Docker Compose for Node.js

1. Introduction

Docker Compose is a tool for defining and running multi-container Docker applications. In this lesson, we will explore how to use Docker Compose with a Node.js application, allowing for easy management of application dependencies and services.

2. Key Concepts

**Container:** A lightweight, standalone, executable package of software that includes everything needed to run a piece of software.
**Dockerfile:** A text document that contains all the commands to assemble an image.
**Docker Compose File:** A YAML file defining services, networks, and volumes for a Docker application.

3. Installation

To use Docker Compose, you need to have Docker installed on your machine. Follow these steps:

Install Docker from the official website.
Verify the installation by running docker --version and docker-compose --version in your terminal.

4. Creating a Dockerfile

Create a file named Dockerfile in your Node.js project directory:

FROM node:14

# Create app directory
WORKDIR /usr/src/app

# Install app dependencies
COPY package*.json ./
RUN npm install

# Bundle app source
COPY . .

EXPOSE 8080
CMD [ "node", "app.js" ]

5. Creating a Docker Compose File

Create a file named docker-compose.yml in your project directory:

version: '3'
services:
  web:
    build: .
    ports:
      - "8080:8080"
    volumes:
      - .:/usr/src/app
    environment:
      - NODE_ENV=production

6. Running the Application

To start your application using Docker Compose, run:

docker-compose up

To run it in detached mode, use:

docker-compose up -d

7. Best Practices

Consider the following best practices:

Keep your images small by using a minimal base image.
Leverage Docker caching by ordering commands in your Dockerfile effectively.
Use environment variables for configuration rather than hardcoding values.
Regularly update your base images to include the latest security patches.

8. FAQ

What is Docker Compose?

Docker Compose is a tool for defining and running multi-container Docker applications using a simple YAML file.

How do I stop my application?

You can stop your application by running docker-compose down in your terminal.

Can I run multiple services with Docker Compose?

Yes, you can define multiple services in the docker-compose.yml file and manage them together.