Environment variables in score-compose

This section describes how to define environment variables for score-compose.

  2 minute read  

When docker compose runs a service, it is possible to pass information from the host to the container through environment variables.

This hello world example provides an Overview section and two options to resolve your variable name:

Overview

The Score Specification uses a special environment property type that is specified in the resources section.

apiVersion: score.dev/v1b1

metadata:
  name: hello-world

containers:
  hello:
    image: busybox
    command: ["/bin/sh"]
    args: ["-c", "while true; do echo Hello $${FRIEND}!; sleep 5; done"]
    variables:
      FRIEND: ${resources.env.NAME}

resources:
  env:
    type: environment

Use the run command to generate a Docker Compose file from Score.

score-compose run -f ./score.yaml \
  -o ./compose.yaml

The compose.yaml file contains a single service definition and utilizes a host environment variable called NAME.

The following compose.yaml file is the output of previous.

services:
  hello-world:
    command:
      - -c
      - 'while true; do echo Hello $${FRIEND}!; sleep 5; done'
    entrypoint:
      - /bin/sh
    environment:
      FRIEND: ${NAME-World}
    image: busybox

Environment configuration file

It is recommended to declare your environment configuration in a .env file.

Use the --env-file flag with the score-compose CLI tool to additionally produce a .env file that can be used alongside the generated compose file.

score-compose run -f score.yaml \
  -o compose.yaml \
  --env-file hello.env

The --env-file flag will create a file that can be used with the Docker platform.

The following is the output of the previous command in the hello.env file.

NAME=World

Run the docker compose command with the --env-file flag, specify the path to your .env file.

docker compose -f compose.yaml --env-file hello.env up

The following is the output of the previous command.

[+] Running 1/0
 ⠿ Container score-compose-hello-world-1  Created   0.0s
Attaching to score-compose-hello-world-1
score-compose-hello-world-1  | Hello Hello!

Results you’ve successfully passed an environment variable through an .env file.

Environment configuration in your shell

To use environment configurations in your shell, assign a value to a variable using your shell’s built-in export command.

The following example sets the environment variable to Hello.

export NAME=Hello
docker compose -f ./compose.yaml up

The following is the output of the previous command.

[+] Running 1/0
⠿ Container score-compose-hello-world-1  Rec...       0.1s
Attaching to score-compose-hello-world-1
score-compose-hello-world-1  | Hello Hello!

Learn more

For more information, see the following links.