Patch to be able to disable Keep-Alive on nginx via a nginx variable.
Nginx does not let you override the Connection: header (if you do it gets duplicated), so when you are running keep-alive and have a lot of long-running clients it can take quiet a bit to drain a host without stopping nginx on the host.
One possible way to do it is by writing some tools that modify the keepalive_timeout and reload nginx on certain conditions but the other way is to have a patch that tells nginx when it should send Connection: keep-alive.
This patch does "that" (patches nginx). It is very simple the way it is done, because you want to disable keep-alive more on runtime rather than with a setting then we add a new nginx variable: $disable_keep_alive_now.
Nginx will check the value of $disable_keep_alive_now every time it needs to send the Connection: header to the client, if the value is "yes" then it will send a Connection: close otherwise it follows its normal path which can be sending a keep-alive or a close (if the keep-alive connection timed out).
An example:
location / {
if (!-f "healthcheck/path") {
set $disable_keep_alive_now "yes";
}
}
Enjoy!