in_cluster_namespace.go

package utils

import (
	"fmt"
	"io/ioutil"
	"os"
)

const inClusterNamespacePath = "/var/run/secrets/kubernetes.io/serviceaccount/namespace"

// returns the namespace in which the current process is executing, if running inside k8s
// else, return err
func GetInClusterNamesapce() (string, error) {
	// Check whether the namespace file exists.
	// If not, we are not running in cluster so can't guess the namespace.
	_, err := os.Stat(inClusterNamespacePath)
	if os.IsNotExist(err) {
		return "", fmt.Errorf("not running in-cluster, please specify LeaderElectionNamespace")
	} else if err != nil {
		return "", fmt.Errorf("error checking namespace file: %v", err)
	}

	// Load the namespace file and return its content
	namespace, err := ioutil.ReadFile(inClusterNamespacePath)
	if err != nil {
		return "", fmt.Errorf("error reading namespace file: %v", err)
	}
	return string(namespace), nil
}