Enforce AllowedPattern for parameter of type CommaDelimitedList in Cloudformation script

Question

I'm trying to enforce an allowed pattern with regex on my parameter, but when I try to build my stack, I get the following error message:

Template validation error: Template error: Parameter 'myParam' AllowedPattern must be on a parameter of type String

This is my Parameter definition:

"myParam": {
   "Description": "this is my param",
   "Type": "CommaDelimitedList",
   "AllowedPattern": "\\+[0-9\\-\\ ]+",
   "MinLength": "1"
 }

Answer 1

I believe you can't do regex on CommaDelimitedList. Regex can only be applied on strings.

CommaDelimitedList – An array of literal strings that are separated by commas

Answer 2

Your parameter is of type CommaDelimitedList , not String . Attribute AllowedPattern (also MinLength ) only applies to type String .

See eg http://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/parameters-section-structure.html for more details.

Answer 3

AllowedPattern (and AllowedValues) for CommaDelimitedLists are now supported in CloudFormation parameters. If you apply an AllowedPattern or AllowedValues on a CommaDelimitedList, the constraint is checked for each item in the list. See the documentation here:

https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/parameters-section-structure.html