print "Hello world"
if __name__ == '__main__':
HelloWorld().start()
NOTE: all examples showcased here are available under the
examplesdirectory
Run the above by doing:
python helloworld.py run
Run script with log level set to DEBUG
python helloworld.py --log-level DEBUG run
Run script with custom log file
python helloworld.py --log-level DEBUG --log mylog run
Command line args, Using the logger
The following is a more involved example
adder.py
from basescript import BaseScript
class Adder(BaseScript):
# The following specifies the script description so that it be used
# as a part of the usage doc when --help option is used during running.
DESC = 'Adds numbers'
def __init__(self):
super(Adder, self).__init__()
self.a = 10
self.b = 20
def define_args(self, parser):
parser.add_argument('c', type=int, help='Number to add')
def run(self):
self.log.info("Starting run of script ...")
print self.a + self.b + self.args.c
self.log.info("Script is done")
if __name__ == '__main__':
Adder().start()
Run the script as follows and observe the usage information shown. Note how the description appears along with the c argument.
python adder.py --help
usage: adder.py [-h] [--name NAME] [--log-level LOG_LEVEL]
[--log-format {json,pretty}] [--log-file LOG_FILE] [--quiet]
[--metric-grouping-interval METRIC_GROUPING_INTERVAL]
[--debug]
{run} ...
Adds numbers
optional arguments:
-h, --help show this help message and exit
--name NAME Name to identify this instance
--log-level LOG_LEVEL
Logging level as picked from the logging module
--log-format {json,pretty}
Force the format of the logs. By default, if the
command is from a terminal, print colorful logs.
Otherwise print json.
--log-file LOG_FILE Writes logs to log file if specified, default: None
--quiet if true, does not print logs to stderr, default: False
--metric-grouping-interval METRIC_GROUPING_INTERVAL
To group metrics based on time interval ex:10 i.e;(10
sec)
--debug To run the code in debug mode
commands:
{run}
python adder.py run --help
usage: adder.py run [-h] c
positional arguments:
c Number to add
optional arguments:
-h, --help show this help message and exit
Run the script now to see the intended output
python adder.py run 30
60
Run the same with info and higher level logs enabled
python adder.py --log-level INFO 30
2016-04-10 13:48:27,356 INFO Starting run of script ...
60
2016-04-10 13:48:27,356 INFO Script is done
--log-level accepts all the values shown at https://docs.python.org/2/library/logging.html#logging-levels.
log is a log object created using python's standard logging module. You can read more about it at https://docs.python.org/2/library/logging.html.
Sub commands
When we have multiple functionalities then there is a way to call or execute each functionality with different sub command.
For example if we have add and subtract in the same script then we can call each functionality with different sub command.
calc.py
from basescript import BaseScript
class Calc(BaseScript):
A = 10
def add(self):
print(self.A + self.args.b)
def sub(self):
print(self.A - self.args.b)
def define_subcommands(self, subcommands):
super(Calc, self).define_subcommands(subcommands)
add_cmd = subcommands.add_parser("add", help="Adds number")
add_cmd.set_defaults(func=self.add)
add_cmd.add_argument('--b', type=int, help="Number to add")
sub_cmd = subcommands.add_parser("sub", help="Subtracts number")
sub_cmd.set_defaults(func=self.sub)
sub_cmd.add_argument('--b', type=int, help="Number to subtract")
if __name__ == '__main__':
Calc().start()
Run
$ python3 calc.py add --b 4
14
$ python3 calc.py sub --b 4
6
Metric-Grouping
When writing a Metric using self.log, you can specify type=metric. If this is done, a background thread will automatically group multiple metrics into one by averaging values (to prevent writing too many log lines). test.py
from basescript import BaseScript
import time
import random
class Stats(BaseScript):
def __init__(self):
super(Stats, self).__init__()
def run(self):
ts = time.time()
while True:
# Metric Format.
self.log.info("stats", time_duration=(time.time()-ts), type="metric", random_number=random.randint(1, 50))
if __name__ == '__main__':
Stats().start()
Run the command to see the output.
python test.py --metric-grouping-interval 5 run
24 Dec 29, 2022
1 Dec 22, 2021
1 Dec 11, 2021
29 Dec 12, 2022
2 Oct 22, 2021
2 Dec 23, 2021
6 Jun 19, 2022
4 Jul 03, 2021
30 Oct 21, 2022
6 Mar 30, 2022
1 Apr 12, 2022
133 Nov 12, 2022
8 Feb 27, 2022
4 Mar 12, 2022
1 Nov 21, 2021
1 Mar 31, 2022
4 Feb 17, 2022
7 Dec 25, 2022
1 Jun 08, 2022
2 Oct 18, 2021