For this example we're going to be using Jason Haley's hello world Python Flask Application because its quite a neat little application to show how requirements can be used and how you can build an application with some dependencies.

Create a directory for it first under the "ubuntu" home directory.

Let's clone Jason's Git Repository into the directory:

So now let's install the requirements for Python as per what is in the requirements.txt file from the Git Repo.

Now run the application:

Then you can either run the above as a background task by adding & to the end or open another SSH session to your master node then run the following, you get "Hello from Python!" back, the application is working!

So that looks to be working!

Okay now we know the application works, lets create a docker file to start to build our image.

Create a file called "Dockerfile", and put this in it:

Now create the image:

Wait for it to build, once it has been built, run the following to list the Docker images:

As you can see there it is:

Right quick explanation of the above, we created Docker image that includes the Python application wrapped up in Flask (so its a web site essentially), we then build the Docker file and add the tag "hello-python:local" (more about tags in a later guide). Also notice that the application is set within the Dockerfile to expose port 5000, what that means is that when the image is deployed in Kubernetes it will present port 5000 to within Kubernetes, we can then decide when presenting out the application what port we want used for the outside world.

Now its running you should see something like:

Okay so now from another terminal run: