Run Scheduled Cron method in Spring from single pod if multiple pods exist on Kubernetes

Question

I am moving from single pod(docker image) to multiple pods for my Spring Application on Kubernetes for load handling. But I am facing an issue because I have a cron scheduler method in my application which runs daily at a particular time. If I deploy multiple pods, they all run simultaneously and as a result multiple entries get saved into my DB, but I want only a single pod to execute that function.

I have thought of generating java uuid and saving it in the DB as the function starts execution on each pod. Then in the same function, putting a sleep timer of, let's say, 5 seconds and comparing the uuid from the DB in each pod. The pod which updated the value in the database latest will match that value and will execute the method ahead.

Is this a good approach? If not, please give suggestions that can be done to solve this issue.

user_5657590 · Answer

You can use a quartz scheduler with JDBC store. This will take care of your requirement automatically.

In short: "Load-balancing occurs automatically, with each node of the cluster firing jobs as quickly as it can. When a trigger’s firing time occurs, the first node to acquire it (by placing a lock on it) is the node that will fire it."

Please refer to the official link for details- http://www.quartz-scheduler.org/documentation/quartz-2.3.0/configuration/ConfigJDBCJobStoreClustering.html

user_4476357 · Answer

Also, you can move the workload to an isolated process, this will be helpful and cleaner, check this out https://kubernetes.io/docs/concepts/workloads/controllers/cron-jobs/ this will give you an idea.

user_5778456 · Answer

the better approach is to configure your application to have multiple Spring Profiles and use cron only on one profile. Follow this tutorial https://faun.pub/spring-scheduler-in-multi-node-environment-49814e031e7c

Run Scheduled Cron method in Spring from single pod if multiple pods exist on Kubernetes

3 Answers