Common AWS Related Regex (AWS)

aws_regex_cheat_sheet

ARN Base Pattern :-

arn:<aws_parition>:<aws_service>:[<aws_region>]:<account_id>:<root | resource_type>:/<resource_name>[/<sub_resource_names>...]

i. <aws_partition>
Regex - (aws|aws-us-gov|aws-cn)

ii. <aws_service> - No fixed pattern
iii. <aws_region> - No fixed pattern
Most of the regions occur in combination of 2 letter followed by "-" followed by a combination of direction based word , followed by a "-" and then a digit.
Ref : AWS' regions are listed here https://aws.amazon.com/about-aws/global-infrastructure/regions_az
General Regex - (af|ap|ca|eu|me|sa|us)-(central|north|(north(?:east|west))|south|south(?:east|west)|east|west)-\d+
Note: Availability Zone - Since AZ has a letter added to a  region, it can be of following regex:-
(af|ap|ca|eu|me|sa|us)-(central|north|(north(?:east|west))|south|south(?:east|west)|east|west)-\d+[a-z]{1}

iv. <account_id> - Its a 12 digit number
Regex - \d{12}

v. <resource_type>, <resource_name> and <sub-resources> ... do not have a standard convention.

Below , I have tried capturing things that I have encountered as part of my daily operations.

Service Specific Regex:- 

IAM 
Paths have not been considered in below regex. It adds up to more complexity.
1. User:-
i. Arn
Ref : https://docs.aws.amazon.com/IAM/latest/UserGuide/reference_iam-quotas.html
Regex : ^(?:\d{12}|(arn:(aws|aws-us-gov|aws-cn):iam::\d{12}(?:|:(?:root|user\/[0-9A-Za-z\+\.@_,-]{1,64}))))$
Note: The above regex will also accomodate 12 digit account number as root can also be represented with the account number.
Pure User ARN (without considering account number alone) : ^(arn:(aws|aws-us-gov|aws-cn):iam::\d{12}(?:|:(?:root|user\/[0-9A-Za-z\+\.@_,-]{1,64})))$
Pure User ARN(without considering root or account number):  ^(arn:(aws|aws-us-gov|aws-cn):iam::\d{12}:user\/[0-9A-Za-z\+\.@_,-]{1,64})$
ii. ID
Ref: https://docs.aws.amazon.com/IAM/latest/UserGuide/reference_iam-quotas.html
Regex: AIDA[A-Z0-9]{1,124}

here is an updated version with an automatic test:

import botocore, json, re

REGEXP = '(af|il|ap|ca|eu|me|sa|us|cn|us-gov|us-iso|us-isob)-(central|north|(north(?:east|west))|south|south(?:east|west)|east|west)-\d{1}'


regions = []
json_file = botocore.__file__.replace('__init__.py', 'data/endpoints.json')
for parition in json.load(open(json_file))['partitions']:
    regions += list(parition['regions'].keys())

for region in regions:
    print(region, 'match' if re.match(REGEXP, region) else 'ERROR')

in Jan 2024 this gives:

af-south-1 match
ap-east-1 match
ap-northeast-1 match
ap-northeast-2 match
ap-northeast-3 match
ap-south-1 match
ap-south-2 match
ap-southeast-1 match
ap-southeast-2 match
ap-southeast-3 match
ap-southeast-4 match
ca-central-1 match
eu-central-1 match
eu-central-2 match
eu-north-1 match
eu-south-1 match
eu-south-2 match
eu-west-1 match
eu-west-2 match
eu-west-3 match
il-central-1 match
me-central-1 match
me-south-1 match
sa-east-1 match
us-east-1 match
us-east-2 match
us-west-1 match
us-west-2 match
cn-north-1 match
cn-northwest-1 match
us-gov-east-1 match
us-gov-west-1 match
us-iso-east-1 match
us-iso-west-1 match
us-isob-east-1 match