lua-resty-resolver

A pure lua DNS resolver that supports:

Caching DNS lookups according to upstream TTL values
Caching DNS lookups directly from the master (i.e. don't replicate DNS queries per worker thread)
Support for DNS-based round-robin load balancing (e.g. multiple A records for a single domain)
Low cache contention via local worker cache (i.e. workers sync from the master using a randomized delay to avoid contention)
Optional stale results to smooth over DNS availability issues
Configurable min / max TTL values
Sensible security (e.g. don't allow potentially harmful results such as 127.0.0.1)