How to set an environment variable in a running docker container

Question

If I have a docker container that I started a while back, what is the best way to set an environment variable in that running container? I set an environment variable initia

Answer 1

Docker doesn't offer this feature.

There is an issue: "How to set an enviroment variable on an existing container? #8838"

Also from "Allow docker start to take environment variables #7561":

Right now Docker can't change the configuration of the container once it's created, and generally this is OK because it's trivial to create a new container.