Google Cloud Storage Golang SignedURL for Resumeable upload

main.go

package main

import (
	"io/ioutil"
	"log"
	"time"

	"cloud.google.com/go/storage"
	//"golang.org/x/net/context"
)

const (
	projectID = "your_projectID"
)

func main() {

	bucketName := "your_bucket_name"
	fileName := "file.txt"
	method := "POST"
	expires := time.Now().Add(time.Second * 60)

	//ctx := context.Background()
	//client, err := storage.NewClient(ctx)
	//if err != nil {
	//	log.Fatalf("Failed to create client: %v", err)
	//}

	//https://github.com/GoogleCloudPlatform/google-cloud-go/blob/master/storage/storage.go#L173
  // remember to convert your service account .p12 to PEM format
	serviceAccountPEMFilename := "YOUR_SERVICE_ACCOUNT.pem"
	googleAccessID := "svc_account_name@your_project.iam.gserviceaccount.com"

	data, err := ioutil.ReadFile(serviceAccountPEMFilename)
	if err != nil {
		log.Fatalf("error: %v", err)
	}

	log.Printf("Getting upload url")
	opts := storage.SignedURLOptions{
		GoogleAccessID: googleAccessID,
		PrivateKey:     data,
		Method:         method,
		Expires:        expires,
		ContentType:    "text/plain",
		Headers:        []string{"x-goog-resumable:start"},
	}
	url, err := storage.SignedURL(bucketName, fileName, &opts)
	if err != nil {
		log.Fatalf("ERROR %v", err)
	}
	log.Println("SignedURL=", url)
}