Hi Thomas,
 
Displaying the notification and opening a screen with detail of an alert
would be good.

Yep, it will be there.
 
I am not sure about the authentication flow, user should first
authenticate and then somewhere in the interface he should be able to
switch tenant (*if* he has several). I guess a good place would be the
top entry of the side menu.

Sorry for not making it clear — it will be done almost exactly as you are saying. User will be available to add multiple servers and tenants. It will be done via the same flow. There is a spinner at the top of the drawer menu which will allow to select the necessary one. Basically it will be very similar to Google Mail and Google Play apps.
 
Environment can be ignored for now, it won't be in the admin console
for a while. In the end, I think you could end up with a single screen,
with server Host+Port, login name and Password.

Actually I already switched to OAuth, so there will be host input, port input, tenants spinner and "Authorize" button.
 
I don't think we need the metric table, graph are way more useful.

Not everything can be presented via a graph — HTTP status codes for example.
 
Resources at the moment are URLs or Servers. You would need to list
them.

It is already in the mockup — the resources screen just below the screen with a drawer. If I understood you correctly of course.

Thanks!
Artur.