Setting global environment variables in docker-compose - docker

Question

I am looking for a way to set global environment variables in my docker-compose.yml file so that I won't need to duplicate them. What is the best way to do it? As you can see some environment variables are repeated in multiple containers. I don't want to re-write them many times.
version: "3.4"
services:
test-db:
image: postgres-test:1.4.0
environment:
- POSTGRES_PASSWORD=password
- DB_NAME_1=dbname1
- DB_USER_1=dbuser1
- DB_PASS_1=dbpass1
- DB_NAME_2=dbname2
- DB_USER_2=dbuser2
- DB_PASS_2=dbpass2
volumes:
- test-db-data:/var/lib/postgresql/data
restart: on-failure
ports:
- 5432:5432
networks:
- test
test-key:
image: key-test:1.4.0
environment:
DB_VENDOR: POSTGRES
DB_ADDR: test-db
DB_DATABASE: dbname1
DB_USER: dbuser1
DB_PASSWORD: dbpass1
KEY_USER: admin
KEY_PASSWORD: admin
#KEY_LOGLEVEL: DEBUG
KEY_FRONTEND_URL: http://test-key:8080/auth
KEY_IMPORT: /test-key/test_realm.json
command:
- "-Djboss.as.management.blocking.timeout=3600"
ports:
- 8080:8080
volumes:
- $PWD/test_realm.json:/test-key/test_realm.json
networks:
- test
depends_on:
- test-db
test-bus:
image: bus-test:1.5.0
environment:
PYTEST_HOST: test-pytest
PYTEST_PORT: 8090
TEST_DB_PW: dbpass2
TEST_DB_USER: dbuser2
TEST_DB_NAME: dbname2
TEST_DB_HOST: test-db
TEST_KAF_HOST: test-kaf
TEST_KAF_PORT: 9092 # for a connection inside test-network
#TEST_SERVER_STATE: PRODUCTION
TEST_SERVER_STATE: DEVELOPMENT
ports:
- 5000:5000
networks:
- test
depends_on:
- test-db
- test-key

Answer 1

You can define your variables in an env-file named .env beside docker-compose.yml file.
.env
dbname1_key=dbname1
dbuser1_key=dbuser1
dbpass1_key=dbpass1
Then you can use the variable in docker-compose.yml file
docker-compose.yml
version: "3.4"
services:
test-db:
image: postgres-test:1.4.0
environment:
- POSTGRES_PASSWORD=password
- DB_NAME_1=${dbname1_key}
- DB_USER_1=${dbuser1_key}
- DB_PASS_1=${dbpass1_key}
- DB_NAME_2=dbname2
- DB_USER_2=dbuser2
- DB_PASS_2=dbpass2
volumes:
- test-db-data:/var/lib/postgresql/data
restart: on-failure
ports:
- 5432:5432
networks:
- test
...