How to deploy maven multi-module spring boot to docker container

Question

I'm setting up a multi-module maven project and trying to deploy it to docker a typical 3 layer project whit a separate container for a MYSQL DB.

I've been doing so research on the web and I came across the docker-compose a concept if I understand correctly with a config YAML file you can deploy each jar file into a different container and make them work together, ¿is this the only approach in my case?

Could I build one only jar file from the 3 modules and deploy it to the container? In my case i don't need to treat each project as a separate micro-service. On the other hand, I need docker compose because besides my spring boot project you need to run a container with a MYSQL DB and connect it to the spring-boot.

I'm not sure how to approach this scenario, thanks for any advice in advance.

Answer 1

Don't confuse having n-tiers in your application with a micro-service architecture.

Micro-services are separate units of deployment and communicate among themselves over some sort of protocol (http, a message bus, something). Calling a function in process (from one jar to another) is not that, and so your individual maven modules aren't candidates for being put in containers and orchestrated by docker-compose.

If your web app communicated with the Domain Layer via, say, a restful api, then you could use docker compose to spin up two separate containers.

But if, as is likely, your "api" is handled by controllers in the web app making in-process calls to your domain layer, you only have a single container to create and deploy.

There might still be good reasons to containerize your monolithic application. Perhaps it has complex OS dependencies and/or you want to deploy it to a PAAS like AWS Fargate or gCloud.

You might still want to use docker-compose as well, to deploy mysql in a container along side your web app.