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AWS Lambda

Note

Max AWS Lambda spending rate: $1200 / hour / region

Usage

Preferred implementation leverages CostLimit aspect.

Alternatively, you can simply replace your Function native CDK import statement by this package exported Function construct.

- import { Function } from "@aws-cdk-lib/aws-lambda";
+ import { Function } from "@revant-io/cdk-cost-limit";

The Function construct accepts the exact same props at the AWS CDK Function construct (refer to the AWS CDK dedicated documentation for a list of all supported props). In addition to those native props, it accepts the following:

Name Type Description
budget? number The monthly budget limit for this specific resource, specified in $US cents

Example

import { Function } from "@revant-io/cdk-cost-limit";

const fn = new Function(this, "MyFunction", {
  /* The budget allocated to this resource in $US cents.
   * For exemple, if you want to set a budget of $1,00
   * for a specific Lambda function, you should used
   * a value of 100 for this prop.
   */
  budget: 100,
});

By default, if budget is not specified, an unlimited budget (Function normal behavior) is used.

How it works

Lambda architecture

Disabling strategy

Lambda functions are disabled using the reserved concurrency parameter. The value for this parameter is set to 0 when a specific function is disabled.

What is deployed?

Budget update and control is handled by an extension packaged in 2 layers (one for x86 architecture and one for ARM architecture). This extension starts a local endpoint and register for telemetry events from Lambda service. It listen to platform.report events, containing billed duration and memory configuration informations. Budget informations (address and amout) are accessible by the extension using environment variables.

Manually restore

In order to reset Function that have been disabled by a budget, you need to remove the reserved concurrency.

aws lambda delete-function-concurrency --function-name <functionName>

If your function already had a reserved concurrency as specified in your CDK code base like so

new Function(scope, "MyFunction", {
  //...
  reservedConcurrentExecutions: 23, // your initial reserved concurrency
  //...
});

you can reset it back to the initial value using the corresponding update-function-concurrency API

aws lambda put-function-concurrency --function-name <functionName> --reserved-concurrent-executions <initialReservedConcurrencyValue>