A Node App Container

Here, a docker image will be built.
The image will run a nodeJs web server that can be pinged at a "root" url and return a string that reads "omg hey!!".

A Node App Container

Create a Directory to Hold Everything

# in a terminal
mkdir a-node-image
cd a-node-image
touch index.js

Create A Simple Node Server

// index.js
const http = require('http')
http.createServer((res,res) => {
  console.log('req recieved!')
  res.end('omg hey!!', 'utf-8')
})
.listen(3000)
console.log('server started!')

Handle The Image Details

Create A Dockerfile To Instruct Docker

# make a dockerfile inside the a-node-image directory
touch Dockerfile

Edit the dockerfile:

# pull the node stretch img
FROM node:18

# copy the http server file from the computer's filesystem "into" the docker image space
COPY index.js index.js

# run the index.js file using node
CMD ["node", "index.js"]

Build The Image

# at the root of the a-node-image dir
docker build -t node-box .

tagging the app image to a friendly name of node-box
. tells docker to look at the current directory for a file called Dockerfile
should see some output about the image build process!
why the hashes in the output?!
- there are valid containers throughout the build process, for each step, or each STAGE
- at each Stage of the build process, a new image gets built and saved to optimize any other image builds from the same stage steps

Run The Image As A Container

docker run node-box

trying to ACCESS this node app from a bworser won't work
the containerized node app is not available to the "world", to the host machine
cant hit ctl+c to quit the container
- docker gives a hack flag that allows ctrl+c to work...

docker run --init --rm node-box

the --init flag runs 'tini', so that when i want to quit the container by typing ctrl+c, tini does it for me!
the --rm flag removes the container on shutdown

Allow Network Traffic Between Host And Container

allow network traffic from host to container

expose port 3000 of the running container to the host machine, so that navigating to localhost:3000 hits the container and returns the expected result in the browser

docker run --publish 3000:3000 node-box

the --publish flag maps internal port to external port!

Tags:

Docker