AWSCronExpressionValidator

Validates these AWS EventBridge cron expressions, which are similar to, but not compatible with Unix style cron expressions;

Field	Values	Wildcards
Minute	0-59	, - * /
Hour	0-23	, - * /
Day-of-month	1-31	, - * ? / L W
Month	1-12 or JAN-DEC	, - * /
Day-of-week	1-7 or SUN-SAT	, - * ? L #
Year	1970-2199	, - * /

• It appears AWS's wildcard support borrows heavily from Quartz Job Scheduler cron expressions. More documentation about wildcard handling than AWS provides is available in the Cron Trigger Tutorial. NB: AWS doesn't support seconds (i.e. AWS has 6 fields, while Quartz has 7), so ignore the first field in the Quartz documenation.

This was inspired by Niloy Chakraborty's AWSCronValidator.py project.

Installing

To install the library run;

pip install aws-cron-expression-validator

Usage

from aws_cron_expression_validator.validator import AWSCronExpressionValidator, AWSCronExpressionMinuteError

my_expression = "0 180 ? * MON-FRI *"
try:
    AWSCronExpressionValidator.validate(my_expression)
except AWSCronExpressionMinuteError as e:
    print(f"Oh no! My expression has an invalid minute field: {e}")
except ValueError as e:
    print(f"Oh no! My expression was invalid: {e}")