Works:
root@bionic-maas:~# curl -I http://$api_host:5240/MAAS/ HTTP/1.1 302 Found Server: TwistedWeb/17.9.0 Date: Wed, 13 Mar 2019 19:21:02 GMT Content-Type: text/html; charset=utf-8 Location: /MAAS/accounts/login/?next=%2FMAAS%2F Content-Length: 0 Vary: Cookie
Works:
root@bionic-maas:~# curl -I http:// $api_host: 5240/MAAS/ login/? next=%2FMAAS% 2F
HTTP/1.1 302 Found
Server: TwistedWeb/17.9.0
Date: Wed, 13 Mar 2019 19:21:02 GMT
Content-Type: text/html; charset=utf-8
Location: /MAAS/accounts/
Content-Length: 0
Vary: Cookie