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C# Basic Kubernetes Operator

The Basic Operator handles the MyResource custom resource. The operator simulates the interaction with an external service and can be used as a template for real-world operators.

Once the operator detects an added/modified event, it waits for 5 seconds and:

  • Adds a custom annotation custom-key in the object's metadata.annotation
  • Updates the status.actualProperty to match the spec.desiredProperty

See the implementation of MyResourceController.cs for more details.

Prerequisites

Running locally

  1. Add the custom resource definition to your Kubernetes cluster:

    $ cd csharp-operator-sdk/samples/basic
$ kubectl apply -f ./deploy/crds/crd.yaml

  2. Compile and run the operator:

    $ dotnet build
$ dotnet run

    The operator will connect to the Kubernetes cluster and will start watching for events. You'll see something similar to:

    <6>k8s.Operators.Operator[0] Start operator

  3. In another terminal, create a new MyResource object:

    $ kubectl apply -f ./deploy/crds/cr.yaml

    The operator will detect the new object and after 5 seconds will update the status to match the desired spec:

    <6>k8s.Operators.Controller[0] Begin AddOrModify default/mr1 (gen: 1), Spec: 1 Status: 
<6>k8s.Operators.Controller[0] End AddOrModify default/mr1 (gen: 1), Spec: 1 Status: 1

  4. Edit the resource and change the spec.desiredProperty to 2:

    $ kubectl edit myresources mr1
    apiVersion: csharp-operator.example.com/v1
kind: MyResource
:
spec:
  desiredProperty: 2
  :

    The operator will detect the change and will align again the status:

    <6>k8s.Operators.Controller[0] Begin AddOrModify default/mr1 (gen: 2), Spec: 2 Status: 1
<6>k8s.Operators.Controller[0] End AddOrModify default/mr1 (gen: 2), Spec: 2 Status: 2

  5. Delete the resource:

    $ kubectl delete myresources mr1

    The operator will simulate the deletion of the resource:

    <6>k8s.Operators.Controller[0] Begin Delete default/mr1 (gen: 3), Spec: 2 Status: 2
<6>k8s.Operators.Controller[0] End Delete default/mr1 (gen: 3), Spec: 2 Status: 2

  6. Shutdown the operator with CTRL+C or by sending a SIGTERM signal with:

    kill $(ps aux | grep '[k]8s.Operators.Samples.Basic' | awk '{print $2}')

    The operator will gracefully shutdown:

    <6>k8s.Operators.Operator[0] Stop operator
<6>k8s.Operators.Operator[0] Disposing operator

Deploy the operator in Kubernetes

  1. If you are running Minikube, point your shell to minikube's docker-daemon:

    $ eval $(minikube -p minikube docker-env)

  2. Create the docker image:

    $ cd csharp-operator-sdk
$ docker build -t csharp-basic-operator -f samples/basic/Dockerfile .

  3. Add the custom resource definition to your Kubernetes cluster:

    cd samples/basic
kubectl apply -f ./deploy/crds/crd.yaml

  4. Deploy the operator:

    kubectl apply -f ./deploy/service_account.yaml
kubectl apply -f ./deploy/role.yaml
kubectl apply -f ./deploy/role_binding.yaml
kubectl apply -f ./deploy/operator.yaml