container-director/director.conf

server {
    listen       8080;
    server_name  _;

    resolver 127.0.0.11 valid=1s;

    location / {
        proxy_pass http://${CONTAINER_PREFIX}-$http_x_forwarded_preferred_username:${CONTAINER_PORT};
        proxy_set_header Host ${CONTAINER_PREFIX}-$http_x_forwarded_preferred_username;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection upgrade;
        proxy_set_header Accept-Encoding gzip;
        error_page 502 = @spawner;
    }
    
    location @spawner {
        proxy_pass http://${SPAWNER_HOST}:8080$uri;
    }
}