location / {
    proxy_pass http://127.0.0.1:5000;
    proxy_http_version 1.1;
    proxy_set_header Upgrade $http_upgrade;
    proxy_set_header Connection $connection_upgrade;
    proxy_set_header Host $host;
    proxy_cache_bypass $http_upgrade;
    proxy_read_timeout 3600s;
}

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