How to close client HTTP/2 connections?

[filex]

> Why do you want to do this?

In a cluster of many nginx servers we had one faulty node that was
delivering only errors. In that special case a default vhost replied an
"domain not configured" error, because the underlying configuration was
inaccessible. The health check was not firing, because such errors are
normal (bad bots try to access removed domains or simply make up host
headers).

A client that was round-robin balanced to that faulty nginx instance was
delivered the error page, but the connection was still active. Every
subsequent request to our domain had hit the same bad instance. The google
bot uses each connection for 100 requests. They all ran into the error. Same
for browsers: When you hit reload, you will run into the same problem until
the connection times out.

If the connection was closed immediately there would be a good chance to be
load-balanced to another instance.

In http/1 "Connection: close" does the job. but most of our traffic is h2.

Posted at Nginx Forum: https://forum.nginx.org/read.php?2,282096,282101#msg-282101