Chapter 3. First Steps

This chapter will guide you through your first steps with using Docker. We start by launching and using some simple containers to give you a feel for how Docker works. Then we move onto Dockerfiles—the basic building block of Docker containers—and Docker Registries, which support the distribution of containers. The chapter concludes with a look at how to use a container to host a key-value store with persistent storage.

Running Your First Image

To test that Docker is installed correctly, try running:

$ docker run debian echo "Hello World"

This may take a little while, depending on your Internet connection, but eventually you will get something similar to the following:

Unable to find image 'debian' locally
debian:latest: The image you are pulling has been verified
511136ea3c5a: Pull complete
638fd9704285: Pull complete
61f7f4f722fb: Pull complete
Status: Downloaded newer image for debian:latest
Hello World

So what’s happened here? We’ve called the docker run command, which is responsible for launching containers. The argument debian is the name of the image1 we want to use—in this case, a stripped-down version of the Debian Linux distribution. The first line of the output tells us we don’t have a local copy of the Debian image. Docker then checks online at the Docker Hub and downloads the newest version of the Debian image. Once the image has been downloaded, Docker turns the image into a running container and executes the command we specified— ...

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