Getting Started
The command you just ran
Congratulations! You have started the container for this tutorial! Let's first explain the command that you just ran. In case you forgot, here's the command:
docker run -d -p 80:80 docker/getting-started
You'll notice a few Öags being used. Here's some more info on them:
-d - run the container in detached mode (in the background)
-p 80:80 - map port 80 of the host to port 80 in the container
docker/getting-started - the image to use
Pro tip
You can combine single character Öags to shorten the full command. As an example, the command above could be written as:
docker run -dp 80:80 docker/getting-started
The Docker Dashboard
Before going any further, we want to highlight the Docker Dashboard, which gives you a quick view of the containers running on your machine.
It provides you access to container logs, lets you get a shell inside the container, and allows you to easily manage container lifecycle (stop, remove, etc.)
To access the dashboard, follow the instructions in the Docker Desktop manual. If you open the dashboard now, you will see this tutorial running! The container name ( jolly_bouman below) is a randomly created name. So, you'll most likely have a diáerent name.
What is a container?
Now that you've successfully run a container, let's ask ourselves what is a container? Simply put, a container is another process on your machine that has been isolated from all other processes on the host machine. That isolation leverages kernel namespaces and groups, features that have been in Linux for a long time. Docker has worked to make these capabilities approachable and easy to use.
What is a container image?
When running a container, it uses an isolated filesystem. This custom system is provided by a container image.
Since the image contains the container's system, it must include everything needed to run the application - all dependencies, conÕguration, scripts, binaries, etc. The image also contains other conÕguration for the container, such as environment variables, a default command to run, and other metadata.
We'll dive deeper into images later on, covering topics such as layering, best practices, and more.
Info
If you're familiar with chroot , think of a container as an extended version of chroot . The Õlesystem is simply coming from the image whereas a container adds additional isolation that is not available when simply using chroot.