docker-compose exec does not execute command even when container is running

Question

I have a docker-compose-custom.yml file like this:

version: '3.8'

services:
  myapp-back-preproduction:
    build:
      context: .
    container_name: myapp-back-preproduction
    image: 'myapp-back-preproduction:latest'
 ....

I want to execute a simple command within the container after this one started to run using docker-compose exec:

docker-compose -p myapp-back-preproduction -f docker-compose-custom.yml exec npm install

I expect npm install to be executed within the container.

But it displays nothing in the console, it simply returns.

docker exec instead works but it logically lacks all environment variables declared in my docker-compose-custom.yml file; I want to use docker-compose exec.

My docker-compose version is: 1.29.2

How to make it work?

Answer 1

You messed up with the syntax.

$ docker-compose exec -h
Execute a command in a running container

Usage: exec [options] [-e KEY=VAL...] [--] SERVICE COMMAND [ARGS...]

Your command should be like:

docker-compose -f docker-compose-custom.yml exec myapp-back-preproduction npm install

-p switch is for specifying a project name: identifier that used to construct container name like <project_name>_<service_name>_1

Answer 2

You can use docker exec -it <container> <command> to execute a command in a running container (see docs). Notably, this enables you to start an interactive shell session within the container, which is really handy for all sorts of things.

I do wonder why you would need to call npm, though. If this is necessary to run your application, it should be done in the Dockerfile. (Alternatively it could be done in a start-up script.)

Do note that your container will only stay up while it is actually running an application (that is, while the entry point call did not return), so starting up an inactive container and then manually running applications won't work. The container would simply be stopped immediately.

Answer 3

this is sample command

docker-compose exec nginx apk add nodejs

it that command i try to install nodejs, so the command you need to execute

docker-compose exec container_namme npm install xxx