README.md

Cron Validator

Features

• Validate unix cron expression
• Match unit cron expression with specific datetime
• Generate match datetime between two datetime
• Schedule tasks

Install

pip install cron-validator

Run Tests

1. Install test requirements

pip install -r requirements/test.txt

2. Run tests (with coverage if wished)

pytest --cov=. test/

Sample

1. Validate unix cron expression

from cron_validator import CronValidator

assert CronValidator.parse('* * * * *') is not None # valid
assert CronValidator.parse('*/3 * * * *') is not None # valid
assert CronValidator.parse('*/61 * * * *') is None # invalid

2. Match unit cron expression with specific datetime

from cron_validator import CronValidator
from cron_validator.util import str_to_datetime

dt_str = '2019-04-23 1:00'
dt = str_to_datetime(dt_str)

assert CronValidator.match_datetime("* * * * *", dt)
assert CronValidator.match_datetime("* * * 4 *", dt)
assert CronValidator.match_datetime("* * * 5 *", dt) is False
assert CronValidator.match_datetime("* * * 1-5 *", dt)
assert CronValidator.match_datetime("* * * 1-3 *", dt) is False
assert CronValidator.match_datetime("* * * 1/5 *", dt) is False
assert CronValidator.match_datetime("* * * * *", dt)
assert CronValidator.match_datetime("0 * * * *", dt)
assert CronValidator.match_datetime("0-30 * * * *", dt)
assert CronValidator.match_datetime("0/30 * * * *", dt)

3. Generate match datetime between two datetime

from cron_validator import CronValidator
from cron_validator.util import str_to_datetime


from_str = '2019-04-22 00:00'
to_str = '2019-04-23 23:59'

for dt in CronValidator.get_execution_time("0 0 * * *",
from_dt=str_to_datetime(from_str), to_dt=str_to_datetime(to_str)):
    print(dt)

# Output:
# 2019-04-22 00:00:00+00:00
# 2019-04-23 00:00:00+00:00

4. Use scheduler for repetitive task

from cron_validator import CronScheduler

cron_string = "*/1 * * * *"
scheduler = CronScheduler(cron_string)

while True:
    if scheduler.time_for_execution():
        # Get's called every full minute (excluding first iteration)
        print("Now is the next scheduled time.")

5. Use extended cron rules based on AWS EventBridge rules (from v1.0.6)

The cron validator supports partially extended rules based on the Amazon EvenBridge rule set. More info.

Currently we support:

• 'L' for day of the month and day of the week
• 'W' for day of the week.

from cron_validator import CronValidator
from cron_validator.util import str_to_datetime
from cron_validator.regexes import Version

dt_str = '2023-04-28 1:00'
dt = str_to_datetime(dt_str)

assert CronValidator.match_datetime("* * * * 30W", dt, version=Version.EB)
assert CronValidator.match_datetime("* * * * 5L", dt, version=Version.EB)

dt_str = "2022-02-28 1:00"
dt = str_to_datetime(dt_str)
assert CronValidator.match_datetime("* * L * *", dt, version=Version.EB)

License

This project is licensed under the MIT License - see the LICENSE.txt file for details