Is there a way to inject environment variables to all of my docker-compose services, without explicitly declaring them in each service's configuration?

CodePudding user response：

1)using the env_file directive

you can use the env_file directive within your docker-compose.yml file

You can pass multiple environment variables from an external file through to a service’s containers with the ‘env_file’ option, just like with docker run --env-file=FILE ...:

you will have to declare the env file for each service that will use it and that is it.

example :

the docker-compose.yml file :

version: "3"
services:
  database:
    image: "ubuntu"
    tty: true
    env_file:
     - same-variables.env
  web:
    image: "ubuntu"
    tty: true
    env_file:
     - same-variables.env

the same-variables.env file

 IS_DOCKER_COMPOSE=yes

then if you do opening a terminal :

docker exec -it <docker_container> "echo $IS_DOCKER_COMPOSE"

result will be :

yes

2)using the .env file in project root

According to the doc: https://docs.docker.com/compose/environment-variables/#the-env-file

You can set default values for any environment variables referenced in the Compose file, or used to configure Compose, in an environment file named .env. The .env file path is as follows

Create an .env file as the root of your project as follow.

example :

your .env file :

TAG=v1.5

your docker-compose.yml file :

version: '3'
services:
  web:
    image: "webapp:$TAG"

organization of your project should be :

root_folder
|-.env
|-docker-compose.yaml

with the .env file with all your variable the env file will work for all of them at the same time