Learn the fundamentals of Docker by containerizing a Node.js app 172 words.
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Code Breakdown
Dockerfile
A Dockerfile is like DNA for building a Docker Image.
Dockerfile
FROM node:12
WORKDIR /app
COPY package*.json ./
RUN npm install
COPY . .
ENV PORT=8080
EXPOSE 8080
CMD [ "npm", "start" ]
Dockerignore
A Dockerignore file is required so we don’t add the node_modules folder to the image.
.dockerignore
node_modules
Node.js App
This is the code we went to run as the container’s process.
src/index.js
const app = require('express')();
app.get('/', (req, res ) =>
res.json({ message: 'Docker is easy 🐳' })
);
const port = process.env.PORT || 8080;
app.listen(port, () => console.log(`app listening on http://localhost:${port}`) );
Commands
Build the Image
command line
docker build -t fireship/demoapp:1.0 .
Run the Container
This maps the local port 5000 to the docker port 8080. You should be able to view the app on your local system at https://localhost:5000. You can choose any port you want.
command line
docker run -p 5000:8080 <image-id>
Docker Compose
Docker Compose makes it easy to manage multiple containers and volumes.
docker-compose.yml
version: '3'
services:
web:
build: .
ports:
- "8080:8080"
db:
image: "mysql"
environment:
MYSQL_ROOT_PASSWORD: password
volumes:
- db-data:/foo
volumes:
db-data:
Run multiple Containers
command line
docker-compose up