aws/aws-cdk

elasticache-alpha: dailyBackupTime field uses misleading Schedule type

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#36981 opened on Feb 12, 2026

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@aws-cdk/aws-schedulerbugeffort/smallgood first issuep2

Description

Describe the bug

The alpha elasticache module uses events.Schedule for dailyBackupTime. The expected elasticache type in the Cfn is just a time of day string HH:MM, but schedule is essentially a full cron interface leading to user potentially configuring a bunch of things that are irrelevant to the field.

https://github.com/aws/aws-cdk/blob/67f09c04ad860ff25494e1e76071c304adcf39b4/packages/%40aws-cdk/aws-elasticache-alpha/lib/serverless-cache.ts#L84

Proposal: Create a new helper type to specify time of day or revert back to expect a string on this field with validation in the construct that it matches expected string format.

Regression Issue

  • Select this option if this issue appears to be a regression.

Last Known Working CDK Library Version

No response

Expected Behavior

Not to use Schedule type for this field

Current Behavior

uses overly broad Schedule type

Reproduction Steps

n/a

Possible Solution

No response

Additional Information/Context

No response

AWS CDK Library version (aws-cdk-lib)

n/a

AWS CDK CLI version

n/a

Node.js Version

n/a

OS

n/a

Language

TypeScript

Language Version

No response

Other information

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Contributor guide

Tech stack
typescript
Domain
backendcloudinfrastructure
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
TypeScript basicsAWS CDK constructs
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
70
Research direction
The issue identifies a specific file: packages/@aws cdk/aws elasticache alpha/lib/serverless cache.ts line 84 where dailyBackupTime is typed as events.Schedule. The expected behavior is to use a simple time string (HH:MM) with validation. To implement, either create a new helper type for time of day or revert to string with regex validation. Review existing CDK patterns for similar fields, and check for any existing PRs or discussions. The fix is localized and well defined.