Using Docker to virtualize your development environment

app.js

console.log("app started");
setInterval(() => {
    console.log("hello there");
}, 2000);

docker-compose.yml

# To build these services:
#   docker-compose build
#
# To run these services container: 
#   docker-compose up
#
# To shut down these services:
#   docker-compose down

version: '2'

services:
    app:
        container_name: app
        build: .
        volumes:
            - .:/app
        command: pm2-docker --watch app.js

docker-p1-virtual-environment.md

What is a virtual environment

Docker is used to virtualize a development environment so that everyone has the same tools, software, and running source code.

Terms

Host: Your computer (macOS).

Guest: The virtual machine (and any containers inside of it).

Reasons to use it

1. Have the environment start up identically everytime.

   $ docker-compose build
   ...
   $ docker-compose up
   

2. Be able to SSH into guest operating system so I can interact with or debug things.

   docker exec -it app bash
   

3. Have the files on my host filesystem so my IDE can work with them.

4. When I make file changes, automatically restart the application so that development is seamless.

   • I don't have to deploy code locally.

5. Have the same OS and configuration on development and remote environments (more on this later in docker-p2-deployment).

   • No more "it works on my computer" scenarios.

How

See the included docker-compose.yml, Dockerfile, and app.js.

Dockerfile

# To build this image: 
#   docker build -t app .
#
# To run this image as a container: 
#   docker run --name app --rm -it app

FROM node:6

RUN npm install --global pm2

WORKDIR /app

COPY . /app

CMD node app.js