Docker container can't reach another container using container name - docker

Question

I have 2 Docker containers running in the same network and I want 1 of them to call another via spring Webclient.
I'm sure they all are in the same network -> docker network inspect <network_ID> proves this.
AFAIK I can ping one container from another to check if they can talk to each other by docker exec -ti attachment-loader-prim ping attachment-loader-sec
If I run this - I see responses from attachment-loader-sec like 64 bytes from 172.21.0.5: seq=0 ttl=64 time=0.220 ms, which means they can communicate.
When I send Postman request to attachment-loader-prim by its exposed port localhost:8085, I expect that after some business logic it calls for attachment-loader-sec via Webclient, but on that step I get a 500 error with such a message:
"finishConnect(..) failed: Connection refused:
attachment-loader-sec/172.21.0.5:80; nested exception is
io.netty.channel.AbstractChannel$AnnotatedConnectException:
finishConnect(..) failed: Connection refused:
attachment-loader-sec/172.21.0.5:80"
Both attachment-loader-prim and attachment-loader-sec can be accessed separately via postman and both send a response, no problem.
This is my docker-compose:
version: '3'
services:
attachment-loader-prim:
container_name: attachment-loader-prim
build:
context: ""
restart: always
image: attachment-loader:latest
environment:
SERVER_PORT: 8085
networks:
- loader_network
expose:
- 8085
ports:
- 8005:8005
- 8085:8085
attachment-loader-sec:
container_name: attachment-loader-sec
build:
context: ""
restart: always
image: attachment-loader:latest
environment:
SERVER_PORT: 8086
networks:
- loader_network
expose:
- 8086
ports:
- 8006:8005
- 8086:8086
networks:
loader_network:
driver: bridge
And this is a Webclient which makes a call:
class RemoteServiceCaller(private val fetcherWebClientBuilder: WebClient.Builder) {
suspend fun getAttachmentsFromRemote(id: String, params: List<Param>, username: String): Result? {
val client = fetcherWebClientBuilder.build()
val awaitExchange = client.post()
.uri("/{id}/attachment", id)
.contentType(MediaType.APPLICATION_JSON)
.bodyValue(params)
.header(usernameHeader, username)
.accept(MediaType.APPLICATION_OCTET_STREAM)
.awaitExchange {
if (it.statusCode().is2xxSuccessful) {
handleSucessCode(it)
} else it.createExceptionAndAwait().run {
LOG.error(this.responseBodyAsString, this)
throw ProcessingException(this)
}
}
return awaitExchange
}
private suspend fun handleSucessCode(response: ClientResponse) {
// some not important logic
}
}
P.S. BasicUri for Webclient defined as Config Bean like http://attachment-loader-sec/list
All my investigations brought me to such problems as:
Calling container using localhost instead of container name
Containers are not in the same network.
All that seems not relevant for me.
Any ideas will be really appreciated.

Answer 1

The problem was in calling a service without its port. The url became now http://attachment-loader-sec:8086/list and it is correct now. In my case I get 404, which means that my url path is not quite correct, but that is outside of current question