Simple App Containerization hands-on lab with Docker

Lifecycle of a container

Images of containers are immutable. (i.e. when you start a container, and make file modifications, it does not modify the original image.) However, you can create a new image based off of the modified container.

Start and modify a Ubuntu container

Start an Ubuntu Container:

docker run -it ubuntu /bin/bash

Make a change to the container and exit

touch /tmp/foo
ls /tmp/foo

Notice the file

exit

Start the container again

docker run -it ubuntu /bin/bash
ls /tmp/foo

Now we will start a new image of Ubuntu and save it.

Start an Ubuntu Container:

docker run -it ubuntu /bin/bash

Make a change to the container and exit

touch /tmp/foo
ls /tmp/foo

IN A NEW WINDOW, with the container still running:

docker ps -a | head -2
docker diff <Container ID>

Commit the container

docker commit <Container ID> ubuntu-foo
docker run -it ubuntu-foo /bin/bash
ls /tmp/foo

Now the file exists

Lab Navigation

1. Lab Overview
2. Installing Docker locally
3. Running a simple app in a Docker container locally
4. Lifecycle of a container <– You are here
5. Creating and running Docker images using a Dockerfile
6. Defining and running multi-container Docker applications using Docker compose
7. Running CAT Sample App locally

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