So, you know you want to run your application in Kubernetes but don’t know where to start. Or maybe you’re getting started but still don’t know what you don’t know. In this blog you’ll walk through how to containerize an application and get it running in Kubernetes.

This walk-through assumes you are a developer or at least comfortable with the command line (preferably bash shell).

What we’ll do

1. Get the code and run the application locally
2. Create an image and run the application in Docker
3. Create a deployment and run the application in Kubernetes

Prerequisites

• A Kubernetes service - I’m using Docker Desktop with Kubernetes in this walkthrough, but you can use one of the others. See Getting Started for a full listing.
• Python 3.7 installed
• Git installed

Containerizing an application

In this section you’ll take some source code, verify it runs locally, and then create a Docker image of the application. The sample application used is a very simple Flask web application; if you want to test it locally, you’ll need Python installed. Otherwise, you can skip to the “Create a Dockerfile” section.

Get the application code

Use git to clone the repository to your local machine:

git clone https://github.com/JasonHaley/hello-python.git

Change to the app directory:

cd hello-python/app

There are only two files in this directory. If you look at the main.py file, you’ll see the application prints out a hello message. You can learn more about Flask on the Flask website.

from flask import Flask
app = Flask(__name__)

@app.route("/")
def hello():
    return "Hello from Python!"

if __name__ == "__main__":
    app.run(host='0.0.0.0')

The requirements.txt file contains the list of packages needed by the main.py and will be used by pip to install the Flask library.

#python #kubernetes