How do I pass environment variables to Docker containers?

Question

I\'m new to Docker, and it\'s unclear how to access an external database from a container. Is the best way to hard-code in the connection string?

# Dockerfil         


        

Answer 1

Use -e or --env value to set environment variables (default []).

An example from a startup script:

 docker run  -e myhost='localhost' -it busybox sh

If you want to use multiple environments from the command line then before every environment variable use the -e flag.

Example:

 sudo docker run -d -t -i -e NAMESPACE='staging' -e PASSWORD='foo' busybox sh

Note: Make sure put the container name after the environment variable, not before that.

If you need to set up many variables, use the --env-file flag

For example,

 $ docker run --env-file ./my_env ubuntu bash

For any other help, look into the Docker help:

 $ docker run --help

Official documentation: https://docs.docker.com/compose/environment-variables/