idempotency-middleware
v1.1.0
Published
Idempotency middleware for connect-like frameworks such as Express and Restana
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Idempotency Middleware
This middleware enables your API to handle requests idempotently, ensuring that the same operation is not executed multiple times. It is built on the concept of idempotence, a property in mathematics and computer science where certain operations can be repeated without changing the result. The middleware is compatible with Connect-like frameworks, such as Restana and Express.js.
Features
- Idempotent Request Handling: Ensures that duplicate requests with the same idempotency key are processed only once, preventing unintended side effects.
- Customizable Cache Integration: Supports any cache library that implements
get
andset
methods, allowing flexibility in your caching strategy. - Configurable Idempotency Key: Lets you define the key used to identify requests. By default, it uses the
x-request-id
header. - Adjustable TTL (Time-to-Live): Provides the ability to configure the expiration time for cache entries, balancing performance and resource usage.
- HTTP Method Support: Compatible with the following HTTP methods:
POST
,PUT
,PATCH
, andDELETE
.
Installation
npm install idempotency-middleware
Usage
import {idempotencyMiddleware} from 'idempotency-middleware'
import {createCache} from 'cache-manager'
import express, {type Request, type Response} from 'express'
import Keyv from 'keyv'
import {CacheableMemory} from 'cacheable'
const cache = createCache({
stores: [
new Keyv({
// for Redis support: https://www.npmjs.com/package/cache-manager#update-on-redis-and-ioredis-support
store: new CacheableMemory({ttl: 60000, lruSize: 5000}),
}),
],
})
const app = express()
app.use(
idempotencyMiddleware({
ttl: 5000, // 5 seconds
cache: {
get: async (key: string) => {
return cache.get(key)
},
set: async (key: string, value: any, options) => {
return cache.set(key, value, options?.ttl)
},
},
}),
)
app.post('/create', (req: Request, res: Response) => {
res.send('Resource created!')
})
app.listen(3000, () => {
console.log('Server is running on port 3000')
})
Calling the API
curl -X POST http://localhost:3000/create -H "x-request-id: 123" # 200 -> Resource created!
curl -X POST http://localhost:3000/create -H "x-request-id: 123" # 204
# after 5 seconds
curl -X POST http://localhost:3000/create -H "x-request-id: 123" # 200 -> Resource created!
Customizing idempotency key
By default, the middleware uses the x-request-id
header to identify the request. You can customize the key that will be used to identify the request by passing a custom idempotencyKeyExtractor
function to the middleware.
In production environments, it is recommended to use a combination of the
x-request-id
header and other unique identifiers such asservice-name
anduser-id
to ensure the key's uniqueness and prevent collisions.
app.use(
idempotencyMiddleware({
ttl: 5000,
idempotencyKeyExtractor: (req: Request) => {
return `${SERVICE_NAME}-${req.headers['x-custom-req-id']}`
},
//...,
}),
)
Security Considerations
The middleware is designed to operate in a trusted environment. If you plan to deploy it in an untrusted or partially trusted environment, take the following risks and mitigations into account:
1. Cache Flooding
An attacker could overwhelm the cache by sending a high volume of requests with unique x-request-id
values, exhausting resources and degrading performance.
Mitigation:
- Implement rate limiting and throttling mechanisms at the middleware or API gateway level.
- Set a maximum capacity for the idempotency cache, with a defined eviction policy (e.g., Least Recently Used (LRU) strategy).
- Monitor and log unusual traffic patterns to detect and respond to potential attacks promptly.
2. Identity Spoofing
An attacker could forge the x-request-id
header to impersonate another user's requests, potentially interfering with their operations.
Mitigation:
- Use a secure idempotency key that combines the
x-request-id
header with user-specific information, such as a hashed user identifier or session token. - Encrypt or digitally sign the
x-request-id
value to ensure its authenticity and prevent tampering.
General Recommendations
- Regularly audit the middleware's security practices and ensure compliance with your organization's security standards.
- Use HTTPS to protect the
x-request-id
header and prevent interception or tampering during transmission. - Test your middleware against common attack scenarios, such as denial-of-service (DoS) or injection attacks, to ensure robust protection.
License
See the LICENSE file for license rights and limitations (MIT).