In programming, idempotency refers to the capacity of an application or component to identify repeated events and prevent duplicated, inconsistent, or lost data. Making your AWS Lambda function idempotent requires designing your function logic to treat duplicated events correctly.
Idempotent function logic can help to reduce the following issues:
- Unnecessary API calls
- Code processing time
- Data inconsistency
- Throttles
- Latency
Middy is a middleware framework that allows you to simplify your AWS Lambda code when using Node.js. This middleware aims to replicate the AWS Lambda Powertools idempotency utility built in Python.
Other sources to learn about idempotency:
Other idempotency projects for Middy:
- middy-idempotent - Uses ioredis and Upstash
To install this middleware you can use NPM:
npm install --save middy-idempotencyRequires @middy/core >= 2.0.0
middy-idempotency requires a persistence store to save the current status of an AWS Lambda execution. Currently, only DynamoDB is supported as a persistence store.
const middy = require('@middy/core')
const idempotency = require('middy-idempotency')
const DynamoDbPersistenceLayer = require('middy-idempotency/persistence/dynamodb')
const processEvent = async (event, context) => {
return {
statusCode: 200,
body: JSON.stringify({
message: 'hello world',
}),
}
}
const dynamodb = new DynamoDbPersistenceLayer({
tableName: 'myIdempotencyTable',
})
const lambdaHandler = middy(processEvent).use(idempotency({ PersistenceStore: dynamodb }))
module.exports = { lambdaHandler }- Improve documentation
- Add in-memory cache
- Add payload validation
- Add more advanced customization
- Add other persistence stores (i.e. Redis)
- Convert to TypeScript for type checking
Feel free to fork and make a PR for any enhancements or new features!
Copyright (c) 2021 Ryan Toler
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