No, that is not meant to fire up a socket on its own.
I’d be wary of copying parts from other people’s configuration without understanding why they did what they did. In this case, in the other thread the user added an extra process, specifically to listen on -status.sock:
Lastly, the problem really is just to do with the FastCGI variables. Usually for PHP we rely on the php preset which sets a few of them for us, but it only really works well on index and *.php file requests.
Since want to specifically send every request under a certain base path to fastcgi, we need to specify the script name, exactly like you did on the command line. This example Caddyfile works for me.
:2015 {
fastcgi /status :9000 {
env SCRIPT_NAME /status
}
}