aws-kinesis: support maximum record size on Stream

[badmintoncryer]

Describe the feature

MaxRecordSizeInKiB is supported by the underlying L1 AWS::Kinesis::Stream but missing from the L2 StreamProps in aws-cdk-lib/aws-kinesis.

Kinesis Data Streams raised the maximum size of a single record from 1 MiB to 10 MiB in October 2025.

Use Case

Workloads that intermittently emit payloads larger than 1 MiB (IoT telemetry batches, CDC records, generative AI payloads) no longer need to split records across a side channel. Configuring this from CDK currently requires an escape hatch:

const stream = new kinesis.Stream(this, 'MyStream');
(stream.node.defaultChild as kinesis.CfnStream).maxRecordSizeInKiB = 10240;

Proposed Solution

Add optional maxRecordSize?: Size to StreamProps and pass it through to the L1 MaxRecordSizeInKiB.

new kinesis.Stream(this, 'MyLargeRecordStream', {
  maxRecordSize: Size.mebibytes(10),
});

Size rather than a raw number, so the unit is carried by the type. Same as ephemeralStorageSize in aws-lambda and provisionedThroughputPerSecond in aws-efs.

Other Information

WarmThroughputMiBps is also missing from this L2. Different constraints, so I will raise it separately.

Acknowledgements

• I may be able to implement this feature request
• This feature might incur a breaking change

AWS CDK Library version (aws-cdk-lib)

2.267.0

AWS CDK CLI version

2.1131.0 (build 1e9a1e1)

Node.js Version

v20.19.2

OS

macOS 14.6.1

Language

TypeScript

[pahud]

Thanks for the well-scoped request — and for opening #38720 alongside it. I reproduced the gap on your reported aws-cdk-lib@2.267.0: maxRecordSize fails TypeScript compilation because it's absent from StreamProps, while the generated L1 CfnStream already supports maxRecordSizeInKiB. Current main is unchanged:

aws-cdk/packages/aws-cdk-lib/aws-kinesis/lib/stream.ts

Lines 964 to 975 in 604ac23

	this.stream = new CfnStream(this, 'Resource', {
	name: this.physicalName,
	retentionPeriodHours,
	shardCount,
	streamEncryption,
	desiredShardLevelMetrics: props.shardLevelMetrics,
	...(props.streamMode !== undefined
	? {
	streamModeDetails: { streamMode: props.streamMode },
	}
	: undefined),
	});

Until the L2 prop ships, you don't need the raw escape hatch — the generated property mixin covers this. I verified it synthesizes MaxRecordSizeInKiB correctly on 2.267.0:

import { aws_kinesis as kinesisMixins } from '@aws-cdk/cfn-property-mixins';

const stream = new kinesis.Stream(this, 'Stream');
stream.with(new kinesisMixins.CfnStreamPropsMixin({
  maxRecordSizeInKiB: 10240,
}));

On the PR itself: from my view it's in good shape — Size-typed prop, KiB-based validation with a token guard (validating in KiB rather than MiB is the right call, since Size.kibibytes(1536) is legal but not a whole number of mebibytes), boundary/token/absent unit tests, a deploy-verified integ test covering both capacity modes, README + rosetta fixture updates, and the full check suite is green. It appears to only need a rebase onto main and a maintainer review.

Thank you for filling the gap.