S3Client on Grafana Labs

abortMultipartUpload

Mon, 21 Sep 2026 15:16:28 +0000

abortMultipartUpload

S3Client.abortMultipartUpload aborts a multipart upload to an S3 bucket.

Parameters

Parameter	Type	Description
bucketName	string	Name of the bucket to delete the multipart object from.
objectKey	string	Name of the multipart object to delete.
uploadId	number	UploadId of the multipart upload to abort.

Returns

Type	Description
`Promise<void>`	A promise that fulfills when the multipart upload has been aborted.

Example

import {
  AWSConfig,
  S3Client,
} from 'https://jslib.k6.io/aws/0.14.0/s3.js';

const awsConfig = new AWSConfig({
  region: __ENV.AWS_REGION,
  accessKeyId: __ENV.AWS_ACCESS_KEY_ID,
  secretAccessKey: __ENV.AWS_SECRET_ACCESS_KEY,
  sessionToken: __ENV.AWS_SESSION_TOKEN,
});

const s3 = new S3Client(awsConfig);

const testBucketName = 'test-jslib-aws';
const testFileKey = 'multipart.txt';

export default async function () {
  // Initialize a multipart upload
  const multipartUpload = await s3.createMultipartUpload(testBucketName, testFileKey);

  // Abort multipart upload
  await s3.abortMultipartUpload(testBucketName, testFileKey, multipartUpload.uploadId);
}

A k6 script that will create a multipart upload and abort the multipart

completeMultipartUpload

Mon, 21 Sep 2026 15:16:28 +0000

completeMultipartUpload

S3Client.completeMultipartUpload uploads a multipart object to an S3 bucket.

Parameters

Parameter	Type	Description
bucketName	string	Name of the bucket to delete the object to.
objectKey	string	Name of the uploaded object.
uploadId	number	UploadId of the multipart upload to complete.
parts	Array< S3Part>	The S3Parts to assemble.

Returns

Type	Description
Promise< S3UploadedObject>	A Promise that fulfills with an S3UploadedObject containing metadata about the completed multipart upload, including ETag and optional checksums.

Example

import crypto from 'k6/crypto';
import exec from 'k6/execution';

import {
  AWSConfig,
  S3Client,
} from 'https://jslib.k6.io/aws/0.14.0/s3.js';

const awsConfig = new AWSConfig({
  region: __ENV.AWS_REGION,
  accessKeyId: __ENV.AWS_ACCESS_KEY_ID,
  secretAccessKey: __ENV.AWS_SECRET_ACCESS_KEY,
  sessionToken: __ENV.AWS_SESSION_TOKEN,
});

const s3 = new S3Client(awsConfig);

const testBucketName = 'test-jslib-aws';
const testFileKey = 'multipart.txt';

export default async function () {
  // List the buckets the AWS authentication configuration
  // gives us access to.
  const buckets = await s3.listBuckets();

  // If our test bucket does not exist, abort the execution.
  if (buckets.filter((b) => b.name === testBucketName).length == 0) {
    exec.test.abort();
  }

  // Produce random bytes to upload of size ~12MB, that
  // we will upload in two 6MB parts. This is done as the
  // minimum part size supported by S3 is 5MB.
  const bigFile = crypto.randomBytes(12 * 1024 * 1024);

  // Initialize a multipart upload
  const multipartUpload = await s3.createMultipartUpload(testBucketName, testFileKey);

  // Upload the first part
  const firstPartData = bigFile.slice(0, 6 * 1024 * 1024);
  const firstPart = await s3.uploadPart(
    testBucketName,
    testFileKey,
    multipartUpload.uploadId,
    1,
    firstPartData
  );

  // Upload the second part
  const secondPartData = bigFile.slice(6 * 1024 * 1024, 12 * 1024 * 1024);
  const secondPart = await s3.uploadPart(
    testBucketName,
    testFileKey,
    multipartUpload.uploadId,
    2,
    secondPartData
  );

  // Complete the multipart upload
  const uploadResult = await s3.completeMultipartUpload(
    testBucketName,
    testFileKey,
    multipartUpload.uploadId,
    [firstPart, secondPart]
  );

  // Access the upload metadata
  console.log('Multipart upload completed! ETag:', uploadResult.eTag);

  if (uploadResult.size) {
    console.log('Total object size:', uploadResult.size);
  }

  // For multipart uploads, the checksum type will typically be "COMPOSITE"
  if (uploadResult.checksumType) {
    console.log('Checksum type:', uploadResult.checksumType);
  }

  // Let's redownload it verify it's correct, and delete it
  const obj = await s3.getObject(testBucketName, testFileKey);
  await s3.deleteObject(testBucketName, testFileKey);
}

A k6 script that will upload a multipart upload to an S3 bucket

copyObject

Mon, 21 Sep 2026 15:16:28 +0000

copyObject

S3Client.copyObject copies an object from one bucket to another.

Parameters

Parameter	Type	Description
sourceBucket	string	Name of the bucket to copy the object from.
sourceKey	string	Name of the object to copy from the source bucket.
destinationBucket	string	Name of the bucket to copy the object to.
destinationKey	string	Name of the destination object.

Returns

Type	Description
`Promise<void>`	A Promise that fulfills when the object has been copied from one bucket to another.

Example

import exec from 'k6/execution';

import {
  AWSConfig,
  S3Client,
} from 'https://jslib.k6.io/aws/0.14.0/s3.js';

const awsConfig = new AWSConfig({
  region: __ENV.AWS_REGION,
  accessKeyId: __ENV.AWS_ACCESS_KEY_ID,
  secretAccessKey: __ENV.AWS_SECRET_ACCESS_KEY,
});

const testFile = open('./bonjour.txt', 'r');
const s3 = new S3Client(awsConfig);
const testBucketName = 'test-jslib-aws';
const testFileKey = 'bonjour.txt';
const testDestinationBucketName = 'test-jslib-aws-destination';

export default async function () {
  // Let's upload our test file to the bucket
  await s3.putObject(testBucketName, testFileKey, testFile);

  // Let's create our destination bucket
  await s3.copyObject(testBucketName, testFileKey, testDestinationBucketName, testFileKey);
}

A k6 script that will copy an object from a source S3 bucket to a destination bucket

createMultipartUpload

Mon, 21 Sep 2026 15:16:28 +0000

createMultipartUpload

S3Client.createMultipartUpload creates a new multipart upload for a given an object key in a bucket.

Parameter	Type	Description
bucketName	string	Name of the bucket to upload the object to.
objectKey	string	Name of the uploaded object.

Returns

Type	Description
Promise< S3MultipartUpload>	A Promise that fulfills with a S3MultipartUpload representing a S3 Multipart Upload.

Example

import {
  AWSConfig,
  S3Client,
} from 'https://jslib.k6.io/aws/0.14.0/s3.js';

const awsConfig = new AWSConfig({
  region: __ENV.AWS_REGION,
  accessKeyId: __ENV.AWS_ACCESS_KEY_ID,
  secretAccessKey: __ENV.AWS_SECRET_ACCESS_KEY,
  sessionToken: __ENV.AWS_SESSION_TOKEN,
});

const s3 = new S3Client(awsConfig);

const testBucketName = 'test-jslib-aws';
const testFileKey = 'multipart.txt';

export default async function () {
  // Initialize a multipart upload
  const multipartUpload = await s3.createMultipartUpload(testBucketName, testFileKey);

  // Abort multipart upload
  await s3.abortMultipartUpload(testBucketName, testFileKey, multipartUpload.uploadId);
}

A k6 script that will create a multipart upload to an S3 bucket

deleteObject

Mon, 21 Sep 2026 15:16:28 +0000

deleteObject

S3Client.deleteObject deletes an object from a bucket.

Parameters

Parameter	Type	Description
bucketName	string	Name of the bucket to delete the object from.
objectKey	string	Name of the object to delete.

Returns

Type	Description
`Promise<void>`	A promise that fulfills when the object has been deleted from S3.

Example

import exec from 'k6/execution';

import {
  AWSConfig,
  S3Client,
} from 'https://jslib.k6.io/aws/0.14.0/s3.js';

const awsConfig = new AWSConfig({
  region: __ENV.AWS_REGION,
  accessKeyId: __ENV.AWS_ACCESS_KEY_ID,
  secretAccessKey: __ENV.AWS_SECRET_ACCESS_KEY,
});

const s3 = new S3Client(awsConfig);
const testBucketName = 'test-jslib-aws';
const testFileKey = 'bonjour.txt';

export default async function () {
  // Let's delete our test object
  await s3.deleteObject(testBucketName, testFileKey);

  // And make sure it was indeed deleted
  const objects = await s3.listObjects();
  if (objects.filter((o) => o.name === testBucketName).length != 0) {
    exec.test.abort();
  }
}

A k6 script that will delete an object from a S3 bucket

getObject

Mon, 21 Sep 2026 15:16:28 +0000

getObject

S3Client.getObject downloads an object from a bucket.

As a default, the object’s data will be treated as a string. In order to treat the object’s data as binary content, and receive the data as an ArrayBuffer, you can pass additionalHeaders to getObject, with the Accept header set to application/octet-stream.

Parameters

Parameter	Type	Description
bucketName	string	Name of the bucket to fetch the object from.
objectKey	string	Name of the object to download.
additionalHeaders	Object	Additional headers to send with the request.

Returns

Type	Description
Promise< Object>	A Promise that fulfills with an Object describing and holding the downloaded content.

Example

Downloading a text file from AWS S3

import exec from 'k6/execution';

import {
  AWSConfig,
  S3Client,
} from 'https://jslib.k6.io/aws/0.14.0/s3.js';

const awsConfig = new AWSConfig({
  region: __ENV.AWS_REGION,
  accessKeyId: __ENV.AWS_ACCESS_KEY_ID,
  secretAccessKey: __ENV.AWS_SECRET_ACCESS_KEY,
});

const s3 = new S3Client(awsConfig);
const testBucketName = 'test-jslib-aws';
const testFileKey = 'bonjour.txt';

export default async function () {
  const objects = await s3.listObjects(testBucketName);

  // If our test object does not exist, abort the execution.
  if (objects.filter((o) => o.key === testFileKey).length == 0) {
    exec.test.abort();
  }

  // Let's download our test object and print its content
  const object = await s3.getObject(testBucketName, testFileKey);
  console.log(JSON.stringify(object));
}

A k6 script that will download an object from a bucket

Downloading a binary file from AWS S3

import exec from 'k6/execution';

import {
  AWSConfig,
  S3Client,
} from 'https://jslib.k6.io/aws/0.14.0/s3.js';

const awsConfig = new AWSConfig({
  region: __ENV.AWS_REGION,
  accessKeyId: __ENV.AWS_ACCESS_KEY_ID,
  secretAccessKey: __ENV.AWS_SECRET_ACCESS_KEY,
});

const s3 = new S3Client(awsConfig);
const testBucketName = 'test-jslib-aws';
const testFileKey = 'quick.pdf';

export default async function () {
  // Download an object from S3, and require from the `getObject` operation
  // to treat it as a binary content's file, and return an Object who's data
  // parameter is an ArrayBuffer.
  const s3Object = await s3.getObject(testBucketName, testFileKey, {
    Accept: 'application/octet-stream',
  });

  console.log(`Successfully downloaded a binary file of size ${s3Object.data.byteLength} bytes`);
}

A k6 script that will download a binary object from a bucket

listBuckets

Mon, 21 Sep 2026 15:16:28 +0000

listBuckets

S3Client.listBuckets() lists the buckets the authenticated user has access to in the region set by the S3Client instance’s configuration.

Returns

Type	Description
Promise<Array< Bucket»	A Promise that fulfills with an array of Bucket objects.

Example

import exec from 'k6/execution';

import {
  AWSConfig,
  S3Client,
} from 'https://jslib.k6.io/aws/0.14.0/s3.js';

const awsConfig = new AWSConfig({
  region: __ENV.AWS_REGION,
  accessKeyId: __ENV.AWS_ACCESS_KEY_ID,
  secretAccessKey: __ENV.AWS_SECRET_ACCESS_KEY,
});

const s3 = new S3Client(awsConfig);
const testBucketName = 'test-jslib-aws';

export default async function () {
  // List the buckets the AWS authentication configuration
  // gives us access to.
  const buckets = await s3.listBuckets();

  // If our test bucket does not exist, abort the execution.
  if (buckets.filter((b) => b.name === testBucketName).length == 0) {
    exec.test.abort();
  }

  // ... work with the bucket's content
}

listObjects

Mon, 21 Sep 2026 15:16:28 +0000

listObjects

S3Client.listObjects() lists the objects contained in a bucket.

Parameters

Parameter	Type	Description
bucketName	string	Name of the bucket to fetch the object from.
prefix (optional)	string	Limits the response to keys that begin with the specified prefix.

Returns

Type	Description
Promise<Array< Object»	A Promise that fulfills with an array of Object objects.

Example

import exec from 'k6/execution';

import {
  AWSConfig,
  S3Client,
} from 'https://jslib.k6.io/aws/0.14.0/s3.js';

const awsConfig = new AWSConfig({
  region: __ENV.AWS_REGION,
  accessKeyId: __ENV.AWS_ACCESS_KEY_ID,
  secretAccessKey: __ENV.AWS_SECRET_ACCESS_KEY,
});

const s3 = new S3Client(awsConfig);
const testBucketName = 'test-jslib-aws';
const testFileKey = 'bonjour.txt';

export default async function () {
  // List our bucket's objects
  const objects = await s3.listObjects(testBucketName);

  // If our test object does not exist, abort the execution.
  if (objects.filter((o) => o.key === testFileKey).length == 0) {
    exec.test.abort();
  }

  // ... work with the bucket's objects
  console.log(JSON.stringify(objects));
}

putObject

Mon, 21 Sep 2026 15:16:28 +0000

putObject

S3Client.putObject uploads an object to a bucket.

Parameters

Parameter	Type	Description
bucketName	string	Name of the bucket to upload the object to.
objectKey	string	Name of the uploaded object.
data	string \| ArrayBuffer	Content of the object to upload.
params	PutObjectParams (optional)	Options for the request.

PutObjectParams

Name	Type	Description
contentDisposition	string (optional)	Specifies presentational information for the object. For more information, see RFC 6266.
contentEncoding	string (optional)	Specifies what content encodings have been applied to the object and thus what decoding mechanisms must be applied to obtain the media-type referenced by the Content-Type header field. For more information, see RFC 2616.
contentLength	number (optional)	Size of the body in bytes. This parameter is useful when the size of the body cannot be determined automatically.
contentMD5	string (optional)	The base64-encoded 128-bit MD5 digest of the message (without the headers) according to RFC 1864. This header can be used as a message integrity check to verify that the received message is identical to the message that was sent.
contentType	string (optional)	A standard MIME type describing the format of the object data. For more information, see RFC 2616.

Returns

Type	Description
Promise< S3UploadedObject>	A Promise that fulfills with an S3UploadedObject containing metadata about the uploaded object, including ETag and optional checksums.

Example

import {
  AWSConfig,
  S3Client,
} from 'https://jslib.k6.io/aws/0.14.0/s3.js';

const awsConfig = new AWSConfig({
  region: __ENV.AWS_REGION,
  accessKeyId: __ENV.AWS_ACCESS_KEY_ID,
  secretAccessKey: __ENV.AWS_SECRET_ACCESS_KEY,
});

const s3 = new S3Client(awsConfig);
const testBucketName = 'test-jslib-aws';
const testFileKey = 'bonjour.txt';
const testFile = open('./bonjour.txt', 'r');

export default async function () {
  // Let's upload our test file to the bucket
  const uploadResult = await s3.putObject(testBucketName, testFileKey, testFile, {
    contentType: 'text/plain',
    contentLength: testFile.length,
  });

  // Access the upload metadata
  console.log('Upload successful! ETag:', uploadResult.eTag);

  if (uploadResult.size) {
    console.log('Object size:', uploadResult.size);
  }

  // Check if checksums are available
  if (uploadResult.sha256) {
    console.log('SHA256 checksum:', uploadResult.sha256);
  }

  // And let's redownload it to verify it's correct
  const obj = await s3.getObject(testBucketName, testFileKey);
  console.log(JSON.stringify(obj));
}

A k6 script that will upload an object to a S3 bucket

uploadPart

Mon, 21 Sep 2026 15:16:28 +0000

uploadPart

S3Client.uploadPart uploads a part to multipart upload in a bucket.

Parameter	Type	Description
bucketName	string	Name of the bucket to upload the object to.
objectKey	string	Name of the object to upload.
uploadId	string	UploadId of the multipart upload.
partNumber	number	The Part number of the Part to upload.
data	string \| ArrayBuffer	Content of the part to upload.

Returns

Type	Description
Promise< S3Part>	A Promise that fulfills with a S3Part representing a S3 Part Upload.

Example

import crypto from 'k6/crypto';
import exec from 'k6/execution';

import {
  AWSConfig,
  S3Client,
} from 'https://jslib.k6.io/aws/0.14.0/s3.js';

const awsConfig = new AWSConfig({
  region: __ENV.AWS_REGION,
  accessKeyId: __ENV.AWS_ACCESS_KEY_ID,
  secretAccessKey: __ENV.AWS_SECRET_ACCESS_KEY,
  sessionToken: __ENV.AWS_SESSION_TOKEN,
});

const s3 = new S3Client(awsConfig);

const testBucketName = 'test-jslib-aws';
const testFileKey = 'multipart.txt';

export default async function () {
  // Produce random bytes to upload of size ~12MB, that
  // we will upload in two 6MB parts. This is done as the
  // minimum part size supported by S3 is 5MB.
  const bigFile = crypto.randomBytes(12 * 1024 * 1024);

  // Initialize a multipart upload
  const multipartUpload = await s3.createMultipartUpload(testBucketName, testFileKey);

  // Upload the first part
  const firstPartData = bigFile.slice(0, 6 * 1024 * 1024);
  const firstPart = await s3.uploadPart(
    testBucketName,
    testFileKey,
    multipartUpload.uploadId,
    1,
    firstPartData
  );

  // Upload the second part
  const secondPartData = bigFile.slice(6 * 1024 * 1024, 12 * 1024 * 1024);
  const secondPart = await s3.uploadPart(
    testBucketName,
    testFileKey,
    multipartUpload.uploadId,
    2,
    secondPartData
  );

  // Complete the multipart upload
  await s3.completeMultipartUpload(testBucketName, testFileKey, multipartUpload.uploadId, [
    firstPart,
    secondPart,
  ]);

  // Let's redownload it verify it's correct, and delete it
  const obj = await s3.getObject(testBucketName, testFileKey);
  await s3.deleteObject(testBucketName, testFileKey);
}

A k6 script that will upload a part in a multipart upload to an S3 bucket

Bucket

Mon, 21 Sep 2026 15:16:28 +0000

Bucket

Bucket is returned by the S3Client.* methods that query S3 buckets. Namely, listBuckets() returns an array of Bucket objects. The Bucket object describes an Amazon S3 bucket.

Name	Type	Description
`Bucket.name`	string	The S3 bucket’s name
`Bucket.creationDate`	Date	The S3 bucket’s creationDate

Example

import {
  AWSConfig,
  S3Client,
} from 'https://jslib.k6.io/aws/0.14.0/s3.js';

const awsConfig = new AWSConfig({
  region: __ENV.AWS_REGION,
  accessKeyId: __ENV.AWS_ACCESS_KEY_ID,
  secretAccessKey: __ENV.AWS_SECRET_ACCESS_KEY,
});

const s3 = new S3Client(awsConfig);

export default async function () {
  // List the buckets the AWS authentication configuration
  // gives us access to.
  const buckets = await s3.listBuckets();
  console.log(JSON.stringify(buckets));
}

A k6 script that will query the user’s S3 buckets and print all of their metadata

Object

Mon, 21 Sep 2026 15:16:28 +0000

Object

Object is returned by the S3Client.* methods that query S3 buckets’ objects. Namely, listObjects, getObject, putObject, and deleteObject. The Object construct describes an Amazon S3 object.

Name	Type	Description
`Object.key`	string	The S3 object’s name.
`Object.lastModified`	number	The S3 object’s last modification date.
`Object.etag`	string	The S3 object’s `etag` is a hash of the object. The ETag reflects changes only to the contents of an object, not its metadata. The ETag may or may not be an MD5 digest of the object data.
`Object.size`	size	The S3 object’s size in bytes.
`Object.storageClass`	`STANDARD` \| `REDUCED_REDUNDANCY` \| `GLACIER` \| `STANDARD_IA` \| `INTELLIGENT_TIERING` \| `DEEP_ARCHIVE` \| `OUTPOSTS` \| `GLACIER_IR`	The S3 object’s class of storage used to store it.
`Object.data`	`string` or `bytes` or `null`	The S3 object’s content.

Example

import exec from 'k6/execution';

import {
  // listBuckets,
  AWSConfig,
  S3Client,
} from 'https://jslib.k6.io/aws/0.14.0/s3.js';

const awsConfig = new AWSConfig({
  region: __ENV.AWS_REGION,
  accessKeyId: __ENV.AWS_ACCESS_KEY_ID,
  secretAccessKey: __ENV.AWS_SECRET_ACCESS_KEY,
});

const s3 = new S3Client(awsConfig);
const testBucketName = 'test-jslib-aws';
const testFileKey = 'bonjour.txt';

export default async function () {
  const objects = await s3.listObjects(testBucketName);

  // If our test object does not exist, abort the execution.
  if (objects.filter((o) => o.key === testFileKey).length == 0) {
    exec.test.abort();
  }

  // Let's download our test object and print its content
  const object = await s3.getObject(testBucketName, testFileKey);
  console.log(JSON.stringify(object));
}

A k6 script that will query a S3 bucket’s objects and print its content and metadata

S3MultipartUpload

Mon, 21 Sep 2026 15:16:28 +0000

S3MultipartUpload

S3MultipartUpload is returned by the createMultipartUpload(bucketName, objectKey) method when creating a multipart upload.

Name	Type	Description
`S3MultipartUpload.key`	string	The S3 Multipart object’s key
`S3MultipartUpload.uploadId`	Date	The S3 Multipart upload Id

Example

import {
  AWSConfig,
  S3Client,
} from 'https://jslib.k6.io/aws/0.14.0/s3.js';

const awsConfig = new AWSConfig({
  region: __ENV.AWS_REGION,
  accessKeyId: __ENV.AWS_ACCESS_KEY_ID,
  secretAccessKey: __ENV.AWS_SECRET_ACCESS_KEY,
  sessionToken: __ENV.AWS_SESSION_TOKEN,
});

const s3 = new S3Client(awsConfig);

const testBucketName = 'test-jslib-aws';
const testFileKey = 'multipart.txt';

export default async function () {
  // Initialize a multipart upload
  const multipartUpload = await s3.createMultipartUpload(testBucketName, testFileKey);
  console.log(multipartUpload.uploadId);

  // Abort multipart upload
  await s3.abortMultipartUpload(testBucketName, testFileKey, multipartUpload.uploadId);
}

A k6 script that will create a multipart upload and log the multipart uploadId and abort the multipart upload

S3Part

Mon, 21 Sep 2026 15:16:28 +0000

S3Part

S3Part is returned by the uploadPart(bucketName, objectKey, uploadId, partNumber, data) method when uploading a part to a multipart upload. The S3Part object describes an Amazon S3 Part.

Name	Type	Description
`S3Part.partNumber`	number	The S3 Part’number
`S3Part.eTag`	String	The S3 Part’s etag

Example

import crypto from 'k6/crypto';
import exec from 'k6/execution';

import {
  AWSConfig,
  S3Client,
} from 'https://jslib.k6.io/aws/0.14.0/s3.js';

const awsConfig = new AWSConfig({
  region: __ENV.AWS_REGION,
  accessKeyId: __ENV.AWS_ACCESS_KEY_ID,
  secretAccessKey: __ENV.AWS_SECRET_ACCESS_KEY,
  sessionToken: __ENV.AWS_SESSION_TOKEN,
});

const s3 = new S3Client(awsConfig);

const testBucketName = 'test-jslib-aws';
const testFileKey = 'multipart.txt';

export default async function () {
  // Produce random bytes to upload of size ~12MB, that
  // we will upload in two 6MB parts. This is done as the
  // minimum part size supported by S3 is 5MB.
  const bigFile = crypto.randomBytes(12 * 1024 * 1024);

  // Initialize a multipart upload
  const multipartUpload = await s3.createMultipartUpload(testBucketName, testFileKey);

  // Upload the first part
  const firstPartData = bigFile.slice(0, 6 * 1024 * 1024);
  const firstPart = await s3.uploadPart(
    testBucketName,
    testFileKey,
    multipartUpload.uploadId,
    1,
    firstPartData
  );

  // Upload the second part
  const secondPartData = bigFile.slice(6 * 1024 * 1024, 12 * 1024 * 1024);
  const secondPart = await s3.uploadPart(
    testBucketName,
    testFileKey,
    multipartUpload.uploadId,
    2,
    secondPartData
  );

  // Complete the multipart upload
  await s3.completeMultipartUpload(testBucketName, testFileKey, multipartUpload.uploadId, [
    firstPart,
    secondPart,
  ]);

  // Let's redownload it verify it's correct, and delete it
  const obj = await s3.getObject(testBucketName, testFileKey);
  await s3.deleteObject(testBucketName, testFileKey);
}

A k6 script that will upload a part in a multipart upload to an S3 bucket

S3UploadedObject

Mon, 21 Sep 2026 15:16:28 +0000

S3UploadedObject

S3UploadedObject represents the response returned by S3 upload operations such as putObject and completeMultipartUpload. It contains metadata about the uploaded object, including checksums and upload verification information.

Properties

Name	Type	Description
eTag	string	The entity tag (ETag) of the uploaded object. This is a hash of the object that can be used to verify the integrity of the uploaded data.
crc32	string (optional)	The base64-encoded CRC32 checksum of the uploaded object, if available.
crc32c	string (optional)	The base64-encoded CRC32C checksum of the uploaded object, if available.
crc64nvme	string (optional)	The base64-encoded CRC64NVME checksum of the uploaded object, if available.
sha1	string (optional)	The base64-encoded SHA1 checksum of the uploaded object, if available.
sha256	string (optional)	The base64-encoded SHA256 checksum of the uploaded object, if available.
checksumType	string (optional)	The type of checksum algorithm used. Can be “COMPOSITE” for multipart uploads or “FULL_OBJECT” for single-part uploads.
size	number (optional)	The size of the uploaded object in bytes, if available.

Example

import {
  AWSConfig,
  S3Client,
} from 'https://jslib.k6.io/aws/0.14.0/s3.js';

const awsConfig = new AWSConfig({
  region: __ENV.AWS_REGION,
  accessKeyId: __ENV.AWS_ACCESS_KEY_ID,
  secretAccessKey: __ENV.AWS_SECRET_ACCESS_KEY,
});

const s3 = new S3Client(awsConfig);
const testBucketName = 'test-jslib-aws';
const testFileKey = 'test-file.txt';

export default async function () {
  const testData = 'Hello, World!';

  // Upload the object and get the upload response
  const uploadResult = await s3.putObject(testBucketName, testFileKey, testData);

  // Access the upload metadata
  console.log('Upload ETag:', uploadResult.eTag);
  console.log('Object size:', uploadResult.size);

  // Check if checksums are available
  if (uploadResult.sha256) {
    console.log('SHA256 checksum:', uploadResult.sha256);
  }

  if (uploadResult.checksumType) {
    console.log('Checksum type:', uploadResult.checksumType);
  }

  // Verify the upload was successful
  if (uploadResult.eTag) {
    console.log('Upload successful, ETag received:', uploadResult.eTag);
  }
}

Usage in Multipart Uploads

For multipart uploads, the S3UploadedObject is returned by the completeMultipartUpload method:

import crypto from 'k6/crypto';
import {
  AWSConfig,
  S3Client,
} from 'https://jslib.k6.io/aws/0.14.0/s3.js';

const awsConfig = new AWSConfig({
  region: __ENV.AWS_REGION,
  accessKeyId: __ENV.AWS_ACCESS_KEY_ID,
  secretAccessKey: __ENV.AWS_SECRET_ACCESS_KEY,
});

const s3 = new S3Client(awsConfig);

export default async function () {
  const testBucketName = 'test-jslib-aws';
  const testFileKey = 'large-file.txt';

  // Create large file data
  const bigFile = crypto.randomBytes(12 * 1024 * 1024); // 12MB

  // Initialize multipart upload
  const multipartUpload = await s3.createMultipartUpload(testBucketName, testFileKey);

  // Upload parts
  const firstPart = await s3.uploadPart(
    testBucketName,
    testFileKey,
    multipartUpload.uploadId,
    1,
    bigFile.slice(0, 6 * 1024 * 1024)
  );

  const secondPart = await s3.uploadPart(
    testBucketName,
    testFileKey,
    multipartUpload.uploadId,
    2,
    bigFile.slice(6 * 1024 * 1024)
  );

  // Complete the multipart upload and get the result
  const uploadResult = await s3.completeMultipartUpload(
    testBucketName,
    testFileKey,
    multipartUpload.uploadId,
    [firstPart, secondPart]
  );

  // Access the completed upload metadata
  console.log('Multipart upload ETag:', uploadResult.eTag);
  console.log('Checksum type:', uploadResult.checksumType); // Likely "COMPOSITE"

  if (uploadResult.size) {
    console.log('Total object size:', uploadResult.size);
  }
}