A Redis-backed rate limiter, based on the leaky-bucket algorithm. This repository provides the Lua script for use with EVAL, to allow libraries across multiple languages to utilize the same script and data format. It was extracted from redis-bucket, which can be referenced for a more detailed description and validation of correctness.
In order to make changes to this script, Node.js and npm must be installed to generate the minified script and SHA1 hashes used by EVALSHA.
The script takes a single key, along with arguments in the following order:
cost flow burst [flow burst]*
cost is the cost of the current action. It is followed by flow/burst pairs
defining the buckets being limited against; flow is specified in cost per
second, and burst in total cost.
Buckets are stored in the same order as they are provided, so this ordering must
be consistent. The recommended ordering is one of strictly increasing flow and
strictly decreasing burst. This ordering also filters out any buckets which
are larger than any other buckets in both values, which makes them superfluous
(since the smaller limit will always be more restrictive).
The script returns an array with the following values:
allowed, value, index
allowed is either 1 (allow) or 0 (deny). value is a stringified number
representing either the remaining free capacity (if allowed) or the running
denied capacity (if denied). index is the numeric index of the bucket with the
lowest remaining capacity (which will be the cause of the limiting if denied).
This project has adopted the Microsoft Open Source Code of Conduct. For more information see the Code of Conduct FAQ or contact [email protected] with any additional questions or comments.