Creating Custom Ubuntu Containers in Docker

Written on Thu, 29 September 2016

Sometimes, you don't want to use any docker images created by community, but created your own, for many reasons:

• You built your own application and you want to make an image out of it
• You are using readily available images, but you made so much customisation you rather make a new container out of it
• You want to maintain your own image, maybe because the original author no longer maintains it

Whatever the reasons, let me guide you through the steps to create a new image from Ubuntu base.

Download Ubuntu Image

We are going to take the existing Ubuntu 16.04 image and configure it from there. The current latest Ubuntu version at the time of writing is 16.04.

docker pull ubuntu:16.04

You should see somewhat the following:

16.04: Pulling from library/ubuntu
cad964aed91d: Pull complete
3a80a22fea63: Pull complete
50de990d7957: Pull complete
61e032b8f2cb: Pull complete
9f03ce1741bf: Pull complete
Digest: sha256:28d4c5234db8d5a634d5e621c363d900f8f241240ee0a6a978784c978fe9c737
Status: Downloaded newer image for ubuntu:16.04

Next, run the image in bash

docker run -i -t ubuntu:16.04 /bin/bash

Let's make sure we update the ubuntu image with the latest patches:

apt-get update
apt-get dist-upgrade

Next, you may go ahead to install whatever application you want and customise it. Once you're down, you can exit the container.

exit

Generate an image from the container

Show the list of containers.

docker ps -a

It should look like this:

CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
9dbd13c7a5ba ubuntu:16.04 "/bin/bash" 33 minutes ago Exited (0) 10 minutes ago compassionate_joliot

Take note of the Container ID. You need it to make a new image

Next, we need to commit this as a new image.

docker commit 9dbd13c7a5ba newimagename:v1

Be sure to use your container ID and name the container accordingly.

You will now see the new image you've created when you list the images.

docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
newimagename v1 29d9cae9fdfd 9 minutes ago 166 MB
ubuntu 16.04 c73a085dc378 2 days ago 127 MB

Run the new docker image

Now run the newly created docker image

docker run -i -t newimagename:v1 /bin/bash

Substitute the name of the image name with yours.

There you go. You are now running an instance of the newly created image. Exit from the image and list the containers to see your achievement.

exit
docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
273f542f36e5 newimagename:v1 "/bin/bash" 14 seconds ago Exited (0) 10 seconds ago cranky_pike
9dbd13c7a5ba ubuntu:16.04 "/bin/bash" 43 minutes ago Exited (0) 19 minutes ago compassionate_joliot

You can see the new container is created from your new image.