I want to set an environment variable in my Dockerfile.
I've got a .env file that looks like this:
FOO=bar.
Inside my Dockerfile, I've got a command that parses the contents of that file and assigns it to FOO.
RUN 'export FOO=$(echo "$(cut -d'=' -f2 <<< $(grep FOO .env))")'
The problem I'm running into is that the script above doesn't return what I need it to. In fact, it doesn't return anything.
When I run docker-compose up --build, it fails with this error.
The command '/bin/sh -c 'export FOO=$(echo "$(cut -d'=' -f2 <<< $(grep FOO .env))")'' returned a non-zero code: 127
I know that the command /bin/sh -c 'echo "$(cut -d'=' -f2 <<< $(grep FOO .env))"' will generate the correct output, but I can't figure out how to assign that output to an environment variable.
Any suggestions on what I'm doing wrong?
If you want to set a number of environment variables into your docker image (to be used within the containers) you can simply use env_file configuration option in your docker-compose.yml file. With that option, all the entries in the .env file will be set as the environment variables in image and hence into containers.
If your requirement is to use some variables only within your Dockerfile then you specify them as below
ARG FOO
ARG FOO1
ARG FOO2
etc...
And you have to specify these arguments under the build key in your docker-compose.yml
build:
context: .
args:
FOO: BAR
FOO1: BAR1
FOO2: BAR2
If you are looking into passing some values into your docker-compose file from the .env then you can simply put your .env file same location as the docker-compose.yml file and you can set the configuration values as below;
ports:
- "${HOST_PORT}:80"
So, as an example you can set the host port for the service by setting it in your .env file