I was trying to figure out how the webserver in LuCI works, and realized that there are two (or maybe three) web servers mentioned in the OpenWrt documentation. They are:
uhttpd
lighttpd
(maybe) Busybox
I believe that uhttpd is the default web server for the LuCI GUI in 19.07. But I see that lightttpd (and a zillion of its packages) are also installed by default in 19.07. Update: That last sentence is wrong, wrong, wrong. lighttpd is not installed...
How can I tell which is running? What's their relationship? Is lighttpd ever required? Thanks.
Correct, uhttpd is the default server and lighttpd is not required. Optionally, uhttpd can be substituted with any CGI-capable server (apache, lighttpd) or with nginx + a fastCGI wrapper