README ¶
sample-controller
This repository implements a simple controller for watching Foo resources as defined with a CustomResourceDefinition (CRD).
This particular example demonstrates how to perform basic operations such as:
- How to register a new custom resource (custom resource type) of type
Foo
using a CustomResourceDefinition. - How to create/get/list instances of your new resource type
Foo
. - How to setup a controller on resource handling create/update/delete events.
It makes use of the generators in k8s.io/code-generator
to generate a typed client, informers, listers and deep-copy functions. You can
do this yourself using the ./hack/update-codegen.sh
script.
The update-codegen
script will automatically generate the following files &
directories:
pkg/apis/samplecontroller/v1alpha1/zz_generated.deepcopy.go
pkg/client/
Changes should not be made to these files manually, and when creating your own
controller based off of this implementation you should not copy these files and
instead run the update-codegen
script to generate your own.
Purpose
This is an example of how to build a kube-like controller with a single type.
Running
# assumes you have a working kubeconfig, not required if operating in-cluster
$ go run *.go -kubeconfig=$HOME/.kube/config
# create a CustomResourceDefinition
$ kubectl create -f artifacts/examples/crd.yaml
# create a custom resource of type Foo
$ kubectl create -f artifacts/examples/example-foo.yaml
# check deployments created through the custom resource
$ kubectl get deployments
Use Cases
CustomResourceDefinitions can be used to implement custom resource types for your Kubernetes cluster.
These act like most other Resources in Kubernetes, and may be kubectl apply
'd, etc.
Some example use cases:
- Provisioning/Management of external datastores/databases (eg. CloudSQL/RDS instances)
- Higher level abstractions around Kubernetes primitives (eg. a single Resource to define an etcd cluster, backed by a Service and a ReplicationController)
Defining types
Each instance of your custom resource has an attached Spec, which should be defined via a struct{}
to provide data format validation.
In practice, this Spec is arbitrary key-value data that specifies the configuration/behavior of your Resource.
For example, if you were implementing a custom resource for a Database, you might provide a DatabaseSpec like the following:
type DatabaseSpec struct {
Databases []string `json:"databases"`
Users []User `json:"users"`
Version string `json:"version"`
}
type User struct {
Name string `json:"name"`
Password string `json:"password"`
}
Cleanup
You can clean up the created CustomResourceDefinition with:
$ kubectl delete crd foos.samplecontroller.k8s.io
Compatibility
HEAD of this repository will match HEAD of k8s.io/apimachinery and k8s.io/client-go.
Where does it come from?
sample-controller
is synced from
https://github.com/kubernetes/kubernetes/blob/master/staging/src/k8s.io/sample-controller.
Code changes are made in that location, merged into k8s.io/kubernetes and
later synced here.
Documentation ¶
There is no documentation for this package.
Directories ¶
Path | Synopsis |
---|---|
pkg
|
|
apis/samplecontroller/v1alpha1
Package v1alpha1 is the v1alpha1 version of the API.
|
Package v1alpha1 is the v1alpha1 version of the API. |
client/clientset/versioned
This package has the automatically generated clientset.
|
This package has the automatically generated clientset. |
client/clientset/versioned/fake
This package has the automatically generated fake clientset.
|
This package has the automatically generated fake clientset. |
client/clientset/versioned/scheme
This package contains the scheme of the automatically generated clientset.
|
This package contains the scheme of the automatically generated clientset. |
client/clientset/versioned/typed/samplecontroller/v1alpha1
This package has the automatically generated typed clients.
|
This package has the automatically generated typed clients. |
client/clientset/versioned/typed/samplecontroller/v1alpha1/fake
Package fake has the automatically generated clients.
|
Package fake has the automatically generated clients. |