kubernetes-controller-example

Hello, Kubernetes!

Purpose

This repository contains a super basic example for a custom kubernetes controller. The controller watches for new custom resources of kind example in the hello-k8s.s5t.dev apiGroup. Whenever a new example resource is created, the controller will spin-up a one-off pod which will simply print a date timestamp along with the famous hello, world example, only this one would say hello, k8s!. The entire code is written in Python and utilizies the official Python client for Kubernetes for any interaction with the Kubernetes API.

Running the controller

In order to run this example controller, you may either apply the provided manifests in k8s-manifests to your cluster (kubectl apply -f k8s-manifests/) Or simply run this controller locally on your machine. If you have Python3 installed, you may run python -u controller.py, or if you prefer the containerized way, you may build the docker image locally and run it, or simply pull the pre-built image from Dockerhub which updates the latest tag with every new update to this repository. NOTE - if you are running the controller on your local machine rather than in your cluster, you'll have to have:

1. A working .kube/config file pointing to the cluster in which you'd like to test this (current-context should point to the desired cluster).
2. Include the following environment variable in your controller runtime environment (either containerized or local) = AUTH_METHOD=local. This instructs the k8s client to pull the kubernetes api connection information from your local .kube/config file rather than the default cluster authentication method. (More information about this can bee seen in the k8s client authentication method), under _authenticate function.