This assumes you have created a Sails app on docker using the docker run command.

Let's say you have installed an app named foo-app, and the files for the app reside at /usr/local/apps/foo-app on your Docker server. Move into the dirctory.

cd /usr/local/apps/foo-app

Before you can start a Sails app on Docker using Docker Compose, you will need to install Docker Compose.

Create a YAML file named docker-compose.yml. 

touch /usr/local/docker/sails/docker-compose.yml

Append the following to docker-compose.yml. Let's break this down.

AVOID TROUBLE

By default, in the container, the app will be located at /<app name>, such as /foo-app in this example. The volume option will need to point to /<app name>.

• The nodejs/sails:latest image is used
• The --volume option is used to define the directory on the Docker server (/usr/local/app) that will be mounted to a directory in the container (/foo-app).
• The --workdir option is used to define the directory on the Docker server (/foo-app) where the app will be created.

version: '3'
services:
  api:
    ports:
      - '8080:1337'
    volumes:
      - /user/local/apps:/foo-app
    working_dir: '/foo-app'
    command: /bin/bash -c "sails lift --silly &"