Docker：如何在不重启Docker容器的情况下永久更改env var值

Question

I have a docker container which is already started :

When i run : docker exec -it myContainer bash

and then echo $myEnvVar -> i get : myEnvVar= value1

i'm trying to change the value of this env var :

i ve tried to do : export myEnvVar=value2 inside the container

and from the host server : docker exec -it myContainer bash -c "export myEnvVar =value2"

or alson another way : docker exec -it -e myEnvVar =value2" myContainer bash

All those tentatives fails as it is setting this new value2 o nly in the current session

Therofore when i exit from the container and reconnect to it ,

i found that my var is still equal to the first value myEnvVar= value1

Suggestions to handle it without restarting the container ?

Answer 1

not a docker guy but found some useful thread, may be it will help.

follow the thread: https://github.com/moby/moby/issues/8838

You can try one approach: just stop docker daemon and change container config in

/var/lib/docker/containers/[container-id]/config.json

You can find container-id by executing

docker inspect [container-name]

Answer 2

Environment variables are defined on a process when you create the process, and a running docker container is a wrapper around a running process. Therefore, it's not possible to achieve your request even if docker wanted to make it possible.

Your request also goes against the best practices to make your containers disposable and replaced to implement changes. By modifying an existing container, you are creating a fragile "pet", rather than a fault tolerant "cattle" environment.

The recommended solution to changing an environment variable for a container is to replace the container with a new container that has the desired environment variable defined. When you have lots of settings to run your containers, consider using a docker-compose.yml file and deploying your containers with docker-compose or docker stack deploy . This makes it easy to define the new settings in a config file and replaces the needed containers with a single "up" or "deploy" command.