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

There are generaly two options, because docker doesn't support this feature now:

1. Create your own script, which will act like runner for your command. For example:

   #!/bin/bash
   export VAR1=VAL1
   export VAR2=VAL2
   your_cmd
   

2. Run your command following way:

   docker exec -i CONTAINER_ID /bin/bash -c "export VAR1=VAL1 && export VAR2=VAL2 && your_cmd"
   

Answer 2

Use export VAR=Value

Then type printenv in terminal to validate it is set correctly.

Answer 3

If you are running the container as a service using docker swarm, you can do:

docker service update --env-add <you environment variable> <service_name>

Also remove using --env-rm

To make sure it's addedd as you wanted, just run: docker exec -it <container id> env

Answer 4

here is how to update a docker container config permanently

1. stop container: docker stop <container name>
2. edit container config: docker run -it -v /var/lib/docker:/var/lib/docker alpine vi $(docker inspect --format='/var/lib/docker/containers/{{.Id}}/config.v2.json' <container name>)
3. restart docker

Answer 5

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.