Invalid S3 arn error thrown for valid format

[FelixMarcus]

What?

Smithy middleware-endpoint is unable to properly recognise an S3 bucket arn following the format:

arn:aws:s3:::bucket_name

...despite it being the the expected standard.

Instead, it will throw an error of Invalid ARN: ${bucketName} was an invalid ARN.

Expected Behaviour

S3 ARN values without an account id should be valid and thus not throw an error.

Where?

Tested on:

node@v18.19.0

Using:

• @aws-sdk/client-s3@3.472.0
• @aws-sdk/middleware-sdk-s3@3.470.0
• @smithy/middleware-endpoint@2.2.3

Example

N.B. s3BucketExampleArn is passed in via cloudformation as an environment variable, and shows up correctly in the logs - matching an existing bucket in the accounts.

import { PutObjectCommand, S3Client } from '@aws-sdk/client-s3';

const input = {
      Body: JSON.stringify(payloads),
      Bucket: s3BucketExampleArn,
      Key: `example-key`,
    };
const command = new PutObjectCommand(input);
await this.s3Client.send(command);

/usr/src/app/node_modules/@smithy/middleware-endpoint/dist-cjs/service-customizations/s3.js:39
        throw new Error(`Invalid ARN: ${bucketName} was an invalid ARN.`);
              ^
Error: Invalid ARN: arn:aws:s3:::s3BucketExampleArn was an invalid ARN.
    at isArnBucketName (/usr/src/app/node_modules/@smithy/middleware-endpoint/dist-cjs/service-customizations/s3.js:39:15)
    at resolveParamsForS3 (/usr/src/app/node_modules/@smithy/middleware-endpoint/dist-cjs/service-customizations/s3.js:9:37)
    at resolveParams (/usr/src/app/node_modules/@smithy/middleware-endpoint/dist-cjs/adaptors/getEndpointFromInstructions.js:47:63)
    at process.processTicksAndRejections (node:internal/process/task_queues:95:5)
    at async getEndpointFromInstructions (/usr/src/app/node_modules/@smithy/middleware-endpoint/dist-cjs/adaptors/getEndpointFromInstructions.js:15:28)
    at async /usr/src/app/node_modules/@smithy/middleware-endpoint/dist-cjs/endpointMiddleware.js:9:26
    at async /usr/src/app/node_modules/@aws-sdk/middleware-sdk-s3/dist-cjs/region-redirect-endpoint-middleware.js:14:24
    at async /usr/src/app/node_modules/@aws-sdk/middleware-sdk-s3/dist-cjs/region-redirect-middleware.js:9:20
    at async /usr/src/app/node_modules/@aws-sdk/client-s3/node_modules/@aws-sdk/middleware-logger/dist-cjs/loggerMiddleware.js:7:26

[bitIO]

It seems this function

smithy-typescript/packages/middleware-endpoint/src/service-customizations/s3.ts

Line 61 in 3d9d603

export const isArnBucketName = (bucketName: string): boolean => {

is not following the standard since it expects the account to be present even though arn:aws:s3:::my-bucket is a valid arn