REGO: Is it possible to parse a regex group from the regex statement?-CodePudding

Cant find any information about regex groups, but what i want to do is: Filter out a string of all ARN's, extract the AWS Services from the ARN's, is it even possible in REGO?

What i currently have:

output = matches {
    string := "\"Resource\": \"arn:aws:states:::lambda:invoke\",\r\n \"Resource\": \"arn:aws:states:::lambda:invoke\",\r\n \"FunctionName\": \"arn:aws:lambda:eu-central-1:521439441813:function:lkfp-test-hello:$LATEST\"\r\n  xecution\"\r\n  \"Resource\": \"arn:aws:states:::aws-sdk:s3:createBucket\"\r\n    }\r\n  }\r\n}\r\n"
    matches := regex.find_n(`arn:([^:\n]*):([^:\n]*):([^:\n]*):([^:\n]*):(([^:\/\n]*)[:\/])?(?:[^"]|"")*"`, string, -1)
}

What it gives as a result:

{
    "output": [
        "arn:aws:states:::lambda:invoke\"",
        "arn:aws:states:::lambda:invoke\"",
        "arn:aws:lambda:eu-central-1:521439441813:function:lkfp-test-hello:$LATEST\"",
        "arn:aws:states:::aws-sdk:s3:createBucket\""
    ]
}

What do i actually expect:

{
    "output": [
        "states",
        "states",
        "lambda",
        "states"
    ]
}

CodePudding user response：

apparently changing find_n to find_all_string_submatch_n separates groups.

CodePudding user response：

The pattern ((?=arn:aws:(states|lambda))) finds what you want in the innermost capturing group. This demonstration is in Python because I don't know rego

import re
string = '"\"Resource\": \"arn:aws:states:::lambda:invoke\",\r\n \"Resource\": \"arn:aws:states:::lambda:invoke\",\r\n \"FunctionName\": \"arn:aws:lambda:eu-central-1:521439441813:function:lkfp-test-hello:$LATEST\"\r\n  xecution\"\r\n  \"Resource\": \"arn:aws:states:::aws-sdk:s3:createBucket\"\r\n    }\r\n  }\r\n}\r\n"'
matches=re.findall(r'((?=arn:aws:(states|lambda)))',string)
for m in matches:
    print(m[1])

output

states
states
lambda
states