<h1 style='font-size:26px;color:#6aa84f;'>docker: create a dockerimage from a dockerfile with a node.js app in it</h1>

Let's create a node.js dockerkerimage with a dockerfile and let us start a node.js app on this container

Prerequisits

We need some things installed on the local machine.

• node.js installed
• npm installed
• docker installed

Install node.js sampleapp

If you already have a node.js to pack you can leave this step

We want to use a simple express app with a hello world text, to demonstrate that the webapp is running on our container

Install an express and express-generator

$ npm install -g express express-generator

$ npm install

Create an express project

$ express sampleApp

This will generate our skeleton app in the current folder.

Create our DockerFile

With a DockerFile we are able to describe what we want to install on the container in a easy readable configfile. If you want to see the documentation, what commands the DockerFile can execute, here is the documentation

Now we want to to following things automated by the dockerfile. This can be managed by the following dockerfile

Save following content in a file "Dockerfile" in your project-skeletons root

FROM node:latest

MAINTAINER Peter Böthig

ENV NODE_ENV=production
ENV PORT=3000

COPY . /var/www
WORKDIR /var/www

RUN npm install

EXPOSE $PORT

ENTRYPOINT ["npm", "start"]

To explain that

• Line 1 load a node baseimage
• Line 2 define a maintainer (your username in thinat case)
• Line 3 & 4 define enviromentvariables, to switch from dev to prod
• Line 5 copy our sourcecode to the container in "var/www"
• LINE 6 define a workingdirectory
• Line 7 run npm install
• Line 8 Expose the default webserverport (prod/live)
• Line 9 start the express webserver

Create our image from the Dockerfile

Now, that we have created our Dockerfile we can create our first image from it.

Open a terminal in the folder where your Dockerfile lives

docker build -f Dockerfile -t <yourdockerhub-username>/node-express

This will create your image

You can see you new image with

docker images

Create a new container from your image

Now, that we have created our image from the dockerfile we can create a new container and run our sample app

Open a terminal in the folder where your Dockerfile lives

docker run -d -p 8081:3000 <yourdockerhub-username>/node-express

Now you can reach your app under http://localhost:8081