docker-compose - how to escape environment variables

Question

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

Answer 1

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}"