Creating and Running a Docker Image of Your Website

Introduction

In the olden days, it would take hours to install and configure a web server on a local machine. It was especially fiddly if you wanted to recreate a specific environment for testing purposes. Happily, Docker has made our lives much easier.

In this tutorial, we’ll package a simple website and nginx server as a Docker image. Anyone with Docker Desktop installed can then run that site in seconds without having to set up anything.

For this to work, you’ll need Docker Desktop installed on your machine.

Creating Your Docker Image

First, let’s take a peek at the default behaviour of the nginx image. If you type: docker container run --publish 80:80 nginx at the command line, you’ll see nginx is running and serving its default page:

Default nginx page

Next, we’ll create our own version of this image and get it to display a (marginally) more exciting webpage.

To build an image, you’ll need to create a Dockerfile with the following contents:

FROM nginx:latest

WORKDIR /usr/share/nginx/html

COPY index.html index.html

In the FROM instruction, we’re specifying nginx:latest as the base layer.

Then we switch the WORKDIR (working directory) to /usr/share/nginx/html - the location where nginx is expecting to find webpages.

Finally, we COPY a local index.html file to the nginx container, giving it the same name.

As we’re using the nginx base layer, the CMD instruction (which tells the container what to do) is already specified.

That’s everything we need in our Dockerfile.

Of course, there should also be an index.html file.

I’m using a very simple example, which displays a random image from Unsplash:

<!DOCTYPE html>
<html lang="en">
<head>
    <title>Random Image</title>
</head>
<body>
    <h1>What will it be?</h1>
    <img src="https://source.unsplash.com/random" alt="Displays a random image from Unsplash">
</body>
</html>

Make sure your Dockerfile and index.html are in the same directory.

Now we can build the image:

docker image build -t my-web .

This command builds our image from the Dockerfile, giving it a name of my-web. The full stop (or period) tells Docker to look in the current directory for the Dockerfile.

A quick docker image ls command shows us the image is ready and waiting:

Tada! Image has been created

Running Your Docker Container

To run a container from our newly created image, use the following command:

docker container run --publish 80:80 my-web

We’re running the container on port 80 of localhost, and the container exposes port 80 (this was specified in the nginx base layer).

Visit localhost in your browser, and you’ll see your tiny website. If you used my index.html file, you’ll get a random image (hopefully it’s nothing rude).

Webpage served by nginx

To share your website with someone else, you can push your image to Docker Hub. There are three steps:

  1. Make sure you’re logged into Docker Hub (use docker login).
  2. Tag your image with your repository name. For example, I would use: docker image tag my-web catherinepope/my-web - this renames my-web to catherinepope/my-web.
  3. Push your image: docker image push catherinepope/my-web. Now anyone can use this image by referencing catherinepope/my-web.

If you’re just using the nginx container locally to test your website, there’s no need to create a new image. Instead, you can mount your local files onto the container:

docker container run -d --publish 80:80 -v $(pwd):/usr/share/nginx/html nginx

In this command:

  • the -v flag indicates we want to mount a local directory as a volume.
  • $(pwd) outputs the current working directory, where our HTML files are located. This is the source.
  • a colon : is followed by the location (or destination) on the container where we want to mount the directory. In this case, we’re using the nginx default /usr/share/nginx/html.
  • finally, we specify the nginx image.

Any web files you add to this directory are now accessible to your nginx server. If you update a file in this directory and hit refresh, you’ll see the new version in your browser.

Conclusion

That’s a very simple example of running a website with Docker. Hopefully, it’s enough to get you started with a more sophisticated build. Or you can just keep hitting refresh on your random image page.

Updated: