Problem with Docker When Deploying Container in Railway. App

I have deployed a serverpod project (dart) through a docker (in a railway.app host). but although the container is built correctly, I can't access it from the domain provided by railway. The container should expose port 8080 but I can't get it to work and I'm out of ideas, can someone help me?? I leave you a copy of the dockerfile

FROM dart:stable AS build

`WORKDIR /app
COPY . .

RUN dart pub get
RUN dart compile exe bin/main.dart -o bin/main

FROM jenkins/jenkins:lts
USER root
RUN apt-get update && \
    apt-get -y install apt-transport-https \
         ca-certificates curl gnupg2 \
         software-properties-common && \
    curl -fsSL (. /etc/os-release; echo "$ID")/gpg > /tmp/dkey; apt-key add /tmp/dkey && \
    add-apt-repository \
      "deb [arch=amd64] (. /etc/os-release; echo "$ID") \
      $(lsb_release -cs) \
      stable" && \
    apt-get update && \
    apt-get -y install docker-ce
USER jenkins


ENV runmode=staging
ENV serverid=default
ENV logging=normal
ENV role=monolith

COPY --from=build /runtime/etc /etc
COPY --from=build /runtime/lib /lib
COPY --from=build /runtime/lib64 /lib64
COPY --from=build /runtime/usr /usr
COPY --from=build /app/bin/main /app/bin/main
COPY --from=build /app/config/ config/
COPY --from=build /app/generated/ generated/
COPY --from=build /app/web/ web/

EXPOSE 8080
EXPOSE 8081
EXPOSE 8082`

CMD app/bin/main --mode $runmode --server-id $serverid --logging $logging --role $role

I have tried different configurations. in my local environment when i build the image with " docker build -t <name:tag>

and then run it with docker run -p 8080:8080 <name:tag>

works fine, i can access the container via localhost:8080. but in railway I don't have the possibility to execute it that way