ARNer

Amazon Resource Names (ARNs) uniquely identify AWS resources. We require an ARN when you need to specify a resource unambiguously across all of AWS, such as in IAM policies, Amazon Relational Database Service (Amazon RDS) tags, and API calls.

Amazon Resource Names Documentation

The official AWS Golang SDK library has a simple ARN parsing function (Parse) which is not actually accurate if you need to know the exact resource's name and/or path and/or resource type (i.e. role, group, table, cluster, etc.)

This library correctly parse AWS ARN strings and outputs a BetterARN struct.

type BetterARN struct {
	// The partition that the resource is in. For standard AWS regions, the partition is "aws". If you have resources in
	// other partitions, the partition is "aws-partitionname". For example, the partition for resources in the China
	// (Beijing) region is "aws-cn".
	Partition string

	// The service namespace that identifies the AWS product (for example, Amazon S3, IAM, or Amazon RDS). For a list of
	// namespaces, see
	// http://docs.aws.amazon.com/general/latest/gr/aws-arns-and-namespaces.html#genref-aws-service-namespaces.
	Service string

	// The region the resource resides in. Note that the ARNs for some resources do not require a region, so this
	// component might be omitted.
	Region string

	// The ID of the AWS account that owns the resource, without the hyphens. For example, 123456789012. Note that the
	// ARNs for some resources don't require an account number, so this component might be omitted.
	AccountID string

	// The content of this part of the ARN varies by service. It often includes an indicator of the type of resource —
	// for example, an IAM user or Amazon RDS database - followed by a slash (/) or a colon (:), followed by the
	// resource name itself. Some services allows paths for resource names, as described in
	// http://docs.aws.amazon.com/general/latest/gr/aws-arns-and-namespaces.html#arns-paths.
	ResourceType string

	// The actual resource name that the ARN is pointing to;
	// for example, a DynamoDB table arn:aws:dynamodb:::table/thistableprod real name is thistableprod.
	Resource string

	// Paths can be use to logically separate resources like Organization Units for Users/Roles or specify subdirectory in S3 buckets.
	Path string
}

Example

package main

import (
	"fmt"
	"log"

	"github.com/notdodo/arner"
)

func main() {
	arn := "arn:aws:iam::111111111111:user/division_abc/subdivision_xyz/JaneDoe"

	betterARN, err := arner.ParseARN(arn)
	if err != nil {
		log.Fatalln(err)
	}

	fmt.Println(betterARN)
}

Output will be:

{
  "Partition": "aws",
  "Service": "iam",
  "Region": "",
  "AccountID": "111111111111",
  "ResourceType": "user",
  "Resource": "JaneDoe",
  "Path": "division_abc/subdivision_xyz"
}

Why?

Because the default AWS SDK Golang library V2, for the previous example returns:

{
  "Partition": "aws",
  "Service": "iam",
  "Region": "",
  "AccountID": "111111111111",
  "Resource": "user/division_abc/subdivision_xyz/JaneDoe"
}

In my case I need the exact name of the resource, not the complete path plus the resource type plus other garbage.