Go code that will connect to a production Kubernetes API if run in cluster, or to the whichever cluster you have `kubectl` configured to hit.

Kubernetes REST client configuration fallback.md

I find myself writing this a lot for code that I want to work in production, but also in a development environment.

This has been tested on k8s 1.2.2.

You must have the correct version of github.com/imdario/mergo vendored. Look at k8s.io/kubernetes/Godeps/Godeps.json to see which commit is used by Kubernetes.

TODO: add the vendor/manifest file that gb could use to restore vendored dependencies, since minimizing that just to get the code below to work is a monumental effort as well.

main.go

package main

import (
	"fmt"
	"log"

	"k8s.io/kubernetes/pkg/client/restclient"
	"k8s.io/kubernetes/pkg/client/unversioned"
	"k8s.io/kubernetes/pkg/client/unversioned/clientcmd"
)

func main() {
	cfg, err := findK8sConfig()
	if err != nil {
		log.Fatal(err)
	}

	client, err := unversioned.New(cfg)
	fmt.Printf("client=%v, err=%v\n", client, err)
}

func findK8sConfig() (cfg *restclient.Config, err error) {
	// Try in-cluster first
	if cfg, err = restclient.InClusterConfig(); err == nil {
		return cfg, nil
	}

	// Fall-back to local ~/.kube/config
	opts, err := clientcmd.NewDefaultClientConfigLoadingRules().Load()
	if err != nil {
		return nil, err
	}

	overrides := &clientcmd.ConfigOverrides{}
	return clientcmd.NewDefaultClientConfig(*opts, overrides).ClientConfig()
}