kevy-lua

The Lua scripting bridge for kevy. Wraps the in-house pure-Rust luna-core interpreter into the Redis EVAL / EVALSHA / SCRIPT command surface. Default dialect is Lua 5.1 (for Redis ecosystem compatibility); per-script opt-in to 5.2 / 5.3 / 5.4 / 5.5 via the shebang #!lua version=N. Includes pure-Rust cmsgpack and cjson standard libraries.

Why Lua 5.1 by default

Every real-world Redis Lua script in the ecosystem — BullMQ's command suite, Redlock, rate limiters, anything copied from the Redis docs — is written against PUC Lua 5.1.5 (the version Redis itself ships). A multi-dialect runtime that defaulted to 5.5 would break drop-in compatibility on day one.

#!lua version=5.3
-- now I can use integer math, goto, generic-for closures.
local count = redis.call("INCR", KEYS[1])  -- typed integer in 5.3+

This pattern extends Redis 7.0's #!lua name=... Functions shebang syntax with a new version= key. Scripts that don't carry a shebang continue to run on 5.1 exactly as they would on real Redis.

Audience

The bridge is consumed by the kevy server through the kevy-lua-host glue crate. End users invoke Lua via redis-cli EVAL or the equivalent in any Redis client library — see docs/lua.md.

Dependencies

This crate is one of three carved exemptions to the workspace's pure-Rust 0-dependency rule. It depends on luna-core — the in-house pure-Rust Lua runtime, itself zero-dependency on the luna side. The net effect on the kevy server's dependency graph is one transitive crate (luna-core).

License

MIT OR Apache-2.0, at your option.