Unix sockets work but are not documented

The following configuration using a unix socket as the current peer works, but it is not documented.

Adding the line:
local ok, err = balancer.set_current_peer('some_unix_socket_name');
would suffice

http {
upstream backend {
server 0.0.0.1; # just an invalid address as a place holder
balancer_by_lua_block {
local balancer = require "ngx.balancer"
local suname = 'unix:/tmp/nginx_socket';
local ok, err = balancer.set_current_peer(suname);
if not ok then
ngx.log(ngx.ERR, "failed to set the current peer: ", err)
return ngx.exit(500)
end
}
}
server {
listen 8080;
location /S/ {
proxy_pass http://backend/S/;
}
}
server {
listen unix:/tmp/nginx_socket;
location /S/__debug {
content_by_lua_file ./locations/debug;
}
}

Start by locating the documentation entry point for the ngx.balancer.set_current_peer API. Use the Unix-socket configuration shown in the issue as the example, and consider the documentation complete when it explains that a unix socket name can be passed as the current peer with the required format.