Parse a stream of kubernetes YAML on stdin into objects for reading

k8s_yaml_stream_parse.go

package main

import (
	"fmt"
	"io"
	"os"

	appsv1 "k8s.io/api/apps/v1"
	corev1 "k8s.io/api/core/v1"

	"k8s.io/apimachinery/pkg/runtime/serializer/json"
	"k8s.io/apimachinery/pkg/runtime/serializer/streaming"
	"k8s.io/client-go/kubernetes/scheme"
)

// Parse a stream of kubernetes YAML on stdin into objects for reading
func main() {
	yamlStreamReader := json.YAMLFramer.NewFrameReader(os.Stdin)
	decoder := streaming.NewDecoder(yamlStreamReader, scheme.Codecs.UniversalDeserializer())

	for {
		object, _, err := decoder.Decode(nil, nil)
		if err == io.EOF {
			break
		}

		if deployment, isDeployment := object.(*appsv1.Deployment); isDeployment {
			replicas := deployment.Spec.Replicas
			if replicas != nil {
				fmt.Printf("Deployment %s has %d replicas\n", deployment.ObjectMeta.Name, *replicas)
			}
		}

		if configMap, isConfigMap := object.(*corev1.ConfigMap); isConfigMap {
			fmt.Printf("ConfigMap %s has %d keys\n", configMap.ObjectMeta.Name, len(configMap.Data))
		}
	}
}