Environment variables on docker container are not override - docker

Question

I am kind of new to Docker and I have a Nextjs application running in a docker container. The app used some environment variables to communicate with the server. Here is where the problem appears. For some reason, when running the container and passing the env variables, they are created OK. Using docker inspect containerId I can see the correct value. However, when doing the real call to the server the value (server id) is the one that was set up on the build.
Building the image and passing the parameter. Let's say SERVER_API=127.1.2.3
docker build -t miTestImage --build-arg SERVER_API=$(SERVER_API) --rm --no-cache myNextjsApp/
By running the following command I can see the correct value was set up.
docker image inspect imageId
BUT, when running the image
docker run -itd -e SERVER_API=http://127.0.3.9:4000 --name myContianerApp -p 5000:5000 --rm imageId
and sending a request to the server, it is using the Old value (127.1.2.3) instead of the new one (http://127.0.3.9:4000)
And by doing:
docker inspect myContianerApp,
I can see the new value properly added but I don't understand why is not been picking up by the app.
I was reading this article where they have the following diagram. I'm doing the same steps but is not working for me. Do I missing something?
Any help/ clue is really appreciated.

Answer 1

Here's a working example:
FROM busybox
ARG SERVER="google.com"
ENV SERVER=${SERVER}
ENTRYPOINT "/bin/ash" "-c" "ping ${SERVER}"
Then:
docker build --tag=62270940 --file=./Dockerfile .
docker inspect 62270940 --format="{{.Config.Env}}"
[PATH=... SERVER=google.com]
docker run \
--interactive --tty \
62270940
PING google.com (172.217.14.238): 56 data bytes
64 bytes from 172.217.14.238: seq=0 ttl=52 time=13.850 ms
64 bytes from 172.217.14.238: seq=1 ttl=52 time=11.494 ms
docker run \
--interactive --tty \
--env=SERVER="stackoverflow.com" \
62270940
PING stackoverflow.com (151.101.1.69): 56 data bytes
64 bytes from 151.101.1.69: seq=0 ttl=55 time=13.763 ms
64 bytes from 151.101.1.69: seq=1 ttl=55 time=13.800 ms
64 bytes from 151.101.1.69: seq=2 ttl=55 time=25.678 ms