How do I pass environment variables to Docker containers?
Posted By: Anonymous
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?
# Dockerfile
ENV DATABASE_URL amazon:rds/connection?string
Solution
You can pass environment variables to your containers with the -e
flag.
An example from a startup script:
sudo docker run -d -t -i -e REDIS_NAMESPACE='staging'
-e POSTGRES_ENV_POSTGRES_PASSWORD='foo'
-e POSTGRES_ENV_POSTGRES_USER='bar'
-e POSTGRES_ENV_DB_NAME='mysite_staging'
-e POSTGRES_PORT_5432_TCP_ADDR='docker-db-1.hidden.us-east-1.rds.amazonaws.com'
-e SITE_URL='staging.mysite.com'
-p 80:80
--link redis:redis
--name container_name dockerhub_id/image_name
Or, if you don’t want to have the value on the command-line where it will be displayed by ps
, etc., -e
can pull in the value from the current environment if you just give it without the =
:
sudo PASSWORD='foo' docker run [...] -e PASSWORD [...]
If you have many environment variables and especially if they’re meant to be secret, you can use an env-file:
$ docker run --env-file ./env.list ubuntu bash
The –env-file flag takes a filename as an argument and expects each line to be in the VAR=VAL format, mimicking the argument passed to –env. Comment lines need only be prefixed with #
Answered By: Anonymous
Disclaimer: This content is shared under creative common license cc-by-sa 3.0. It is generated from StackExchange Website Network.