A simple Kubernetes Operator template that uses Golang, use it to build your own operators
A simple programmatic Kubernetes Operator template.
Use this to create your own Kubernetes operators with golang.
- Build with KIND (Kubernetes in Docker).
- Express custom behaviours in code - no DSL to learn.
- Generate your CRD's with controller-runtime and import them here.
- Works with built-in kubernetes resource types and custom resource definitions ( example included ).
- Works with Kubebuilder to write your own custom resource definitions, install them and operate with them.
- SlackAlerter is a complete example using this template.
Use this project template
- Click the
Use this templatebutton. - Open your new repo...
- Voila 💅🏼
Run the example... 🥰
Run builtin examples locally:
make upto start a K.I.N.D cluster on Docker.make run-builtin-example
./subscriptions
go run examples/builtin/main.go --kubeconfig=/Users/jonesax/.kube/config
I1111 16:03:11.903734 59945 main.go:51] Starting @ 2020-11-11 16:03:11.903596 +0000 GMT m=+0.008013710
I1111 16:03:11.903757 59945 main.go:52] Got watcher client...
I1111 16:03:11.944279 59945 exampledeploymentoperator.go:26] Deployment coredns has 2 Available replicas
I1111 16:03:11.945451 59945 examplepodoperator.go:29] Incoming pod event from kube-apiserver-kind-control-plane
I1111 16:03:11.946563 59945 exampledeploymentoperator.go:26] Deployment local-path-provisioner has 1 Available replicas
I1111 16:03:11.946968 59945 exampledeploymentoperator.go:26] Deployment chart-1605110531-kubeops has 1 Available replicas
I1111 16:03:11.947272 59945 exampledeploymentoperator.go:26] Deployment chart-1605044953-kubeops has 1 Available replicas
I1111 16:03:11.947625 59945 examplepodoperator.go:29] Incoming pod event from kindnet-dmqg9
I1111 16:03:11.948102 59945 examplepodoperator.go:29] Incoming pod event from kube-proxy-qvqpm
I1111 16:03:11.948603 59945 examplepodoperator.go:29] Incoming pod event from coredns-f9fd979d6-2472d
I1111 16:03:11.948863 59945 examplepodoperator.go:29] Incoming pod event from chart-1605110531-kubeops-6957c9d5df-glhxf
I1111 16:03:11.950408 59945 examplepodoperator.go:29] Incoming pod event from coredns-f9fd979d6-vfcd7
I1111 16:03:11.950854 59945 examplepodoperator.go:29] Incoming pod event from chart-1605044953-kubeops-9645784f5-l6xlc
I1111 16:03:11.951771 59945 examplepodoperator.go:29] Incoming pod event from etcd-kind-control-plane
I1111 16:03:11.952974 59945 examplepodoperator.go:29] Incoming pod event from kube-scheduler-kind-control-plane
I1111 16:03:11.953784 59945 examplepodoperator.go:29] Incoming pod event from kube-controller-manager-kind-control-plane
I1111 16:03:11.954150 59945 examplepodoperator.go:29] Incoming pod event from local-path-provisioner-78776bfc44-skrmbResources to watch
runtime.EventBuffer(ctx, kubeClient, registry,[]watcher.IObject{
// Buffer events for these built-in types kubeClient.CoreV1().Pods(""), kubeClient.AppsV1().Deployments(""), kubeClient.CoreV1().ConfigMaps(""), //Example CRD imported into the runtime----------------------------------------------------------- //exampleClient.SamplecontrollerV1alpha1().Foos(""), // ----------------------------------------------------------------------------------------------- })
Subscriptions on the watched resources
registry := &subscription.Registry{
Subscriptions: []subscription.ISubscription{
// Subscribe to these built-in type events
subscriptions.ExamplePodOperator{},
subscriptions.ExampleFooCRDOperator{},
subscriptions.ExampleDeploymentOperator{},
},
}Build docker image and install into cluster locally:
make
Please see REQUIREMENTS.md for installation requirements_
Please see LICENCE.md for licence enquiries_
Development perks
- A simple golang based implementation of an Operator with the boiler plate done.
- Has a pre-made helm chart, so you can build an image of this code and push it into a cluster with your changes.
- Example of using k8s golang API
- Example of using helm
Commands
| | | |---|---| | make up | Creates a kind cluster | | make run-builtin-example | Runs the ./examples/builtin/main.go | | make run-crd-example | Runs the ./examples/crd/main.go | | make down | Deletes the kind cluster | | make | Builds the project, dockerfile, side loads then installs into the cluster | | make delete | Deletes all currently installed helm releases |
Suggested development workflow
<write some code>
- Test with the above steps.
make
- View your changes in the cluster
- If you like it, push the docker image with the kubeops image and use the helm chart to install it
cd helm && helm install . --generate-name
How does it work in a nutshell? 🐣
- Kubeops uses the go-client for Kubernetes and leverages the watch capability.
- The value of this project is wrapping those calls in interfaces and creating some utility functionality for cluster connection.
- More information on how to develop your own operator watchers/subscriptions can be found here.
What about Custom Resource Definitions?
Currently the solution would be to use kubebuilder to generate CRD's and then import them either as a library or subproject into KubeOps template.
