S3 API

Alluxio supports a RESTful API that is compatible with the basic operations of the Amazon S3 API.

The Alluxio S3 API should be used by applications designed to communicate with an S3-like storage and would benefit from the other features provided by Alluxio, such as data caching, data sharing with file system based applications, and storage system abstraction (e.g., using Ceph instead of S3 as the backing store). For example, a simple application that downloads reports generated by analytic tasks can use the S3 API instead of the more complex file system API.

There are performance implications of using the S3 API. The S3 API leverages the Alluxio proxy, introducing an extra hop. For optimal performance, it is recommended to run the proxy server and an Alluxio worker on each compute node. It is also recommended to put all the proxy servers behind a load balancer.

Features support

The following table describes the support status for current Amazon S3 functional features:

S3 Feature	Status
List Buckets	Supported
List Objects	Supported
List ObjectsV2	Supported
Delete Buckets	Supported
Create Bucket	Supported
Bucket Lifecycle	Not Supported
Policy (Buckets, Objects)	Not Supported
Bucket ACLs (Get, Put)	Not Supported
Bucket Location	Not Supported
Bucket Notification	Not Supported
Bucket Object Versions	Not Supported
Get Bucket Info (HEAD)	Not Supported
Put Object	Supported
Delete Object	Supported
Delete Objects	Supported
Get Object	Supported
Get Object Info (HEAD)	Supported
Get Object (Range Query)	Supported
Object ACLs (Get, Put)	Not Supported
POST Object	Not Supported
Copy Object	Supported
Multipart Uploads	Supported

Language support

Alluxio S3 client supports various programming languages, such as C++, Java, Python, Golang, and Ruby. In this documentation, we use curl REST calls and python S3 client as usage examples.

Example Usage

REST API

For example, you can run the following RESTful API calls to an Alluxio cluster running on localhost. The Alluxio proxy is listening at port 39999 by default.

Authorization

By default, the user that is used to do any FileSystem operations is the user that was used to launch the proxy process. This can be changed by providing the Authorization Header. The header format is defined by the AWS S3 Rest API reference

$ curl -i -H "Authorization: AWS4-HMAC-SHA256 Credential=newuser/20211101/us-east-1/s3/aws4_request SignedHeaders=host;range;x-amz-date Signature=<sig>" \
    -X PUT http://localhost:39999/api/v1/s3/testbucket0
HTTP/1.1 200 OK
Date: Tue, 02 Mar 2021 00:02:26 GMT
Content-Length: 0
Server: Jetty(9.4.31.v20200723)

$ bin/alluxio fs ls /
drwxr-xr-x  testuser                                    0       PERSISTED 03-01-2021 16:02:26:547  DIR /testbucket0

Create a bucket

$ curl -i -X PUT http://localhost:39999/api/v1/s3/testbucket

HTTP/1.1 200 OK
Date: Tue, 18 Jun 2019 21:23:18 GMT
Content-Length: 0
Server: Jetty(9.2.z-SNAPSHOT)

List all buckets owned by the user

Authenticating as a user is necessary to have buckets returned by this operation.

$ curl -i -H "Authorization: AWS testuser:" -X GET http://localhost:39999/api/v1/s3
HTTP/1.1 200 OK
Date: Tue, 02 Mar 2021 00:06:43 GMT
Content-Type: application/xml
Content-Length: 109
Server: Jetty(9.4.31.v20200723)

<ListAllMyBucketsResult><Buckets><Bucket><Name>testbucket0</Name></Bucket></Buckets></ListAllMyBucketsResult>%

Get the bucket (listing objects)

$ curl -i -X GET http://localhost:39999/api/v1/s3/testbucket

HTTP/1.1 200 OK
Date: Wed, 22 Sep 2021 07:13:37 GMT
Content-Type: application/xml
Content-Length: 193
Server: Jetty(9.4.43.v20210629)

<ListBucketResult><KeyCount>0</KeyCount><MaxKeys>1000</MaxKeys><Delimiter>/</Delimiter><EncodingType>url</EncodingType><IsTruncated>false</IsTruncated><Name>testbucket</Name></ListBucketResult>

Put an object

Assuming there is an existing file on local file system called LICENSE:

$ curl -i -X PUT -T "LICENSE" http://localhost:39999/api/v1/s3/testbucket/testobject

HTTP/1.1 100 Continue

HTTP/1.1 200 OK
Date: Tue, 18 Jun 2019 21:24:32 GMT
ETag: "911df44b7ff57801ca8d74568e4ebfbe"
Content-Length: 0
Server: Jetty(9.2.z-SNAPSHOT)

Get the object:

$ curl -i -X GET http://localhost:39999/api/v1/s3/testbucket/testobject

HTTP/1.1 200 OK
Date: Tue, 18 Jun 2019 21:24:57 GMT
Last-Modified: Tue, 18 Jun 2019 21:24:33 GMT
Content-Type: application/xml
Content-Length: 27040
Server: Jetty(9.2.z-SNAPSHOT)

.................. Content of the test file ...................

Listing a bucket with one object

$ curl -i -X GET http://localhost:39999/api/v1/s3/testbucket

HTTP/1.1 200 OK
Date: Wed, 22 Sep 2021 07:15:19 GMT
Content-Type: application/xml
Content-Length: 306
Server: Jetty(9.4.43.v20210629)

<ListBucketResult><Contents><LastModified>2021-09-22T15:14:40.754Z</LastModified><Key>testobject</Key><Size>27040</Size></Contents><KeyCount>1</KeyCount><MaxKeys>1000</MaxKeys><Delimiter>/</Delimiter><EncodingType>url</EncodingType><IsTruncated>false</IsTruncated><Name>testbucket</Name></ListBucketResult>

Listing a bucket with multiple objects

You can upload more files and use the max-keys and marker as the GET bucket request parameter. For example:

$ curl -i -X PUT -T "LICENSE" http://localhost:39999/api/v1/s3/testbucket/key1

HTTP/1.1 100 Continue

HTTP/1.1 200 OK
Date: Tue, 18 Jun 2019 21:26:05 GMT
ETag: "911df44b7ff57801ca8d74568e4ebfbe"
Content-Length: 0
Server: Jetty(9.2.z-SNAPSHOT)

$ curl -i -X PUT -T "LICENSE" http://localhost:39999/api/v1/s3/testbucket/key2

HTTP/1.1 100 Continue

HTTP/1.1 200 OK
Date: Tue, 18 Jun 2019 21:26:28 GMT
ETag: "911df44b7ff57801ca8d74568e4ebfbe"
Content-Length: 0
Server: Jetty(9.2.z-SNAPSHOT)

$ curl -i -X PUT -T "LICENSE" http://localhost:39999/api/v1/s3/testbucket/key3

HTTP/1.1 100 Continue

HTTP/1.1 200 OK
Date: Tue, 18 Jun 2019 21:26:43 GMT
ETag: "911df44b7ff57801ca8d74568e4ebfbe"
Content-Length: 0
Server: Jetty(9.2.z-SNAPSHOT)

$ curl -i -X GET http://localhost:39999/api/v1/s3/testbucket\?max-keys\=2

HTTP/1.1 200 OK
Date: Wed, 22 Sep 2021 07:18:18 GMT
Content-Type: application/xml
Content-Length: 444
Server: Jetty(9.4.43.v20210629)

<ListBucketResult><Contents><LastModified>2021-09-22T15:17:39.579Z</LastModified><Key>key1</Key><Size>27040</Size></Contents><Contents><LastModified>2021-09-22T15:17:41.463Z</LastModified><Key>key2</Key><Size>27040</Size></Contents><KeyCount>2</KeyCount><MaxKeys>2</MaxKeys><Delimiter>/</Delimiter><EncodingType>url</EncodingType><NextMarker>/testbucket/key2</NextMarker><IsTruncated>true</IsTruncated><Name>testbucket</Name></ListBucketResult>

$ curl -i -X GET http://localhost:39999/api/v1/s3/testbucket\?max-keys\=2\&marker\=\/testbucket\/key2

HTTP/1.1 200 OK
Date: Wed, 22 Sep 2021 07:25:21 GMT
Content-Type: application/xml
Content-Length: 477
Server: Jetty(9.4.43.v20210629)

<ListBucketResult><Contents><LastModified>2021-09-22T15:17:39.579Z</LastModified><Key>key1</Key><Size>27040</Size></Contents><Contents><LastModified>2021-09-22T15:17:41.463Z</LastModified><Key>key2</Key><Size>27040</Size></Contents><Marker>/testbucekt/key2</Marker><KeyCount>2</KeyCount><MaxKeys>2</MaxKeys><Delimiter>/</Delimiter><EncodingType>url</EncodingType><NextMarker>/testbucket/key2</NextMarker><IsTruncated>true</IsTruncated><Name>testbucket</Name></ListBucketResult>

You can also verify those objects are represented as Alluxio files, under /testbucket directory.

$ ./bin/alluxio fs ls -R /testbucket

-rw-r--r--  alluxio        staff                    27040       PERSISTED 06-18-2019 14:26:05:694 100% /testbucket/key1
-rw-r--r--  alluxio        staff                    27040       PERSISTED 06-18-2019 14:26:28:153 100% /testbucket/key2
-rw-r--r--  alluxio        staff                    27040       PERSISTED 06-18-2019 14:26:43:081 100% /testbucket/key3
-rw-r--r--  alluxio        staff                    27040       PERSISTED 06-18-2019 14:24:33:029 100% /testbucket/testobject

Copy an Object

$ curl -i -X PUT -H "x-amz-copy-source: /testbucket/key1" http://localhost:39999/api/v1/s3/testbucket/key2

HTTP/1.1 200 OK
Date: Wed, 02 Nov 2021 07:25:21 GMT
Content-Type: application/xml
Content-Length: 142
Server: Jetty(9.4.43.v20210629)

<CopyObjectResult>
    <LastModified>2009-10-28T22:32:00</LastModified>
    <ETag>"9b2cf535f27731c974343645a3985328"</ETag>
<CopyObjectResult>

Delete Single Objects

$ curl -i -X DELETE http://localhost:39999/api/v1/s3/testbucket/key1

HTTP/1.1 204 No Content
Date: Tue, 18 Jun 2019 21:31:27 GMT
Server: Jetty(9.2.z-SNAPSHOT)

$ curl -i -X DELETE http://localhost:39999/api/v1/s3/testbucket/key2

HTTP/1.1 204 No Content
Date: Tue, 18 Jun 2019 21:31:44 GMT
Server: Jetty(9.2.z-SNAPSHOT)

$ curl -i -X DELETE http://localhost:39999/api/v1/s3/testbucket/key3

HTTP/1.1 204 No Content
Date: Tue, 18 Jun 2019 21:31:58 GMT
Server: Jetty(9.2.z-SNAPSHOT)

$ curl -i -X DELETE http://localhost:39999/api/v1/s3/testbucket/testobject

HTTP/1.1 204 No Content
Date: Tue, 18 Jun 2019 21:32:08 GMT
Server: Jetty(9.2.z-SNAPSHOT)

Delete Multiple Objects

$ cat body.xml
<Delete xmlns="http://s3.amazonaws.com/doc/2006-03-01/">
   <Object>
      <Key>sample1.txt</Key>
   </Object>
   <Object>
      <Key>sample2.txt</Key>
   </Object>
   <Quiet>boolean</Quiet>
</Delete>
$ curl -i -X POST http://localhost:39999/api/v1/s3/testbucket?delete

HTTP/1.1 200 Ok
Date: Tue, 18 Jun 2019 21:32:08 GMT
Server: Jetty(9.2.z-SNAPSHOT)
<?xml version="1.0" encoding="UTF-8"?>
<DeleteResult xmlns="http://s3.amazonaws.com/doc/2006-03-01/">
  <Deleted>
    <Key>sample1.txt</Key>
  </Deleted>
  <Error>
  <Key>sample2.txt</Key>
  <Code>AccessDenied</Code>
  <Message>Access Denied</Message>
  </Error>
</DeleteResult>

Initiate a multipart upload

Since we deleted the testobject in the previous command, you have to create another testobject before initiating a multipart upload.

$ curl -i -X POST http://localhost:39999/api/v1/s3/testbucket/testobject?uploads

HTTP/1.1 200 OK
Date: Tue, 18 Jun 2019 21:32:36 GMT
Content-Type: application/xml
Content-Length: 133
Server: Jetty(9.2.z-SNAPSHOT)

<InitiateMultipartUploadResult><Bucket>testbucket</Bucket><Key>testobject</Key><UploadId>3</UploadId></InitiateMultipartUploadResult>

Note that the commands below related to multipart upload need the upload ID shown above, it's not necessarily 3.

Upload part

$ curl -i -X PUT 'http://localhost:39999/api/v1/s3/testbucket/testobject?partNumber=1&uploadId=3'

HTTP/1.1 200 OK
Date: Tue, 18 Jun 2019 21:33:36 GMT
ETag: "d41d8cd98f00b204e9800998ecf8427e"
Content-Length: 0
Server: Jetty(9.2.z-SNAPSHOT)

List parts

$ curl -i -X GET http://localhost:39999/api/v1/s3/testbucket/testobject?uploadId=3

HTTP/1.1 200 OK
Date: Tue, 18 Jun 2019 21:35:10 GMT
Content-Type: application/xml
Content-Length: 296
Server: Jetty(9.2.z-SNAPSHOT)

<ListPartsResult><Bucket>/testbucket</Bucket><Key>testobject</Key><UploadId>3</UploadId><StorageClass>STANDARD</StorageClass><IsTruncated>false</IsTruncated><Part><PartNumber>1</PartNumber><LastModified>2019-06-18T14:33:36.373Z</LastModified><ETag>""</ETag><Size>0</Size></Part></ListPartsResult>

Complete a multipart upload

$ curl -i -X POST http://localhost:39999/api/v1/s3/testbucket/testobject?uploadId=3

HTTP/1.1 200 OK
Date: Tue, 18 Jun 2019 21:35:47 GMT
Content-Type: application/xml
Content-Length: 201
Server: Jetty(9.2.z-SNAPSHOT)

<CompleteMultipartUploadResult><Location>/testbucket/testobject</Location><Bucket>testbucket</Bucket><Key>testobject</Key><ETag>"d41d8cd98f00b204e9800998ecf8427e"</ETag></CompleteMultipartUploadResult>

Abort a multipart upload

A non-completed upload can be aborted:

$ curl -i -X DELETE http://localhost:39999/api/v1/s3/testbucket/testobject?uploadId=3

HTTP/1.1 204 No Content
Date: Tue, 18 Jun 2019 21:37:27 GMT
Server: Jetty(9.2.z-SNAPSHOT)

Delete an empty bucket

$ curl -i -X DELETE http://localhost:39999/api/v1/s3/testbucket

HTTP/1.1 204 No Content
Date: Tue, 18 Jun 2019 21:38:38 GMT
Server: Jetty(9.2.z-SNAPSHOT)

Python S3 Client

Tested for Python 2.7.

Create a connection:

Please note you have to install boto package first.

$ pip install boto

import boto
import boto.s3.connection

conn = boto.connect_s3(
    aws_access_key_id = '',
    aws_secret_access_key = '',
    host = 'localhost',
    port = 39999,
    path = '/api/v1/s3',
    is_secure=False,
    calling_format = boto.s3.connection.OrdinaryCallingFormat(),
)

Authenticating as a user:

By default, authenticating with no access_key_id uses the user that was used to launch the proxy as the user performing the file system actions.

Set the aws_access_key_id to a different username to perform the actions under a different user.

Create a bucket

bucketName = 'bucket-for-testing'
bucket = conn.create_bucket(bucketName)

List all buckets owned by the user

Authenticating as a user is necessary to have buckets returned by this operation.

conn = boto.connect_s3(
    aws_access_key_id = 'testuser',
    aws_secret_access_key = '',
    host = 'localhost',
    port = 39999,
    path = '/api/v1/s3',
    is_secure=False,
    calling_format = boto.s3.connection.OrdinaryCallingFormat(),
)

conn.get_all_buckets()

PUT a small object

smallObjectKey = 'small.txt'
smallObjectContent = 'Hello World!'

key = bucket.new_key(smallObjectKey)
key.set_contents_from_string(smallObjectContent)

Get the small object

assert smallObjectContent == key.get_contents_as_string()

Upload a large object

Create a 8MB file on local file system.

$ dd if=/dev/zero of=8mb.data bs=1048576 count=8

Then use python S3 client to upload this as an object

largeObjectKey = 'large.txt'
largeObjectFile = '8mb.data'

key = bucket.new_key(largeObjectKey)
with open(largeObjectFile, 'rb') as f:
    key.set_contents_from_file(f)
with open(largeObjectFile, 'rb') as f:
    largeObject = f.read()

Get the large object

assert largeObject == key.get_contents_as_string()

Delete the objects

bucket.delete_key(smallObjectKey)
bucket.delete_key(largeObjectKey)

Initiate a multipart upload

mp = bucket.initiate_multipart_upload(largeObjectKey)

Upload parts

import math, os

from filechunkio import FileChunkIO

# Use a chunk size of 1MB (feel free to change this)
sourceSize = os.stat(largeObjectFile).st_size
chunkSize = 1048576
chunkCount = int(math.ceil(sourceSize / float(chunkSize)))

for i in range(chunkCount):
    offset = chunkSize * i
    bytes = min(chunkSize, sourceSize - offset)
    with FileChunkIO(largeObjectFile, 'r', offset=offset, bytes=bytes) as fp:
        mp.upload_part_from_file(fp, part_num=i + 1)

Complete the multipart upload

mp.complete_upload()

Abort the multipart upload

Non-completed uploads can be aborted.

mp.cancel_upload()

Delete the bucket

bucket.delete_key(largeObjectKey)
conn.delete_bucket(bucketName)