This is a very basic, 20 minute quick guide to running your first docker container running an application.


Verify your installation

  1. Start the docker service on your machine and check the docker version.

     docker -v
  2. Run your first hello world container

     docker run --name hello hello-world

Playing with your installation

  1. Ok, so your container can say hello, can you run some other commands inside it?

     docker run busybox uptime

Don’t try this at ‘host’

  1. So, if it’s an OS, can I log into it on the command line and actually do stuff? Sure!!

     docker run -it busybox sh

    Now try


    Surprise surprise!! You’re root!! But wait, if I’m root now, can’t I do anything? I mean ANYTHING !! Let’s try something crazy!!

    PS: Make sure you’re still inside the container, you DON’T want to do this on your machine.

     # ok, so commands work! Also..
     # I see bin.. evil laugh.. let me wreak havoc, and delete it!! I'm ROOT!!
     rm -rf bin
     # and now..
     # Honey I blew up the machine!! Did I break my host machine too?

    However, once outside of the container, try ls and uptime again (if you’re on a linux/ mac that is..), and they’re still working..

    Voila! Docker isolation in action!!

Serving a static webpage

  1. I have an html page, and I want to serve it using an nginx server..

     # Creating an simple webpage that says Hello!!
     echo <html><head></head><body>Hello!!</body></html> > index.html
     # Installing and enabling an httpd server in one single command
     docker run -dit --name my-web-server -p 8080:80 -v "$PWD":/usr/local/apache2/htdocs/ httpd:2.4
     # Launch your browser and check your machine's port 8080 (mac/ linux)
     open "http://localhost:8080"   # for mac
     explorer "http://localhost:8080"   # for windows
  2. Cleanup running containers

     docker ps 
     # Notice the status of the container named my-web-server. Stop it
     docker stop my-web-server
     # Remove the container
     docker container rm my-web-server

Dockerizing a node.js app

  1. Let’s now do something a little more real world!! Let’s get our hands on a very simple node app, create a docker container for it, push it to a repo, and learn how to pull and run it.

  2. Login to github and pull the following repository:

     git clone
     # consider running the application locally if you have node installed on your machine
     npm install
     node index.js
     # But the happy scenario, in case you don't have nodejs installed on your machine, docker to the rescue
  3. Explore the code.. as a shortcut, consider reading the readme file on the git repository.

  4. Build a docker container for your code. PS: The following step creates a docker image which
    • Is based on a nodejs base image
    • Takes a copy of your code’s dependencies (that’s the package.json file for a nodejs app)
    • Downloads all those dependencies into a folder
    • Copies your code into the same folder
    • Declares the command that is used to run your code (node index.js in this case.)

    PS: My dockerhub username is karankapoor

     export DOCKER_USERNAME=<your-dockerhub-username>
     # building your container locally
     docker build -t $DOCKER_USERNAME/docker-workshop:latest -f Dockerfile .

    All the steps defined above, and more, such as setting environment variables, creating an image that depends on the output of multiple such images (aka multistage images) etc., is all defined in the Dockerfile file in the code you just checked out from github.

  5. Run the container locally, exposing the app on port 30000 of your local host machine

    docker run -d -p 30000:3000 --name my-app $DOCKER_USERNAME/docker-workshop:latest
    # inspect the docker container running in the background
    docker ps
  6. Explore your shiny new docker app in the browser

    http://localhost:30000/hello   # a GET endpoint that responds with some JSON content
  7. Clean up

    docker container stop $(docker container ls -aq)   # Stop all running containers

Pushing your first image to dockerhub

  1. Your first container for the world to see

    docker login   # it will ask you for your docker registry credentials. Since we're using dockerhub, no need to provide a registry URL
    docker push $DOCKER_USERNAME/docker-workshop:latest   # this will push your docker container to docker hub, kind of like a github for docker containers.

Now you’re a champ! But why stop here? If you installed docker desktop for your platform, most likely, you also have a local distribution of kubernetes running on your machine.

For more info on why you should consider orchestrating your container using kubernetes, and a basic how-to, follow the guide here.