Is the eureka service located in the same project as the service that's trying to access it?

Not.

I see what the problem is, I'll make the corrections and I'll try again.

Yes you can, click the + New button in the top right of an already existing project.

The private networks are isolated to each projects environments, it wouldn't be very private if any service from any project could access every service in any project.

I see what the problem is, I'll make the corrections and I'll try again.

For what it's worth, this forum is realtime, we can see each others edits and new messages in real time.

I adjusted the project, now the microservices are all within it, but an error was generated which I cannot understand because in the local environment the Service Registration and Discovery works well.

[2024-04-23 19:43:047] [ main ] [ INFO ] [com.netflix.discovery.DiscoveryClient:1041] Getting all instance registry info from the eureka server

[2024-04-23 19:43:048] [ main ] [ INFO ] [com.netflix.discovery.shared.transport.decorator.RedirectingEurekaHttpClient:84] Request execution error. endpoint=DefaultEndpoint{ serviceUrl='http://avineserver_eureka.railway.internal:8091/eureka/}, exception=Could not extract response: no suitable HttpMessageConverter found for response type [class org.springframework.cloud.netflix.eureka.http .EurekaApplications] and content type [text/html;charset=utf-8] stacktrace=org.springframework.web.client.UnknownContentTypeException: Could not extract response: no suitable HttpMessageConverter found for response type [class org.springframework.cloud.netflix .eureka.http.EurekaApplications] and content type [text/html;charset=utf-8]

at org.springframework.web.client.HttpMessageConverterExtractor.extractData(HttpMessageConverterExtractor.java:124)

Are you sure it's running on port 8091?

If I am sure the service is running on port 8081.

But I have some doubts, to give you context, the repository only has the eureka server microservice and that has an environment variable ${PORT} by which I can indicate the port on which the microservice will be executed. Now, I understand that railway builds a Docker image to run the “.jar” executable. What I am not clear about is why the port listens to the Docker image, if I can configure the port and where to see the docker mapping ports.

You just said 8081 but your error logs say 8091, was that a typo?

why the port listens to the Docker image

Sorry, but this sentence does not make technical sense.

Sorry, I correct… If I am sure the service is running on port 8091.

Java executables do not run within docker image?

They do, but your sentence does not make technical sense, at least in English.

Are you sure your eureka app is listening on ipv6? - https://docs.railway.app/guides/private-networking#listen-on-ipv6

Yeah that's right. Update the application.yml

server:
port: ${PORT:8091}
address: "::"

Docker Port Mapping [HOSTPORT]:[CONTAINERPORT]

I'm sure the HOST_PORT is 8091, but I don't know the container's listening port.

Do you know how I can see it or configure it?

The port your app listens on is the port you tell it to listen on.

That is, it is the same, it automatically takes the same one from the host.