Apache Hadoop Amazon Web Services support – Upgrade S3A to AWS SDK V2: Changelog

##### General

- Overview
- Single Node Setup
- Cluster Setup
- Commands Reference
- FileSystem Shell
- Compatibility Specification
- Downstream Developer's Guide
- Admin Compatibility Guide
- Interface Classification
- FileSystem Specification

##### Common

- CLI Mini Cluster
- Fair Call Queue
- Native Libraries
- Proxy User
- Rack Awareness
- Secure Mode
- Service Level Authorization
- HTTP Authentication
- Credential Provider API
- Hadoop KMS
- Tracing
- Unix Shell Guide
- Registry
- Async Profiler

##### HDFS

- Architecture
- User Guide
- Commands Reference
- NameNode HA With QJM
- NameNode HA With NFS
- Observer NameNode
- Federation
- ViewFs
- ViewFsOverloadScheme
- Snapshots
- Edits Viewer
- Image Viewer
- Permissions and HDFS
- Quotas and HDFS
- libhdfs (C API)
- WebHDFS (REST API)
- HttpFS
- Short Circuit Local Reads
- Centralized Cache Management
- NFS Gateway
- Rolling Upgrade
- Extended Attributes
- Transparent Encryption
- Multihoming
- Storage Policies
- Memory Storage Support
- Synthetic Load Generator
- Erasure Coding
- Disk Balancer
- Upgrade Domain
- DataNode Admin
- Router Federation
- Provided Storage

##### MapReduce

- Tutorial
- Commands Reference
- Encrypted Shuffle
- Pluggable Shuffle/Sort
- Distributed Cache Deploy
- Support for YARN Shared Cache

##### MapReduce REST APIs

- MR Application Master
- MR History Server

##### YARN

- Architecture
- Commands Reference
- Capacity Scheduler
- Fair Scheduler
- ResourceManager Restart
- ResourceManager HA
- Resource Model
- Node Labels
- Node Attributes
- Web Application Proxy
- Timeline Server
- Timeline Service V.2
- Writing YARN Applications
- YARN Application Security
- NodeManager
- Running Applications in Docker Containers
- Running Applications in runC Containers
- Using CGroups
- Secure Containers
- Reservation System
- Graceful Decommission
- Opportunistic Containers
- YARN Federation
- Shared Cache
- Using GPU
- Using FPGA
- Placement Constraints
- YARN UI2

##### YARN REST APIs

- Introduction
- Resource Manager
- Node Manager
- Timeline Server
- Timeline Service V.2

##### YARN Service

- Overview
- QuickStart
- Concepts
- Yarn Service API
- Service Discovery
- System Services

##### Hadoop Compatible File Systems

- Aliyun OSS
- Amazon S3
- Azure Blob Storage
- Azure Data Lake Storage
- Tencent COS
- Huaweicloud OBS
- VolcanoEngine TOS

##### Auth

- Overview
- Examples
- Configuration
- Building

##### Tools

- Hadoop Streaming
- Hadoop Archives
- Hadoop Archive Logs
- DistCp
- HDFS Federation Balance
- GridMix
- Rumen
- Resource Estimator Service
- Scheduler Load Simulator
- Hadoop Benchmarking
- Dynamometer

##### Reference

- Changelog and Release Notes
- Java API docs
- Unix Shell API
- Metrics

##### Configuration

- core-default.xml
- hdfs-default.xml
- hdfs-rbf-default.xml
- mapred-default.xml
- yarn-default.xml
- kms-default.xml
- httpfs-default.xml
- Deprecated Properties

# Upgrade S3A to AWS SDK V2: Changelog

Note: This document is not meant to be committed as part of the final merge, and instead just serves as a guide to help with reviewing the PR.

This document tracks changes to S3A during the upgrade to AWS SDK V2. Once the upgrade is complete, some of its content will be added to the existing document Upcoming upgrade to AWS Java SDK V2.

This work is tracked in HADOOP-18073.

## Contents

- Client Configuration
- Endpoint and region configuration
- List Object
- EncryptionSecretOperations
- GetObjectMetadata
- PutObject
- CopyObject
- MultipartUpload
- GetObject
- DeleteObject
- Select
- CredentialsProvider
- Auditing
- Metric Collection
- Exception Handling
- Failure Injection

### Client Configuration:

- We now have two clients, a sync S3 Client and an async S3 Client. The async s3 client is required as the select operation is currently only supported on the async client. Once we are confident in the current set of changes, we will also be exploring moving other operations to the async client as this could provide potential performance benefits. However those changes are not in the scope of this PR, and will be done separately.
- The createAwsConf method is now split into:

    createClientConfigBuilder // sets request timeout, user agent*
    createHttpClientBuilder* // sets max connections, connection timeout, socket timeout
    createProxyConfigurationBuilder // sets proxy config, defined in table below

The table below lists the configurations S3A was using and what they now map to.

SDK V1 | SDK V2
--- | ---
setMaxConnections | httpClientBuilder.maxConnections
setProtocol | The protocol is now HTTPS by default, and can only be modified by setting an HTTP endpoint on the client builder. This is done when setting the endpoint in getS3Endpoint()
setMaxErrorRetry | createRetryPolicyBuilder
setConnectionTimeout | httpClientBuilder.connectionTimeout
setSocketTimeout | httpClientBuilder.socketTimeout
setRequestTimeout | overrideConfigBuilder.apiCallAttemptTimeout
setSocketBufferSizeHints | Not supported
setSignerOverride | Not done yet
setProxyHost | proxyConfigBuilder.endpoint
setProxyPort | set when setting proxy host with .endpoint
setProxyUsername | proxyConfigBuilder.username
setProxyPassword | proxyConfigBuilder.password
setProxyDomain | proxyConfigBuilder.ntlmDomain, not supported in async client
setProxyWorkstation | proxyConfigBuilder.ntlmWorkstation, not supported in async client
setUserAgentPrefix | overrideConfigBuilder.putAdvancedOption(SdkAdvancedClientOption.USER_AGENT_PREFIX, userAgent);
addHeader | overrideConfigBuilder.putHeader
setUseThrottleRetries | not supported

### Endpoint and region configuration

Previously, if no endpoint and region was configured, fall back to using us-east-1. Set withForceGlobalBucketAccessEnabled(true) which will allow access to buckets not in this region too. Since the SDK V2 no longer supports cross region access, we need to set the region and endpoint of the bucket. The behaviour has now been changed to:

- If no endpoint is specified, use s3.amazonaws.com.
- When setting the endpoint, also set the protocol (HTTP or HTTPS)
- When setting the region, first initiate a default S3 Client with region eu-west-2. Call headBucket using this client. If the bucket is also in eu-west-2, then this will return a successful response. Otherwise it will throw an error with status code 301 permanently moved. This error contains the region of the bucket in its header, which we can then use to configure the client.

### List Object:

There is no way to paginate the listObject V1 result, we are doing this instead. We are trying to get pagination to listObject V1 in the SDK, but will have to use this workaround for now.

### EncryptionSecretOperations:

Two new methods have been added, `getSSECustomerKey` and `getSSEAwsKMSKey`. Previously SDK V1 had specific classes for these keys `SSECustomerKey` and `SSEAwsKeyManagementParams` . There are no such classes with V2, and things need to be set manually. For this reason, we simply just return keys as strings now. And will have to calculate and set md5’s ourselves when building the request.

### GetObjectMetadata:

- `RequestFactory.newGetObjectMetadataRequest` is now `RequestFactory.newHeadObjectRequestBuilder`.
- In `HeaderProcessing.retrieveHeaders()`, called by `getXAttrs()`, removed `maybeSetHeader(headers, XA_CONTENT_MD5, md.getContentMD5())` as S3 doesn’t ever actually return an md5 header, regardless of whether you set it during a putObject. It does return an `etag` which may or may not be an md5 depending on certain conditions. `getContentMD5()` is always empty, there does not seem to be a need to set this header.
- `RequestFactoryImpl.setOptionalGetObjectMetadataParameters` : Method has been removed and this logic has been moved to `RequestFactoryImpl.newHeadObjectRequestBuilder()`
- `RequestFactoryImpl.generateSSECustomerKey()` has been removed, and instead call `EncryptionSecretOperations.createSSECustomerKey` directly in `newHeadObjectRequestBuilder()`

### PutObject

- Previously, when creating the `putObjectRequest`, you would also give it the data to be uploaded. So it would be of the form `PutObjectRequest(bucket, key, file/inputstream)`, this is no longer the case. Instead, the data now needs to be passed in while making the `s3Client.putObject()` call. For this reason, the data is now part of the `S3AFileSystem.putObject(putObjectRequest, file, listener)` and `S3AFileSystem.putObjectDirect(putObjectRequest, putOptions, uploadData, isFile)`.
- `S3ADataBlocks`: Need to make this class public as it’s now used to pass in data to `putObjectDirect()`, sometimes from outside the package (`MagicCommitTracker` , `ITestS3AMiscOperations`).
- `ProgressableProgressListener`: You can no longer pass in the `Upload` while initialising the listener as `ProgressableProgressListener listener = new ProgressableProgressListener(this, key, upload, progress);` The upload is now only available after initialising the listener, since the listener needs to be initialised during creation of the Transfer Manager upload. Previously, you could create the listener after the starting the TM upload, and attach it.
- The `Upload` is now passed into the progress listener later, in `listener.uploadCompleted(uploadInfo.getFileUpload());`.
- `UploadInfo`: Previously, since the data to be uploaded was part of `putObjectRequest`, the transfer manager only returned a single `Upload` type, which could be used to track the upload. Now, depending on the upload type (eg: File or InputStream), it returns different types. This class has been updated to return FileUpload info, as it’s only ever used for file uploads currently. It can be extended to store different transfer types in the future.
- `WriteOperationHelper.createPutObjectRequest()`: Previously the data to be uploaded was part of `PutObjectRequest`, and so we required two methods to create the request. One for input streams and one for files. Since the data to be uploaded is no longer part of the request, but instead an argument in `putObject` , we only need one method now.
- `WriteOperationHelper.newObjectMetadata()`: This method has been removed, as standard metadata, instead of being part of the `ObjectMetadata`, is now just added while building the request, for example `putObjectRequestBuilder.serverSideEncryption().`
- `RequestFactory`: Similar to WriteOperationHelper, there is now a single putObjectRequest, and `newObjectMetadata` has been removed. Instead, all standard metadata is now set in the new method `buildPutObjectRequest`.
- `RequestFactoryImpl.newObjectMetadata()`: Previously, object metadata was created using `newObjectMetadata()` and passed into the `newPutObjectRequest()` call. This method has been removed, as standard metadata, instead of being part of the `ObjectMetadata`, is now just added while building the request, in `putObjectRequestBuilder.serverSideEncryption().` Content length and content encoding set in this method is now set in `buildPutObjectRequest()` , and SSE is set in `putEncryptionParameters()`.
- `RequestFactoryImpl.maybeSetMetadata()` : was a generic method to set user metadata on object metadata. user metadata now gets set on the request builder, so method has been removed.
- `RequestFactoryImpl.setOptionalPutRequestParameters()` : Method has been removed, and this logic has been moved to `putEncryptionParameters()` .

### CopyObject

- `RequestFactoryImpl.buildPutObjectRequest` : Destination metadata is no longer built using `newObjectMetadata()` and instead set on the request builder. The logic has a couple of differences:
- content encoding is set in `buildCopyObjectRequest`, the `if (contentEncoding != null && !isDirectoryMarker)` can just be `if (contentEncoding != null)` for copy, as for this `isDirectoryMarker` was always false.
- contentLength is not set, as this is a system defined header, and copied over automatically by S3 during copy.
- `HeaderProcessing.cloneObjectMetadata`: This was previously also setting a lot of system defined metadata, eg: `setHttpExpiresDate` and `setLastModified`. These have been removed as they are set by S3 during the copy. Have tested, and can see they are set automatically regardless of the metadataDirective (copy or replace).
- `RequestFactoryImpl. copyEncryptionParameters()` : Due to the changes in `EncryptionSecretOperations`, source and destination encryption params have to be set manually.

### MultipartUpload

- `RequestFactoryImpl.newObjectMetdata()` : Metadata is now set on the request builder. For MPU, only content encoding needs to be set, as per per previous behaviour. Encryption params are set in `multipartUploadEncryptionParameters`.

### GetObject

- Previously, GetObject returned a `S3Object` response which exposed its content in a `S3ObjectInputStream` through the `getObjectContent()` method. In SDK v2, the response is directly a `ResponseInputStream<GetObjectResponse>` with the content, while the `GetObjectResponse` instance can be retrieved by calling `response()` on it.
- The above change simplifies managing the lifetime of the response input stream. In v1, `S3AInputStream` had to keep a reference to the `S3Object` while holding the wrapped `S3ObjectInputStream`. When upgraded to SDK v2, it can simply wrap the new `ResponseInputStream<GetObjectResponse>`, which handles lifetime correctly. Same applies to `SDKStreamDrainer`. Furthermore, the map in `S3ARemoteObject` associating input streams and `S3Object` instances is no longer needed.
- The range header on a `GetObject` request is now specified as a string, rather than a `start`-`end` pair. `S3AUtils.formatRange` was introduced to format it.

### DeleteObject

In SDK v1, bulk delete would throw a `com.amazonaws.services.s3.model.MultiObjectDeleteException` in case of partial failure. In v2, instead, it returns a `DeleteObjectsResponse` containing a list of errors. A new `MultiObjectDeleteException` class was introduced in `org.apache.hadoop.fs.s3a` and is thrown when appropriate to reproduce the previous behaviour. * `MultiObjectDeleteSupport.translateDeleteException` was moved into `MultiObjectDeleteException`. * `ObjectIdentifier` replaces DeleteObjectsRequest.KeyVersion.

### Select

In SDK v2, Handling of select requests has changes significantly since SelectObjectContent is only supported on the new async S3 client. In previous versions, the response to a SelectObjectContent request exposed the results in a `SelectRecordsInputStream`, which S3A could wrap in `SelectInputStream`. In v2, instead, the response needs to be handled by an object implementing `SelectObjectContentResponseHandler`, which can receive an async publisher of the “events” returned by the service (`SdkPublisher<SelectObjectContentEventStream>`).

In order to adapt the new API in S3A, three new classes have been introduced in `org.apache.hadoop.fs.s3a.select`:

- `SelectObjectContentHelper`: wraps the `selectObjectContent()` call, provides a custom response handler to receive the response, and exposes a `SelectEventStreamPublisher`.
- `SelectEventStreamPublisher`: a publisher of select event stream events, which handles the future returned by the select call and wraps the original publisher. This class provides a `toRecordsInputStream()` method which returns an input stream containing the results, reproducing the behaviour of the old `SelectRecordsInputStream`.
- `BlockingEnumeration`: an adapter which lazily requests new elements from the publisher and exposes them through an `Enumeration` interface. Used in `SelectEventStreamPublisher.toRecordsInputStream()` to adapt the event publisher into an enumeration of input streams, eventually passed to a `SequenceInputStream`. Note that the “lazy” behaviour means that new elements are requested only on `read()` calls on the input stream.

### CredentialsProvider

- All credential provider classes implemented in Hadoop now implement V2’s `AwsCredentialProvider`
- New adapter class `org.apache.hadoop.fs.s3a.adapter.V1ToV2AwsCredentialProviderAdapter` has been added. This converts SDK V1 credential providers to SDK V2’s which implement `AwsCredentialsProvider`.
- `AWSCredentialProviderList` also implements `AwsCredentialProvider`. But keeps existing constructors and add methods for V1 credential providers, and wraps V1 cred providers in the adapter here. This means that custom binding classes in delegation tokens, as well as any custom credential providers will continue to work.
- Added a new `getCredentials()` method in `AWSCredentialProviderList`, which ensured that custom binding classes which are calling `AWSCredentialProviderList.getCredentials()`, continue to work.
- The following values `fs.s3a.aws.credentials.provider` are mapped: as `com.amazonaws.auth.EnvironmentVariableCredentialsProvider`, then map it to V2’s

`fs.s3a.aws.credentials.provider` value | Mapped to
--- | ---
`com.amazonaws.auth.EnvironmentVariableCredentialsProvider` | `software.amazon.awssdk.auth.credentials.EnvironmentVariableCredentialsProvider`
`com.amazonaws.auth.EC2ContainerCredentialsProviderWrapper` | `org.apache.hadoop.fs.s3a.auth.IAMInstanceCredentialsProvider`
`com.amazonaws.auth.`InstanceProfileCredentialsProvider`` | `org.apache.hadoop.fs.s3a.auth.IAMInstanceCredentialsProvider`

### Auditing

The SDK v2 offers a new `ExecutionInterceptor` interface which broadly replaces the `RequestHandler2` abstract class from v1. Switching to the new mechanism in S3A brings:

- Simplification in `AWSAuditEventCallbacks` (and implementors) which can now extend `ExecutionInterceptor`
- “Registering” a Span with a request has moved from `requestCreated` to `beforeExecution` (where an `ExecutionAttributes` instance is first available)
- The ReferrerHeader is built and added to the http request in `modifyHttpRequest`, rather than in `beforeExecution`, where no http request is yet available
- Dynamic loading of interceptors has been implemented to reproduce previous behaviour with `RequestHandler2`s. The AWS SDK v2 offers an alternative mechanism, described here under “Interceptor Registration”, which could make it redundant.

In the Transfer Manager, `TransferListener` replaces `TransferStateChangeListener`. S3A code has been updated and `AuditManagerS3A` implementations now provide an instance of the former to switch to the active span, but registration of the new listeners is currently commented out because it causes an incompatibility issue with the internal logger, resulting in `NoSuchMethodError`s, at least in the current TransferManager Preview release.

### Metric Collection

`AwsStatisticsCollector` has been updated to implement the new `MetricPublisher` interface and collect the metrics from a `MetricCollection` object. The following table maps SDK v2 metrics to their equivalent in v1:

v2 Metrics | com.amazonaws.util.AWSRequestMetrics.Field | Comment
--- | --- | ---
CoreMetric.RETRY_COUNT | HttpClientRetryCount
CoreMetric.RETRY_COUNT | RequestCount | always HttpClientRetryCount+1
HttpMetric.HTTP_STATUS_CODE with HttpStatusCode.THROTTLING | ThrottleException | to be confirmed
CoreMetric.API_CALL_DURATION | ClientExecuteTime
CoreMetric.SERVICE_CALL_DURATION | HttpRequestTime
CoreMetric.MARSHALLING_DURATION | RequestMarshallTime
CoreMetric.SIGNING_DURATION | RequestSigningTime
CoreMetric.UNMARSHALLING_DURATION | ResponseProcessingTime | to be confirmed

Note that none of the timing metrics (`*_DURATION`) are currently collected in S3A.

### Exception Handling

The code to handle exceptions thrown by the SDK has been updated to reflect the changes in v2:

- `com.amazonaws.SdkBaseException` and `com.amazonaws.AmazonClientException` changes:
- These classes have combined and replaced with `software.amazon.awssdk.core.exception.SdkException`.
- `com.amazonaws.SdkClientException` changes:
- This class has been replaced with `software.amazon.awssdk.core.exception.SdkClientException`.
- This class now extends `software.amazon.awssdk.core.exception.SdkException`.
- `com.amazonaws.AmazonServiceException` changes:
- This class has been replaced with `software.amazon.awssdk.awscore.exception.AwsServiceException`.
- This class now extends `software.amazon.awssdk.core.exception.SdkServiceException`, a new exception type that extends `software.amazon.awssdk.core.exception.SdkException`.

See also the SDK changelog.

### Failure Injection

While using the SDK v1, failure injection was implemented in `InconsistentAmazonS3CClient`, which extended the S3 client. In SDK v2, reproducing this approach would not be straightforward, since the default S3 client is an internal final class. Instead, the same fault injection strategy is now performed by a `FailureInjectionInterceptor` (see ExecutionInterceptor) registered on the default client by `InconsistentS3CClientFactory`. `InconsistentAmazonS3CClient` has been removed. No changes to the user configuration are required.