You need to configure Nginx work with cgi scripts.
Add to munin.conf this parameters:
It means that html and graphs will be generated by cgi scripts.
Next, confugure your nginx server config:
And then start fcgi sockets:
To debug, just add
-n parameter. Pleast be aware, in that way your nginx server must work by www-data user. If not, change your configuration or change username and group in the commands.
Here official manual, there is some difference. Instead of
cgi-bin I wrote
munin-cgi, don’t know why, but on that works for me.