Kubernetes Nginx: How to have zero-downtime deployments?
I hate answering my own questions, but after noodling a bit this is what i have so far.
I created a bash script that is semi-blocking, called killer:
#!/bin/bashsleep 3PID=$(cat /run/nginx.pid)nginx -s quitwhile [ -d /proc/$PID ]; do sleep 0.1doneI found that inside the nginx pod there is a file /run/nginx.pid which has the PID of the master process. If you call nginx -s quit and initiate a wait until the process disappears, you have essentially made the quit command "blocking".
Note that there is a sleep 3 before anything happens. This is due to a race condition where Kubernetes marks a pod as terminating, but takes a little time (< 1s) to remove this pod from the service that points traffic toward it.
I have mounted this script into my pod, and called it via the preStop directive. It mostly works, but during testing there are still occasional blips where i get a curl error that the connection was "reset by peer." But this is a step in the right direction.