CLI: Pass command to docker-compose up - docker

Question

I have a docker-compose.yml (simplified example):
version: "3.8"
services:
server:
image: node:lts-slim
container_name: example-container
hostname: example-server
ports:
- 4000:4000
working_dir: /server
volumes:
- ./someLocalDirectory:/server
command: node --watch index.js
I create/start the container with docker-compose up -d server
Problem:
I'd prefer to not have command: node --watch index.js hardcoded inside the yml file.
Question:
Is it possible to pass command: node --watch index.js as an argument to docker-compose up -d server on the command line?
Thanks in advance :)
Solution:
You can prepend key-value-pairs on the command-line and treat them like regular variables inside docker-compose:
key="node --watch index.js" docker-compose up -d server
version: "3.8"
services:
server:
# ... see example above
command: ${key}
(see https://stackoverflow.com/a/50991623/1054981)

Answer 1

You have three options:
run:
You can use docker-compose run to run commands against a service.
For example:
docker-compose run server node --watch index.js
Note: container stops when command exits.
See also: docs
exec:
You can use docker-compose exec to run commands in a running container.
To start and keep your server running:
services:
server:
[..]
command: tail -f /dev/null
Start service:
docker-compose up -d server
Run commands:
docker-compose exec server node --watch index.js
See also: docs
using an environment variable:
You can pass an env var to your docker-compose file that contains the command you want to run.
Pass an environment variable to server:
services:
server:
[..]
command: $COMMAND
Run service:
COMMAND="node --watch index.js" docker-compose up -d server
See also: docs