cri-o/vendor/k8s.io/client-go/examples/third-party-resources

Third Party Resources Example

This particular example demonstrates how to perform basic operations such as:

• How to register a new ThirdPartyResource (custom Resource type)
• How to create/get/list instances of your new Resource type (update/delete/etc work as well but are not demonstrated)

Running

# assumes you have a working kubeconfig, not required if operating in-cluster
go run *.go -kubeconfig=$HOME/.kube/config

Use Cases

ThirdPartyResources 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 ThirdPartyResource 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 ThirdPartyResource 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"`
}