Wallclock Operator for Kubernetes

This repository is just for up-skilling purposes with kubernetes operators and the Operator SDK in general.

Summary

The Wallclock operator creates two custom resources:

• Timezones
• Wallclocks

The manifests look like the following:

Timezones

apiVersion: clock.giorgos.com/v1
kind: Timezones
metadata:
  name: example-timezones
spec:
  clocks: 
    - GMT
    - CET
    - PST8PDT

Wallclocks

apiVersion: clock.giorgos.com/v1
kind: WallClock
metadata:
    name: example-timezones-pdt
spec:
    timezone: PDT
status:
    time: "15:00:00"

Whenever the operator finds out the there is one or more Timezone resources, it will check for its Spec to find out which Clocks exist.

It will then take the value of each clock (GMT, CET etc.) and create a Wallclock with the timezone and the actual time of the timezone based on the current UTC time.

Timezones

The timezones that are used for this operator are based on timezone data on the OS itself.

The alpine has been used to develop this operator. The image iteself has no timezone data by default, thats why you need to install them from your Dockerfile.

The dockerfile for this repo already does it for you using apk:

apk add tzdata

Once you install the timezone data in alpine, you can check them out under:

/usr/share/zoneinfo/

Local development

For local developemnt you will need a couple of things to get you starts.

1. Minikube
2. kubectl
3. Operator SDK

You can start minikube with this command : minikube start

Minikube will start a small local cluster that exists for testing purposes.

When your cluster is ready you should run the following commands to setup the cluster and the wallclock operator:

Setup Service Account:

kubectl create -f deploy/service_account.yaml

Setup RBAC

kubectl create -f deploy/role.yaml kubectl create -f deploy/role_binding.yaml

Setup Wallclock and Timezones

kubectl create -f deploy/crds/clock_v1_wallclock_crd.yaml kubectl create -f deploy/crds/clock_v1_timezones_crd.yaml

Create the operator

kubectl create -f deploy/operator.yaml

Testing

You can then start creating Timezones resource like so:

kubectl apply -f deploy/crds/clock_v1_timezones_cr.yaml

and the operator will start creating Wallclock resources based on the specification you provided.

You can check out the Wallclock resources like this:

kubectl get wallclocks