Docker Static Site | DevSecOps for BBK

Last updated 1 year ago

2.0 Webapps with Docker

Great! So you have now looked at docker run, played with a Docker container and also got the hang of some terminology. Armed with all this knowledge, you are now ready to get to the real stuff — deploying web applications with Docker.

2.1 Run a static website in a container

Note: Code for this section is in this repo in the .

Let's start by taking baby-steps. First, we'll use Docker to run a static website in a container. The website is based on an existing image. We'll pull a Docker image from Docker Store, run the container, and see how easy it is to set up a web server.

The image that you are going to use is a single-page website that was already created for this demo and is available on the Docker Store as . You can download and run the image directly in one go using docker run as follows.

Note: The current version of this image doesn't run without the -d flag. The -d flag enables detached mode, which detaches the running container from the terminal/shell and returns your prompt after the container starts. We are debugging the problem with this image but for now, use -d even for this first example.

So, what happens when you run this command?

Since the image doesn't exist on your Docker host, the Docker daemon first fetches it from the registry and then runs it as a container.

Now that the server is running, do you see the website? What port is it running on? And more importantly, how do you access the container directly from our host machine?

Actually, you probably won't be able to answer any of these questions yet! ☺ In this case, the client didn't tell the Docker Engine to publish any of the ports, so you need to re-run the docker run command to add this instruction.

Let's re-run the command with some new flags to publish ports and pass your name to the container to customize the message displayed. We'll use the -d option again to run the container in detached mode.

First, stop the container that you have just launched. In order to do this, we need the container ID.

Since we ran the container in detached mode, we don't have to launch another terminal to do this. Run docker ps to view the running containers.

Check out the CONTAINER ID column. You will need to use this CONTAINER ID value, a long sequence of characters, to identify the container you want to stop, and then to remove it. The example below provides the CONTAINER ID on our system; you should use the value that you see in your terminal.

Note: A cool feature is that you do not need to specify the entire CONTAINER ID. You can just specify a few starting characters and if it is unique among all the containers that you have launched, the Docker client will intelligently pick it up.

Now, let's launch a container in detached mode as shown below:

In the above command:

-d will create a container with the process detached from our terminal
-P will publish all the exposed container ports to random ports on the Docker host
-e is how you pass environment variables to the container
--name allows you to specify a container name
AUTHOR is the environment variable name and Your Name is the value that you can pass

Now you can see the ports by running the docker port command.

If you are using Docker Machine on Mac or Windows, you can find the hostname on the command line using docker-machine as follows (assuming you are using the default machine).

You can now open http://<YOUR_IPADDRESS>:[YOUR_PORT_FOR 80/tcp] to see your site live! For our example, this is: http://192.168.99.100:32773.

You can also run a second webserver at the same time, specifying a custom host port mapping to the container's webserver.

To deploy this on a real server you would just need to install Docker, and run the above docker command(as in this case you can see the AUTHOR is Docker which we passed as an environment variable).

Now that you've seen how to run a webserver inside a Docker container, how do you create your own Docker image? This is the question we'll explore in the next section.

But first, let's stop and remove the containers since you won't be using them anymore.

Let's use a shortcut to remove the second site:

Run docker ps to make sure the containers are gone.

2.2 Docker Images

In this section, let's dive deeper into what Docker images are. You will build your own image, use that image to run an application locally, and finally, push some of your own images to Docker Cloud.

Docker images are the basis of containers. In the previous example, you pulled the dockersamples/static-site image from the registry and asked the Docker client to run a container based on that image. To see the list of images that are available locally on your system, run the docker images command.

Above is a list of images that I've pulled from the registry and those I've created myself (we'll shortly see how). You will have a different list of images on your machine. The TAG refers to a particular snapshot of the image and the ID is the corresponding unique identifier for that image.

For example you could pull a specific version of ubuntu image as follows:

If you do not specify the version number of the image then, as mentioned, the Docker client will default to a version named latest.

So for example, the docker pull command given below will pull an image named ubuntu:latest:

An important distinction with regard to images is between base images and child images.

Base images are images that have no parent images, usually images with an OS like ubuntu, alpine or debian.
Child images are images that build on base images and add additional functionality.

Another key concept is the idea of official images and user images. (Both of which can be base images or child images.)

User images are images created and shared by users like you. They build on base images and add additional functionality. Typically these are formatted as user/image-name. The user value in the image name is your Docker Store user or organization name.

Last updated 1 year ago