Gateway for micro services without ports - spring-boot

Question

I need an API Gateway who'll be the "hub" for all my applications, but none of them will have ports cause they'll never be accessed directly and I can't chose a port since I don't know if the server will have that port free. If it is possible, I didn't found a way of doing it. Is there a tutorial or some document with example of that?
I don't know if it's a bug or if I didn't understand how to do it but I didn't found much info about that googling around.
I have an old application, made in Spring 1.5.2 who's using Zuul dependencies who can make requests to micro services without ports, I think he uses the Eureka's instance ID, is this possible with Spring Cloud Gateway?
My API Gateway application.properties
server.port = 8888
spring.application.name = api-gateway
ribbon.ServerListRefreshInterval = 1
ribbon.eureka.enabled = true
ribbon.eureka.ReadTimeout = 60000
ribbon.eureka.ConnectTimeout = 300000
## EUREKA-SERVICE
eureka.client.serviceUrl.defaultZone = ${EUREKA_URI:http://localhost:8761/eureka}
eureka.instance.instance.preferIpAddress = true
eureka.instance.instance.instance-id = ${spring.application.name}:${server.port}:${random.int}
#eureka.hystrix.command.default.execution.isolation.thread.timeoutInMilliseconds = 60000
hystrix.command.default.execution.timeout.enabled=false
spring.cloud.gateway.enabled = true
spring.cloud.gateway.x-forwarded.port-enabled = false
## ROUTE 0 -> PERSON-SERVICE
spring.cloud.gateway.routes.0.id = person
spring.cloud.gateway.routes.0.instance = person-service
spring.cloud.gateway.routes.0.uri = http://localhost
spring.cloud.gateway.routes.0.serviceUrl = http://localhost
spring.cloud.gateway.routes.0.predicates = Path=/person/api/**
spring.cloud.gateway.routes.0.ribbon.ReadTimeout = 150000
logging.level.org.springframework.cloud.gateway = DEBUG
logging.level.reactor.netty.http.client = DEBUG
My Person Service application.properties
## SERVIDOR
server.port=0
server.address=localhost
server.servlet.contextPath=/person/api
spring.application.name = person-service
## EUREKA
eureka.client.healthcheck.enabled=true
eureka.instance.preferIpAddress=1
eureka.instance.instance-id=${spring.application.name}:${server.port}:${random.int}
eureka.client.serviceUrl.defaultZone=${EUREKA_URI:http://localhost:8761/eureka}
The error log:
2021-01-28 10:00:25.402 DEBUG 5340 --- [ctor-http-nio-3] o.s.c.g.h.RoutePredicateHandlerMapping : Route matched: person
2021-01-28 10:00:25.403 DEBUG 5340 --- [ctor-http-nio-3] o.s.c.g.h.RoutePredicateHandlerMapping : Mapping [Exchange: GET http://localhost:8888/person/api/users] to Route{id='person', uri=http://localhost:80, order=0, predicate=Paths: [/person/api/**], match trailing slash: true, gatewayFilters=[], metadata={}}
2021-01-28 10:00:25.403 DEBUG 5340 --- [ctor-http-nio-3] o.s.c.g.h.RoutePredicateHandlerMapping : [5074d3a6-1] Mapped to org.springframework.cloud.gateway.handler.FilteringWebHandler#31dd80d9
2021-01-28 10:00:25.403 DEBUG 5340 --- [ctor-http-nio-3] o.s.c.g.handler.FilteringWebHandler : Sorted gatewayFilterFactories: [[GatewayFilterAdapter{delegate=org.springframework.cloud.gateway.filter.RemoveCachedBodyFilter#aa4d8cc}, order = -2147483648], [GatewayFilterAdapter{delegate=org.springframework.cloud.gateway.filter.AdaptCachedBodyGlobalFilter#242a209e}, order = -2147482648], [GatewayFilterAdapter{delegate=org.springframework.cloud.gateway.filter.NettyWriteResponseFilter#66213a0d}, order = -1], [GatewayFilterAdapter{delegate=org.springframework.cloud.gateway.filter.ForwardPathFilter#70c0a3d5}, order = 0], [GatewayFilterAdapter{delegate=org.springframework.cloud.gateway.filter.RouteToRequestUrlFilter#3cb8c8ce}, order = 10000], [GatewayFilterAdapter{delegate=org.springframework.cloud.gateway.filter.ReactiveLoadBalancerClientFilter#1835d3ed}, order = 10150], [GatewayFilterAdapter{delegate=org.springframework.cloud.gateway.filter.WebsocketRoutingFilter#5c8e67b9}, order = 2147483646], [GatewayFilterAdapter{delegate=org.springframework.cloud.gateway.filter.NettyRoutingFilter#474c9131}, order = 2147483647], [GatewayFilterAdapter{delegate=org.springframework.cloud.gateway.filter.ForwardRoutingFilter#1fde0371}, order = 2147483647]]
2021-01-28 10:00:27.574 ERROR 5340 --- [ctor-http-nio-5] a.w.r.e.AbstractErrorWebExceptionHandler : [5074d3a6-1] 500 Server Error for HTTP GET "/person/api/users"
io.netty.channel.AbstractChannel$AnnotatedConnectException: Connection refused: no further information: localhost/127.0.0.1:80
Suppressed: reactor.core.publisher.FluxOnAssembly$OnAssemblyException:
Error has been observed at the following site(s):
|_ checkpoint ⇢ org.springframework.cloud.gateway.filter.WeightCalculatorWebFilter [DefaultWebFilterChain]
|_ checkpoint ⇢ HTTP GET "/person/api/users" [ExceptionHandlingWebHandler]
Stack trace:
Caused by: java.net.ConnectException: Connection refused: no further information
at sun.nio.ch.SocketChannelImpl.checkConnect(Native Method) ~[na:1.8.0_271]
at sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:715) ~[na:1.8.0_271]
at io.netty.channel.socket.nio.NioSocketChannel.doFinishConnect(NioSocketChannel.java:330) ~[netty-transport-4.1.58.Final.jar:4.1.58.Final]
at io.netty.channel.nio.AbstractNioChannel$AbstractNioUnsafe.finishConnect(AbstractNioChannel.java:334) ~[netty-transport-4.1.58.Final.jar:4.1.58.Final]
at io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:707) ~[netty-transport-4.1.58.Final.jar:4.1.58.Final]
at io.netty.channel.nio.NioEventLoop.processSelectedKeysOptimized(NioEventLoop.java:655) ~[netty-transport-4.1.58.Final.jar:4.1.58.Final]
at io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:581) ~[netty-transport-4.1.58.Final.jar:4.1.58.Final]
at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:493) ~[netty-transport-4.1.58.Final.jar:4.1.58.Final]
at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:989) ~[netty-common-4.1.58.Final.jar:4.1.58.Final]
at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74) ~[netty-common-4.1.58.Final.jar:4.1.58.Final]
at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30) ~[netty-common-4.1.58.Final.jar:4.1.58.Final]
at java.lang.Thread.run(Thread.java:748) ~[na:1.8.0_271]
P.S: Sorry if my English is bad, it's still a WIP!

Answer 1

Okay, now it works somehow.
First, my "person" service wasn't at the same version, it was running Spring 2.3.1 and not Spring 2.4.2
Also, looks like when you have a "RestTemplate" config class annotated with "#LoadBalanced", Spring Boot treat your application as another layer of the Load Balancer and you can't access it just by puttin spring.cloud.gateway.routes.0.uri = lb://PERSON-SERVICE on the properties. Removing the "#LoadBalanced" from my Config class did the trick.
So, what you'll need to run this:
1- An API running as your Eureka Server
2- API Gateway with those properties
spring.cloud.gateway.routes.0.id = pessoa
spring.cloud.gateway.routes.0.uri = lb://PESSOA-SERVICE
spring.cloud.gateway.routes.0.predicates = Path=/pessoa/api/**
3- A micro service running with this name, like the properties below
server.port=0
server.servlet.contextPath=/person/api
spring.application.name = person-service
4- The class that have "#SpringBootApplication" need to be annotated with #EnableDiscoveryClient. If you're using JUST "#EnableEurekaClient" it won't work!
And that's enough to use a micro service without port.
Remember to run a mvn clean just to be sure!