Handle connexion problem with application

[clochix]

Some time, the application is running but the connexion with it is lost, for an unknown reason (ECONNRESET). It may be reseted only for a single request, or for every following request. So the user get a 504 error, while the application is running.

Maybe could we add to the error page an action to try to restart the application ?

[clochix]

In fact, this happens when connections between proxy and the application are not closed cleanly. They stay in CLOSE_WAIT state. By default, Node only allows five concurrent connections to the same origin, so when we reach this limit, the proxy become unable to communicate with the application, and the only solution seems to be to restart the proxy (restarting the application itself seems useless).

[nono]

See #235 and #238

[frankrousseau]

@clochix reopen this issue if the problem persists.