Run multiple Arconia services locally

[piotrooo]

Maybe it’s not really a question, but rather a topic for further discussion.

How do you handle situations where you need to run two services locally — for example, a user-service and a customer-service?

Each of them has its own database and uses AMQP. How do they connect to the same database? Or how do you avoid port conflicts?

Any thoughts on how to develop two services manually?

[ThomasVitale]

Arconia offers the possibility to share Dev Services across multiple applications, based on Testcontainers's own feature called "reusable containers".

In fact, some of the Dev Services like Artemis, RabbitMQ, Kafka, Ollama, and Grafana LGTM are shared by default when running in dev mode. Others are not. But you can control for each Dev Services whether it's shared and when (dev-mode only, or also in test mode).

You can read more about it here: https://docs.arconia.io/arconia/latest/dev-services/#_sharing_dev_services

Does that feature help with your use case?

When Dev Services are not shared, there is no port conflict as Testcontainers will always allocate a port dynamically. For example, if you have two applications running with the PostgreSQL Dev Service, each of them will have its own Dev Service instance on different port numbers.

[ThomasVitale]

I've been thinking about how to improve the sharing feature, for example by removing the requirement for setting the Testcontainers property explicitly on your machine. So, any feedback about this feature would be really appreciated to improve and evolve it. Thanks!

[piotrooo]

Ok, that sounds great — and I can confirm RabbitMQ works like a charm ❤️

By the way, how should I handle Tomcat port clashes (i.e., server.port and the management port)?

Right now, to run it correctly, I have to change the port manually. This causes connectivity issues when service A calls service B and the port has been changed.

[ThomasVitale]

I'm glad to hear the RabbitMQ Dev Service is working well for you!

About the server.port for Spring Boot itself, that is 8080 by default. Unlike Quarkus, Spring boot doesn't provide any facility to dynamically change the server port in case 8080 is busy already. That means it's up to you as the developer to change the port explicitly to something else when running in dev mode.

But it could be something Arconia might provide. I'll raise a feature request for it. Thanks for the input!

[ThomasVitale]

Here it is: #127

[piotrooo]

I have another interesting case (I guess 🤔).

Let's imagine you have two services: user-service and customer-service.

1️⃣st case

We’re running user-service locally. Its configuration points to customer-service deployed in the cloud (e.g., on Azure or AWS). It uses the URL https://customer-service.cloud.com.

2️⃣nd case (more interesting)

We’re running both user-service and customer-service locally. These services are configured to communicate with their local versions. So user-service uses the local URL of customer-service, e.g. http://localhost.
Maybe running a small and lightweight service discovery component would be a good trick?

WDYT?

[ThomasVitale]

For the first case, I would suggest configuring the URL via application.yml. It might be part of a dedicated profile, so that you can switch between a local instance of customer-service and a cloud one.

For the second case, if you want some service discovery mechanism, you could consider using Spring Cloud Eureka. Another option is to run each application on a different port and configure each of them to call other services via http://localhost:<port>. There are other options, but it all depends on the specific requirements and constraints of the environment.

[piotrooo]

For the second case, if you want some service discovery mechanism, you could consider using Spring Cloud Eureka.

And what if this discovery mechanism is provided by Arconia? How do you feel about that?