map $http_upgrade $connection_upgrade {
    default upgrade;
    '' close;
}

map $http_upgrade $upgrade_request {
    default 1;
    '' 0;
}

server {
    listen 80;
    server_name _;
    root /usr/share/nginx/html;
    index index.html;

    location / {
        error_page 418 = @websocket;

        if ($upgrade_request = 1) {
            return 418;
        }

        try_files $uri $uri/ /index.html;
    }

    location @websocket {
        proxy_pass http://broker:9001;
        proxy_http_version 1.1;
        proxy_read_timeout 1d;
        proxy_send_timeout 1d;
        proxy_set_header Host $host;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection $connection_upgrade;
    }
}
