Docker Kata 1: Basic Commands
Learn about how to run a container and images.
Let’s get started with the first Docker kata. Each kata will be broken into steps. Below each command is a sample of the output that we should see when executing the command. Each step includes, after the commands, a breakdown of the commands and a summary of what they do.
Docker Kata 1 will introduce us to working with containers and images.
Step 1: Run the first container
The command to run the container is given below.
docker container run hello-world
The output will be something like this:
docker: This is the Docker Engine, which is the core Docker program.
Commands
Parameter | Description |
| Parent commands act on Docker objects such as containers, images, networks, etc. |
| Runs an image, creating an instance of a container. |
| This is an image. The |
This first command runs a container from an image. A Docker image is a blueprint for a container. Containers are running instances of an image.
The difference between an image and a container is the same as the difference between an executable (such as Notepad.exe) and the running program. Just as multiple instances of Notepad (and most other programs) can run side by side, various containers can be run at the same time, from the same image.
Note the first line of the output:
Unable to find image 'hello-world: latest' locally
Docker will first check the local image repository for the image indicated in the command. If the image is not found, it will check Docker Hub. Docker Hub is a public repository of images maintained by Docker Inc. The hello-world image is a test image stored on Docker Hub.
Image definitions include a start command. The start command runs a process inside the container when an ...