exampleoperator

README

exampleoperator

This repository implements an example Kubernetes operator, called "ImmortalContainers". It's based on https://github.com/kubernetes/sample-controller. This operator enables the user to define, using custom resources, containers that must run and if terminated must be restarted.

Building

$ git clone git@github.com:flugel-it/exampleoperator.git $GOPATH/src/github.com/flugel-it/exampleoperator

$ make

Install CRD and RBAC permissions

To install CRDs and RBAC configurations to your currently set cluster use:

make install

Running the operator outside the cluster

./exampleoperator --kubeconfig ~/.kube/config

Running inside the cluster

You must first generate the image using make docker-build and push it to your repo.

If using minikube follow these steps:

eval $(minikube docker-env)
make docker-build

Then create the system namespace

kubectl apply -f config/namespace.yaml

And then run make deploy.

After this you should check that everything is running, ex:

$ kubectl get pods --namespace system                     
NAME                                          READY   STATUS    RESTARTS   AGE
exampleoperator-controller-7cb7f99658-97zjs   1/1     Running   0          24m

$ kubectl logs exampleoperator-controller-7cb7f99658-97zjs --namespace=system

I0221 19:47:51.036187       1 controller.go:115] Setting up event handlers
I0221 19:47:51.036509       1 controller.go:157] Starting ImmortalContainer controller
I0221 19:47:51.038034       1 controller.go:160] Waiting for informer caches to sync
I0221 19:47:51.138621       1 controller.go:165] Starting workers
I0221 19:47:51.138939       1 controller.go:171] Started workers
I0221 19:47:51.139358       1 controller.go:229] Successfully synced 'default/example-immortal-container'

Using the operator

Once the operator is running you can create immortal containers using a custom resource like this one:

apiVersion: exampleoperator.flugel.it/v1alpha1
kind: ImmortalContainer
metadata:
  name: example-immortal-container
spec:
  image: nginx:latest

Run kubectl apply -f config/example-use.yaml to try it.

Then run kubectl get pods and check the pod is created. If you kill the pod it will be recreated.

Remove the operator

To remove the operator, CDR and RBAC use make undeploy

Pods created by the operator will not be deleted, but will not be restarted if deleted later.