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RegEx for ScheduleExpression that can be used in CloudFormation Template

0

I was writing a CF template today that creates a periodic EventBridge rule. One of the parameters my template therefore accepts is the cron expression for setting the ScheduleExpression on this rule. I struggled for a while getting the expression right for my own use case, and wanted to add an AllowedPattern rule to my parameter. I went looking for a RegEx that I could use, and had no luck. There is a Gist, not updated in a few years, out there that presents this monster:

"^(rate\\(((1 (hour|minute|day))|(\\d+ (hours|minutes|days)))\\))|(cron\\(\\s*($|#|\\w+\\s*=|(\\?|\\*|(?:[0-5]?\\d)(?:(?:-|\/|\\,)(?:[0-5]?\\d))?(?:,(?:[0-5]?\\d)(?:(?:-|\/|\\,)(?:[0-5]?\\d))?)*)\\s+(\\?|\\*|(?:[0-5]?\\d)(?:(?:-|\/|\\,)(?:[0-5]?\\d))?(?:,(?:[0-5]?\\d)(?:(?:-|\/|\\,)(?:[0-5]?\\d))?)*)\\s+(\\?|\\*|(?:[01]?\\d|2[0-3])(?:(?:-|\/|\\,)(?:[01]?\\d|2[0-3]))?(?:,(?:[01]?\\d|2[0-3])(?:(?:-|\/|\\,)(?:[01]?\\d|2[0-3]))?)*)\\s+(\\?|\\*|(?:0?[1-9]|[12]\\d|3[01])(?:(?:-|\/|\\,)(?:0?[1-9]|[12]\\d|3[01]))?(?:,(?:0?[1-9]|[12]\\d|3[01])(?:(?:-|\/|\\,)(?:0?[1-9]|[12]\\d|3[01]))?)*)\\s+(\\?|\\*|(?:[1-9]|1[012])(?:(?:-|\/|\\,)(?:[1-9]|1[012]))?(?:L|W)?(?:,(?:[1-9]|1[012])(?:(?:-|\/|\\,)(?:[1-9]|1[012]))?(?:L|W)?)*|\\?|\\*|(?:JAN|FEB|MAR|APR|MAY|JUN|JUL|AUG|SEP|OCT|NOV|DEC)(?:(?:-)(?:JAN|FEB|MAR|APR|MAY|JUN|JUL|AUG|SEP|OCT|NOV|DEC))?(?:,(?:JAN|FEB|MAR|APR|MAY|JUN|JUL|AUG|SEP|OCT|NOV|DEC)(?:(?:-)(?:JAN|FEB|MAR|APR|MAY|JUN|JUL|AUG|SEP|OCT|NOV|DEC))?)*)\\s+(\\?|\\*|(?:[0-6])(?:(?:-|\/|\\,|#)(?:[0-6]))?(?:L)?(?:,(?:[0-6])(?:(?:-|\/|\\,|#)(?:[0-6]))?(?:L)?)*|\\?|\\*|(?:MON|TUE|WED|THU|FRI|SAT|SUN)(?:(?:-)(?:MON|TUE|WED|THU|FRI|SAT|SUN))?(?:,(?:MON|TUE|WED|THU|FRI|SAT|SUN)(?:(?:-)(?:MON|TUE|WED|THU|FRI|SAT|SUN))?)*)(|\\s)+(\\?|\\*|(?:|\\d{4})(?:(?:-|\/|\\,)(?:|\\d{4}))?(?:,(?:|\\d{4})(?:(?:-|\/|\\,)(?:|\\d{4}))?)*))\\))$"

However, when I tried to use this in a CF template...

Parameters:
  Schedule: {
    Type: String,
    Description: "AWS Schedule Expression representing how often the Lambda will run. Default is once per week, Sunday at noon.",
    AllowedPattern: "^(rate\\(((1 (hour|minute|day))|(\\d+ (hours|minutes|days)))\\))|(cron\\(\\s*($|#|\\w+\\s*=|(\...  ...?)*))\\))$"
    }

This failed and said my yaml was invalid. The column specified pointed to the cause being the escaped forward slashes, i.e. "/". I have read some places that "/" is not a valid escape sequence in the version of yaml that CF uses. Is this true, and does anyone have a regex for ScheduleExpressions that works in a yaml CF template?

The Gist I can the above RegEx from is here: https://gist.github.com/andrew-templeton/aca7fc6c166e9b8a46aa

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Management & UnternehmensführungServerlosAnwendungsintegration
Tags
AWS CloudFormationAmazon EventBridge
Sprache
English
AWS-User-1848579
gefragt vor 2 Jahren986 Aufrufe
2 Antworten
0

Can you try this one?

AllowedPattern: >-
      ^(rate\(((1 (hour|minute|day))|(\d+
      (hours|minutes|days)))\))|(cron\(\s*($|#|\w+\s*=|(\?|\*|(?:[0-5]?\d)(?:(?:-|/|\,)(?:[0-5]?\d))?(?:,(?:[0-5]?\d)(?:(?:-|/|\,)(?:[0-5]?\d))?)*)\s+(\?|\*|(?:[0-5]?\d)(?:(?:-|/|\,)(?:[0-5]?\d))?(?:,(?:[0-5]?\d)(?:(?:-|/|\,)(?:[0-5]?\d))?)*)\s+(\?|\*|(?:[01]?\d|2[0-3])(?:(?:-|/|\,)(?:[01]?\d|2[0-3]))?(?:,(?:[01]?\d|2[0-3])(?:(?:-|/|\,)(?:[01]?\d|2[0-3]))?)*)\s+(\?|\*|(?:0?[1-9]|[12]\d|3[01])(?:(?:-|/|\,)(?:0?[1-9]|[12]\d|3[01]))?(?:,(?:0?[1-9]|[12]\d|3[01])(?:(?:-|/|\,)(?:0?[1-9]|[12]\d|3[01]))?)*)\s+(\?|\*|(?:[1-9]|1[012])(?:(?:-|/|\,)(?:[1-9]|1[012]))?(?:L|W)?(?:,(?:[1-9]|1[012])(?:(?:-|/|\,)(?:[1-9]|1[012]))?(?:L|W)?)*|\?|\*|(?:JAN|FEB|MAR|APR|MAY|JUN|JUL|AUG|SEP|OCT|NOV|DEC)(?:(?:-)(?:JAN|FEB|MAR|APR|MAY|JUN|JUL|AUG|SEP|OCT|NOV|DEC))?(?:,(?:JAN|FEB|MAR|APR|MAY|JUN|JUL|AUG|SEP|OCT|NOV|DEC)(?:(?:-)(?:JAN|FEB|MAR|APR|MAY|JUN|JUL|AUG|SEP|OCT|NOV|DEC))?)*)\s+(\?|\*|(?:[0-6])(?:(?:-|/|\,|#)(?:[0-6]))?(?:L)?(?:,(?:[0-6])(?:(?:-|/|\,|#)(?:[0-6]))?(?:L)?)*|\?|\*|(?:MON|TUE|WED|THU|FRI|SAT|SUN)(?:(?:-)(?:MON|TUE|WED|THU|FRI|SAT|SUN))?(?:,(?:MON|TUE|WED|THU|FRI|SAT|SUN)(?:(?:-)(?:MON|TUE|WED|THU|FRI|SAT|SUN))?)*)(|\s)+(\?|\*|(?:|\d{4})(?:(?:-|/|\,)(?:|\d{4}))?(?:,(?:|\d{4})(?:(?:-|/|\,)(?:|\d{4}))?)*))\))$

This is similar to the one that you posted, but in a yaml-friendly way. It's passing CFN's validation.

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joahna
beantwortet vor 2 Jahren
  • AWS-User-1848579
    vor 2 Jahren

    I think you're on to something, in that this passes validation. Something still needs to be worked out in the regex itself, though. At least when I tried it, setting "cron(10 15 ? * SUN *)" as the default parameter, it complained it didn't match the pattern. This is confirmed to work as ScheduleExpression, however. It's a big chunk of RegEx, that's for sure, especially with the escaped characters. I'll try to work on it.

0

I'm still testing it to be sure, but this should work according to the current EventBridge documentation:

AllowedPattern: # [REMOVED, see below]

Update: I have refactored the pattern and, while it adds significant complexity, it does seem to handle all the edge cases I can think to test and all backslashes were removed (to prevent backslash-escape pandemonium).

It's also up on github, if you find any issues with it:

AllowedPattern: # [REMOVED, see below]

Update #2: Slight tweak, but for the latest version plz go check the github:

AllowedPattern: "^(?:rate[(](?:(?:1[ ]+(hour|minute|day))|(?:[0-9]+[ ]+(hours|minutes|days)))[)])|(?:cron[(](?:(?:(?:[0-5]?[0-9])|[*])(?:(?:[-](?:(?:[0-5]?[0-9])|[*]))|(?:[/][0-9]+))?(?:[,](?:(?:[0-5]?[0-9])|[*])(?:(?:[-](?:(?:[0-5]?[0-9])|[*]))|(?:[/][0-9]+))?)*)[ ]+(?:(?:(?:[0-2]?[0-9])|[*])(?:(?:[-](?:(?:[0-2]?[0-9])|[*]))|(?:[/][0-9]+))?(?:[,](?:(?:[0-2]?[0-9])|[*])(?:(?:[-](?:(?:[0-2]?[0-9])|[*]))|(?:[/][0-9]+))?)*)[ ]+(?:(?:[?][ ]+(?:(?:(?:[1]?[0-9])|(?:JAN|FEB|MAR|APR|MAY|JUN|JUL|AUG|SEP|OCT|NOV|DEC)|[*])(?:(?:[-](?:(?:[1]?[0-9])|(?:JAN|FEB|MAR|APR|MAY|JUN|JUL|AUG|SEP|OCT|NOV|DEC)|[*])(?:[/][0-9]+)?)|(?:[/][0-9]+))?(?:[,](?:(?:[1]?[0-9])|(?:JAN|FEB|MAR|APR|MAY|JUN|JUL|AUG|SEP|OCT|NOV|DEC)|[*])(?:(?:[-](?:(?:[1]?[0-9])|(?:JAN|FEB|MAR|APR|MAY|JUN|JUL|AUG|SEP|OCT|NOV|DEC)|[*])(?:[/][0-9]+)?)|(?:[/][0-9]+))?)*)[ ]+(?:(?:(?:[1-7]|(?:SUN|MON|TUE|WED|THU|FRI|SAT))[#][0-5])|(?:(?:(?:(?:[1-7]|(?:SUN|MON|TUE|WED|THU|FRI|SAT))L?)|[L*])(?:(?:[-](?:(?:(?:[1-7]|(?:SUN|MON|TUE|WED|THU|FRI|SAT))L?)|[L*]))|(?:[/][0-9]+))?(?:[,](?:(?:(?:[1-7]|(?:SUN|MON|TUE|WED|THU|FRI|SAT))L?)|[L*])(?:(?:[-](?:(?:(?:[1-7]|(?:SUN|MON|TUE|WED|THU|FRI|SAT))L?)|[L*]))|(?:[/][0-9]+))?)*)))|(?:(?:(?:(?:(?:[1-3]?[0-9])W?)|LW|[L*])(?:(?:[-](?:(?:(?:[1-3]?[0-9])W?)|LW|[L*]))|(?:[/][0-9]+))?(?:[,](?:(?:(?:[1-3]?[0-9])W?)|LW|[L*])(?:(?:[-](?:(?:(?:[1-3]?[0-9])W?)|LW|[L*]))|(?:[/][0-9]+))?)*)[ ]+(?:(?:(?:[1]?[0-9])|(?:JAN|FEB|MAR|APR|MAY|JUN|JUL|AUG|SEP|OCT|NOV|DEC)|[*])(?:(?:[-](?:(?:[1]?[0-9])|(?:JAN|FEB|MAR|APR|MAY|JUN|JUL|AUG|SEP|OCT|NOV|DEC)|[*])(?:[/][0-9]+)?)|(?:[/][0-9]+))?(?:[,](?:(?:[1]?[0-9])|(?:JAN|FEB|MAR|APR|MAY|JUN|JUL|AUG|SEP|OCT|NOV|DEC)|[*])(?:(?:[-](?:(?:[1]?[0-9])|(?:JAN|FEB|MAR|APR|MAY|JUN|JUL|AUG|SEP|OCT|NOV|DEC)|[*])(?:[/][0-9]+)?)|(?:[/][0-9]+))?)*)[ ]+[?]))[ ]+(?:(?:(?:[12][0-9]{3})|[*])(?:(?:[-](?:(?:[12][0-9]{3})|[*]))|(?:[/][0-9]+))?(?:[,](?:(?:[12][0-9]{3})|[*])(?:(?:[-](?:(?:[12][0-9]{3})|[*]))|(?:[/][0-9]+))?)*)[)])$"
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Evan K
beantwortet vor 2 Monaten

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