Anyone configured Pentaho 8 behind nginx?

Connecting via a load balancer https 443 (which looks after the certs) through on port 3000 to the default Pentaho 8080.

The Virtual host is set up to listen to 3000

location /pentaho/ {
proxy_pass http://<IP address>:8080/pentaho/;
proxy_http_version 1.1;
proxy_intercept_errors on;
}

So I can hit https://<external_IP>:443/penatho/
and I get a redirect to http://<internal_IP>>:3000/Login
(I can see this internally on the rproxy server as a wget on localhost:3000/pentaho get a 302 to :3000/pentaho/Login)

I can work around this....
Going direct to https://<external_IP>:443/penatho/Login
allows me to login ( the proxy_hhtp_version and proxy_interscept_errors seem to fix that)

But then I'm not able to Logout (which is another redriect)

Any ideas?