Generate OpenAPI definitions

• To generate definition for a specific type or package add "+k8s:openapi-gen=true" tag to the type/package comment lines.
• To exclude a type or a member from a tagged package/type, add "+k8s:openapi-gen=false" tag to the comment lines.

OpenAPI Extensions

OpenAPI spec can have extensions on types. To define one or more extensions on a type or its member add +k8s:openapi-gen=x-kubernetes-$NAME:$VALUE`` to the comment lines before type/member. A type/member can have multiple extensions. The rest of the line in the comment will be used as $VALUE so there is no need to escape or quote the value string. Extensions can be used to pass more information to client generators or documentation generators. For example a type might have a friendly name to be displayed in documentation or being used in a client's fluent interface.

Custom OpenAPI type definitions

Custom types which otherwise don't map directly to OpenAPI can override their OpenAPI definition by implementing a function named "OpenAPIDefinition" with the following signature:

import openapi "k8s.io/kube-openapi/pkg/common"

// ...

type Time struct {
	time.Time
}

func (_ Time) OpenAPIDefinition() openapi.OpenAPIDefinition {
	return openapi.OpenAPIDefinition{
		Schema: spec.Schema{
			SchemaProps: spec.SchemaProps{
				Type:   []string{"string"},
				Format: "date-time",
			},
		},
	}
}

Alternatively, the type can avoid the "openapi" import by defining the following methods. The following example produces the same OpenAPI definition as the example above:

func (_ Time) OpenAPISchemaType() []string { return []string{"string"} }
func (_ Time) OpenAPISchemaFormat() string { return "date-time" }

TODO(mehdy): Make k8s:openapi-gen a parameter to the generator now that OpenAPI has its own repo.