HAProxy also has Lua support. The general answer here, is no, I don't think you can do much in HAProxy that you can't do with OpenResty, but with HAProxy you g

HAProxy also has Lua support. The general answer here, is no, I don't think you can do much in HAProxy that you can't do with OpenResty, but with HAProxy you generally don't have to pay the overhead of Lua (and HAProxy tends to be very well optimized, so the difference can be significant at high throughput of requests / bytes).