Documentation about Regex Syntax


What’s the regex syntax used by HaProxy ACL, is that somehow HaProxy specific ore is it using a specific library. I’m asking because each programming language is using their own falvour of regular expressions and I wonder what’s being used by ACL in HaProxy.


Which regex engine is used can been seen in the haproxy -vv output (“haproxy -vv | grep PCRE”).

Usually that is PCRE. Since haproxy 1.8 there is also support for PCRE2 and we have a fallback to libc’s RE engine in case haproxy is not linked against PCRE.


Thanks a lot @lukastribus