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

To:

1. set up many env. vars in one step,
2. prevent exposing them in 'sh' history, like with '-e' option (passing credentials/api tokens!),

you can use

--env-file key_value_file.txt

option:

docker run --env-file key_value_file.txt $INSTANCE_ID