A script to be used as a preStop hook on kubernetes for resque workers

resque-prestop.sh

#!/bin/bash

# This script issues a SIGQUIT to the resque worker and waits for all jobs
# (forked processes) to be finished before exiting. To be used as a preStop hook
# for resque processes on Kubernetes.
# Kubernetes by default issues a SIGTERM when terminating a pod, but that causes
# resque to immediately kill child processes and then exit. A SIGQUIT tells resque
# to wait for child to finish before exiting.
# Set `terminationGracePeriodSeconds` to the number of seconds to wait before
# ignoring this preStop script and forcing the pod to terminate.
#
# References:
# * https://gist.github.com/Cryptophobia/447ecea7858d26141359b22161e70ee2
# * https://github.com/resque/resque/tree/v1.25.2#signals

set -x

kill -QUIT 1;
#if resque workers present, wait 10 seconds and check again
numWorkers=$(ps aux | grep -i '[p]rocessing' | wc -l);

echo "Running the preStop hook";

while true; do
    if [ "$numWorkers" -eq "0" ]; then
        #exit when all resque workers are terminated
        echo "Time to terminate this pod";
        break;
    else
        echo "Not ready to exit, workers are processing, more sleepy sleepy.";
        echo "$numWorkers -- number of workers processing.";
        sleep 5;
        kill -QUIT 1;
        numWorkers=$(ps aux | grep -i '[p]rocessing' | wc -l);
    fi
done;

echo "Exiting from the bash script";