Lambda Memory Optimization

What this rule checks

Detects Lambda functions with suboptimal memory configuration.

How to fix it

1. 1Use AWS Lambda Power Tuning to find optimal memory
2. 2Consider cost vs performance tradeoffs

import * as lambda from 'aws-cdk-lib/aws-lambda';

// inside your Stack
new lambda.Function(this, 'Fn', {
  runtime: lambda.Runtime.NODEJS_22_X,
  handler: 'index.handler',
  code: lambda.Code.fromInline('exports.handler = async () => {};'),
  memorySize: 2048,
});

import * as lambda from 'aws-cdk-lib/aws-lambda';

// inside your Stack
new lambda.Function(this, 'Fn', {
  runtime: lambda.Runtime.NODEJS_22_X,
  handler: 'index.handler',
  code: lambda.Code.fromInline('exports.handler = async () => {};'),
  memorySize: 512,
});

CDK Insights pinpoints the exact file and line in your CDK source for every finding, so you can jump straight to the fix.

Affected resource types

Intentional? Suppress this finding

Sometimes a flag is deliberate — a genuinely public endpoint, say. You can dismiss lambda-memory-optimization and the reason is kept in the report, not silently hidden.

In .cdk-insights.json:

{
  "ignoreRules": [
    { "id": "lambda-memory-optimization", "reason": "Why this is intentional" }
  ]
}

Or inline in your CDK code:

Validations.of(scope).acknowledge({
  id: 'cdk-insights::lambda-memory-optimization',
  reason: 'Why this is intentional',
});

Use the rule ID lambda-memory-optimization shown above — not the CDK-* ID from SARIF / GitHub code scanning. To dismiss every finding on one construct instead, use ignorePaths. Suppression docs →

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