Is there a way to schedule the shutdown of Selenium nodes without breaking tests?
You could check the number of active sessions by requesting each node with the /sessions command:
http://127.0.0.1:4444/wd/hub/sessionsResponse :
{"state":"success","sessionId":null,"hCode":3217742,"value":[],"class":"org.openqa.selenium.remote.Response","status":0}
@Sh3mm
Sometime back I wrote up a blog post which basically talks about how to go about building a "Self Healing Grid" which is what you essentially are after.
You can read through my blog post on that from here.
We essentially used the same approach when we working on building the SeLion Grid. The SeLion Grid packs in a few more sophistications. Read more about it here
There's another flavor of essentially the same sort of functionalities that was built by GroupOn as part of their Grid Extras. You can take a look at it here