run cron jobs inside container in background when i am having a nodejs application as endpoint in foreground

Question

I am trying to deploy my application inside a kubernetes cluster by helm package. I have a nodejs application which queries cron jobs from database and should add these jobs to crontab file inside the same container.

So when I expose my container as a nodejs app in a port, I will make a add job request and these jobs are formatted to cron job type, and these entries needed to be added to crontab and execute these jobs in background.

Can this be achieved?

Answer 1

I think that you are looking for a job scheduler, you should try putting more than 1 process per container, maybe you can use another approach using an extra microservice that runs that jobs.

I recommend using Agenda

https://github.com/agenda/agenda

You can create an Agenda worker that has the code for the different jobs and the only thing that you need is to send a scheduled job or now execution, by this architecture you can have multiple agendas also as a sidecar container inside the same pod of your node application.

Answer 2

You can define a health check in the dockerfile. This is also possible in docker-compose and running docker container via cli.

HEALTHCHECK <options> CMD <your command with args> || exit 1

That will provoke that when you do docker ps you'll see if a container is running or stopped, and in case it's running, if it's healthy or not, i.e, if your command is being executed / has been executed properly.