RateLimiter plugin

The RateLimiter prefix plugin intercepts calls to a rate-limiter adapter and transparently prefixes all rate-limiter keys with a configurable string. This enables logical key namespacing without modifying the adapter implementation.

Use cases

• Multi-tenant rate limiting — Prefix rate-limiter keys with a tenant identifier to apply separate rate limits per tenant
• Endpoint scoping — Organize rate limits by API endpoint or route prefix
• Environment isolation — Separate development, staging, and production rate limit state
• User tier differentiation — Prefix keys with a tier identifier (e.g., "free:", "premium:") to apply different rate limits

How it works

The withRateLimiterPrefix function returns a PluginFn that calls enhance on each adapter method that accepts a rate-limiter key. When an enhanced method is invoked, the plugin intercepts the call, prepends the configured prefix to the key argument, and forwards the modified arguments to the original method.

The plugin prefixes keys for the following methods:

Method	Key argument	Pattern
getState	Second argument (key)	prefix + key
reset	Second argument (key)	prefix + key
updateState	Second argument (key)	prefix + key

Every method on the IRateLimiterAdapter that operates on a specific rate-limiter key is prefixed.

Usage

import { withPlugin } from "@daiso-tech/core/middleware";
import { MemoryRateLimiterStorageAdapter } from "@daiso-tech/core/rate-limiter/memory-rate-limiter-storage-adapter";
import { DatabaseRateLimiterAdapter } from "@daiso-tech/core/rate-limiter/database-rate-limiter-adapter";
import { withRateLimiterPrefix } from "@daiso-tech/core/rate-limiter/plugins";

const adapter = new DatabaseRateLimiterAdapter({
    adapter: new MemoryRateLimiterStorageAdapter(),
});

// Apply the prefix plugin
const prefixedAdapter = withPlugin(
    adapter,
    withRateLimiterPrefix("tenant-42:"),
);

// The key "api:login" is automatically prefixed to "tenant-42:api:login"
const state = await prefixedAdapter.getState(context, "api:login");

Using with RateLimiterFactory

The plugin can be applied directly to the adapter passed to the RateLimiterFactory constructor:

import { RateLimiterFactory } from "@daiso-tech/core/rate-limiter";
import { DatabaseRateLimiterAdapter } from "@daiso-tech/core/rate-limiter/database-rate-limiter-adapter";
import { withPlugin } from "@daiso-tech/core/middleware";
import { withRateLimiterPrefix } from "@daiso-tech/core/rate-limiter/plugins";

const adapter = new DatabaseRateLimiterAdapter({ ... });
const prefixedAdapter = withPlugin(adapter, withRateLimiterPrefix("free-tier:"));

const factory = new RateLimiterFactory({
    adapter: prefixedAdapter,
});

Before/after behavior

Before — Rate-limiter keys are used as-is:

adapter.getState(context, "api:login")
→ checks rate limit for "api:login"

After — Rate-limiter keys are automatically prefixed:

adapter.getState(context, "api:login")
→ checks rate limit for "tenant-42:api:login"

info

For more information about the withPlugin function and applying plugins to adapters, see the Middleware plugin documentation.