I am trying to dockerize a simple phoenix api rest service I have tried with the next two docker files:

FROM elixir:latest

RUN apt-get update && \
apt-get -y install sudo

ADD . /app

RUN mix local.hex --force \
&& mix local.rebar --force
RUN mix archive.install hex phx_new 1.4.0-dev.0

RUN curl -sL https://deb.nodesource.com/setup_12.x | bash -
RUN apt-get install -y nodejs

WORKDIR /app

RUN cd assets && npm install

RUN cd ../

RUN mix deps.get

RUN mix compile

EXPOSE 4000

CMD ["mix", "clean"]
CMD ["mix", "ecto.setup"]
CMD ["mix", "phx.server"]

And a more simple one:

FROM elixir:alpine

RUN apk update

ADD . .

RUN mix local.hex --force && mix local.rebar --force
RUN mix archive.install hex phx_new --force
RUN apk update && apk add inotify-tools
RUN mix deps.get
RUN mix compile

CMD ["mix", "clean"]
CMD ["mix", "ecto.setup"]
CMD ["mix", "phx.server"]

With both I am able to create the docker image and also to run the docker container but when I try to hit any endpoint (from postman) I get the next:

postmanerror1509×344 13.2 KB

postmanerror2473×255 6.74 KB

Any ideas of why am I getting this?

I have already research about the socket hang up error in postman and may be related to the ports already in use but the problem here is that I am not using any of the ports where I expose or map with my docker container when running docker run -p XXXX:XXXX <image-name>.

Please can you help me with this?