With docker-compose v2 environment variables can be set by simply:
enviroment:
- MONGO_PATH=mongodb://db-mongo:27017
The full docker-compose.yml file being:
version: '2'
services:
web:
build: .
environment:
- MONGO_PATH=mongodb://db-mongo:27017
ports:
- "3000:3000"
volumes:
- .:/app
- /app/node_modules
depends_on:
- db-mongo
- db-redis
db-mongo:
image: mongo
restart: unless-stopped
command: --smallfiles
ports:
- "27017:27017"
volumes:
- ./data:/data/db
[...]
However, how can I escape environment variables that are not a plain string?
{"database": {"data": {"host": "mongo"}}}
I tried:
NODE_CONFIG=\{"database": \{"data"\: \{"host": "mongo"\}, "session": \{"host": "redis" \}\}\}
NODE_CONFIG="\{"database": \{"data"\: \{"host": "mongo"\}, "session": \{"host": "redis" \}\}\}"
NODE_CONFIG='{"database": {"data": {"host": "mongo"}, "session": {"host": "redis" }}}'
ERROR: yaml.parser.ParserError: while parsing a block mapping in "./docker-compose.yml", line 6, column 9 expected , but found '}' in "./docker-compose.yml", line 6, column 92
Environment variables (including their name), have to be fully wrapped inside single or double quotes: "" or ''
environment:
- 'NODE_CONFIG={"database": {"data": {"host": "mongo"}, "session": {"host": "redis" }}}'
And using double quotes:
environment:
- 'PORT=3000'
- "NODE_CONFIG={\"database\": {\"data\": {\"host\": \"mongo\"}, \"session\": {\"host\": \"redis\" }}}"
It is remarkable to note that using double quotes "", like bash, will allow placing variables inside the environment variable.
"MY_HOME_ENV_VARIABLE=${HOME}"