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In this lesson you start your first container, look at it, and remove it. The container runs hello-world, a tiny official test image whose only job is to print a message and stop. Every command below is typed in the terminal you opened in the What is Docker? lesson.

The image tag is latest, the default for hello-world. It is the only image in this course that uses that tag, because its output never changes. The options of the docker run command are described in the docker run reference.

Step 1: Check that Docker answers

Type this command and press Enter:

docker version

You should see a Client part and a Server part, as in the Install Docker lesson. If the Server part is missing or an error appears, start Docker Desktop or the Docker service, then try again.

Step 2: Run the test container

Type this command and press Enter:

docker run hello-world

The first time, Docker first prints Unable to find image 'hello-world:latest' locally and downloads the image. Then the container starts, prints a message and stops. The message starts with:

Hello from Docker!
This message shows that your installation appears to be working correctly.

The container has finished its work and is stopped. It still exists on your computer, which you will see in the next steps.

Step 3: List the running containers

Type this command and press Enter:

docker ps

docker ps lists only containers that are running right now. Because hello-world has already stopped, you do not see it here. If you have never started a container before, the list shows only the header line:

CONTAINER ID   IMAGE     COMMAND   CREATED   STATUS    PORTS     NAMES

If Docker has been used on your computer before, other containers may appear in this list. That is normal.

Step 4: List all containers, including stopped ones

Type this command and press Enter:

docker ps -a

The -a option means all. The list now includes your stopped hello-world container. Its row looks similar to this:

CONTAINER ID   IMAGE         COMMAND   CREATED         STATUS                     PORTS     NAMES
3c1f0a9e2b7d   hello-world   "/hello"  2 minutes ago   Exited (0) 2 minutes ago             happy_turing

Find the row whose IMAGE is hello-world. Read its NAMES value, which is a random name such as happy_turing. Your name will be different. The STATUS Exited (0) means the container finished with no error. A number other than 0 would mean it failed.

Step 5: Remove the container

Use the name from the NAMES column of your own row. Type docker rm followed by that name, for example:

docker rm happy_turing

Docker prints the name again, which confirms the container was removed. Run docker ps -a once more and check that your hello-world row has gone. Removing a container does not remove the image, so the next run starts faster.

What you learned

• docker run creates a container from an image and starts it.
• A container stops when its program finishes, but it stays on your computer until you remove it.
• docker ps shows running containers, and docker ps -a shows all of them.
• docker rm removes a stopped container by its name.

What comes next

Go on to Run Nginx, where a container serves a web page to your browser.