Flink web ui authentication using nginx

[Kumar Bolar, Harshith]

Hi all,

I'm trying to add authentication to the web dashboard using `nginx`. Flink's 
`rest.port` is set to `8081`, connection to this port is disabled by firewall. 
I'm using `nginx` to listen to requests on port 8080 and redirect to port 8081 
them with username/password authentication (Port 8080 is open).

This is what the server block looks like in `nginx.conf`.

server {
        listen       8080;
        server_name  localhost;
        include /etc/nginx/default.d/*.conf;
        location / {
        proxy_pass https://localhost:8081;
            auth_basic           "Administrator's Area";
            auth_basic_user_file /etc/apache2/.htpasswd;
        }
        error_page 404 /404.html;
            location = /40x.html {
        }
        error_page 500 502 503 504 /50x.html;
            location = /50x.html {
        }
    }


The port redirection is working fine but there are a couple of issues. When I 
go to the inactive job manager's UI, redirection to the active job manager is 
not happening. And when I try submitting a job from the UI, the upload gets 
stuck at "Saving". I’m using Flink 1.7.2

Has anyone successfully set up web UI authentication on Flink complete with HA 
mode? Any clues would be greatly appreciated.

Thanks,
Harshith