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In this course, you’ll learn about containers, creating images, containerizing applications, and effectively deploying Docker in real-world scenarios.

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Containers have revolutionized the IT world, making it difficult to know where to begin. This course will take you from basics to proficiency step by step.
You’ll start by learning the basics of containers and how they work. Then, you’ll explore key concepts like images and the Docker engine. With the basics out of the way, you’ll learn how to containerize and run an application. After completing this course, you’ll be ready to use Docker in the real world.

Docker Guide for Beginners

The `docker run` command is the simplest and most common way to start a new container. Run the following command to start a new container called `webserver`.


$ docker run -d --name webserver -p 5005:8080 nigelpoulton/ddd-book:web0.1

Unable to find image 'nigelpoulton/ddd-book:web0.1' locally
web0.1: Pulling from nigelpoulton/ddd-book
4f4fb700ef54: Already exists
cf2a607f33f7: Download complete
0a1f0c111e9a: Download complete
c1af4b5db242: Download complete
Digest: sha256:3f5b281b914b1e39df8a1fbc189270a5672ff9e98bfac03193b42d1c02c43ef0
Status: Downloaded newer image for nigelpoulton/ddd-book:web0.1
b5594b3b8b3fdce544d2ca048e4340d176bce9f5dc430812a20f1852c395e96b

# Explanation

Let’s take a closer look at the command and the output:

- The `docker run` instructs Docker to run a new container.

- The `-d` flag tells Docker to run it in the background as a daemon process and detach from the local terminal.

- The `--name` flag tells Docker to name this container `webserver`. 

- The `-p 5005:8080` flag maps port `5005` on the local system to port `8080` inside the container. This works because the container’s web server is listening on port `8080`.

- The `nigelpoulton/ddd-book:web0.1` argument tells Docker which image to use to start the container.

# How it works
When we hit “Return,” the Docker client converts the command into an API request and posts it to the Docker API exposed by the Docker daemon. The Docker daemon accepts the command and searches its local image repository for a copy of the `nigelpoulton/ddd-book:web0.1` image. It doesn’t find one, so it searches Docker Hub. In the example, it finds one on Docker Hub and pulls a local copy.

Once it has a local copy of the image, the daemon makes a request to `containerd` asking for a new container. `containerd` then instructs `runc` to create the container and start the app. It also performs the port mapping.

Run the following commands to verify the image was pulled locally and a new container called `webserver` is running. 




Learn how to start a Docker container using the docker run command.

About the Course

An Overview of Containers

Docker and Container-Related Standards and Projects

The Big Picture

The Docker Engine

Working with Images

Working with Containers

Containerizing an Application

Conclusion

Appendix: Getting Docker

Starting a Container

Explanation