Pull an image.

docker pull ubuntu:20.04

Create a new container from the Ubuntu 20.04 image.

docker run -t -i ubuntu:20.04 /bin/bash

This will create a new container and attach to the bash shell as shown below:

root@013aecdd6919:/#

Now, install the Nginx package inside the container with the following command:

root@013aecdd6919:/# apt-get update -y
root@013aecdd6919:/# apt-get install nginx -y

Next, exit from the container with the following command:

root@013aecdd6919:/# exit

Next, locate your new container ID using the following command:

docker ps -a

You should get the container ID in the following output:

CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS                       PORTS               NAMES
013aecdd6919        ubuntu:20.04        "/bin/bash"         3 minutes ago       Exited (0) 33 seconds ago                        happy_camper

Next, save the updated container with a new image named nginx-instance using the following command:

docker commit "013aecdd6919" nginx-instance

• Where: 013aecdd6919 is the ID of the container.

You can now verify your newly created image “nginx-instance” with the following command:

docker images

You should get the following output:

REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
nginx-instance      latest              12cefc9b5362        57 seconds ago      158MB
ubuntu              20.04               d70eaf7277ea        12 days ago         72.9MB