We have built an app with flutter web and want to deploy it on different servers ( staging and prod ) with docker swarm as a part of a backend. The same image should be executable in both environments as we have to change the URLs we use. I'm looking for a possibility to set an environment variable in my docker-compose file which then can be read within the flutter app at runtime. By googling I only found solutions with static files or Gradle. But we don't use both.