Introducing Dynamic Rate-Limits for Upstash Ratelimit

Upstash has introduced a new feature called dynamic limits to its Ratelimit service, allowing users to adjust rate limits at runtime rather than redeploying applications or swapping rate limiter instances. This new feature leverages Redis to enable instant global changes to rate limits for serverless functions, with the ability to override default settings for all users. Dynamic limits work with fixedWindow, slidingWindow, and tokenBucket algorithms, but not with cachedFixedWindow due to its reliance on locally cached results. The update is particularly useful for managing traffic spikes and testing new limits without redeployment. Users should be cautious with the ephemeral cache, which can delay the application of increased limits until the cache resets. The feature currently supports single-region rate limiters, with plans to expand to multi-region in future releases, promising no additional performance impact as it maintains a single Redis call per request check.