RabbitMQ listener in docker/microservice

Question

I have deployed a few microservice in aws ecs(via CI/CD through jenkins) Each task has its own service and task definition. Apache is running on the foreground and the docker will be deployed from its service if the apache is crashed.

My Dev team is using RabbitMQ to communicate between microservice. few microservice needs to listen to the certain event in the RabbitMQ server (Rabbit is installed on a separate news ec2 instance)

For listening to the rabbit MQ server should we run the listener as a daemon? Dev team have asked to run the following code at the time of docker deployment so that it will listen to the rabbit mq server.

php /app/public/yii queue/listen

and set a cron job so that the listener will start when it is crashed. For my best knowledge the docker container can run only one process in the foreground, Currently, Apache is running in the foreground. If I try to run the daemon (both the cron and the rabbit mq listener) in the background, The docker container won't restart when any of these daemon is crashed.

Is there any safer approach for this scenario? what is the best practice for running rabbit mq listener in docker container?

F.Madsen F.Madsen · Accepted Answer · 2019-03-14T09:35:13

If your problem is to run more processes in a container, a more general concept is to create a script eg. start_service.sh in you container and execute that in the CMD directives of your docker file. like this:

#!/bin/bash  
process1 ... &  
process2 ... &  
daemon-process1   

sleep infinite

The & will make the script continue after starting a process in the background even if it is not aimed to run as a daemon. The sleep infinite in the end will prevent the script from exiting, which would exit the container.

If you run several processes within your container, consider using an "init" process like dumb-init in the container. Read more here https://github.com/Yelp/dumb-init/blob/master/README.md

RabbitMQ listener in docker/microservice

1 Answers