How to create multi instance in google cloud functions with golang

I am trying to create multi instance in GCP with cloud function, use golang programing.

I refer tutorial in https://medium.com/google-cloud/using-cloud-scheduler-and-cloud-functions-to-deploy-a-periodic-compute-engine-vm-worker-2b897ef68dc5 then write some customize in my context. Here is my code

package cloudfunctions
import (
"context"
"fmt"
"log"
"net/http"
"os"
"google.golang.org/api/compute/v1"
)
var ProjectID = ""
var Zone = ""
var Region = ""
var InstanceName = ""
var InstanceType = ""
func DeployInstance(w http.ResponseWriter, r *http.Request) {
ProjectID = os.Getenv("PROJECT_ID")
Zone = os.Getenv("ZONE")
Region = os.Getenv("REGION")
cs, err := InitComputeService()
if err != nil {
w.WriteHeader(http.StatusInternalServerError)
log.Fatal(err)
}
var listInstance = []string{"e2-standard-2", "e2-standard-8", "n2-standard-2", "n2-standard-8", "n1-custom-2-8192", "n1-custom-8-32768", "c2-standard-8" }
for i:=0; i < 7; i++ {
InstanceType = listInstance[i]
InstanceName = "benchmark-"+InstanceType
instance, err := GetInstance(cs)
if err != nil {
w.WriteHeader(http.StatusTemporaryRedirect)
w.Write([]byte(err.Error() + " instance may not exist yet"))
log.Print(err)
_, err = CreateInstance(cs)
if err != nil {
w.WriteHeader(http.StatusInternalServerError)
w.Write([]byte("creating instance " + InstanceName + "in zone: " + Zone))
startInstance(cs, w)
}
} else {
msg := "instance is in intermediate state: " + instance.Status
w.WriteHeader(http.StatusAccepted)
w.Write([]byte(msg))
log.Println(msg)
}
}
}
func InitComputeService() (*compute.Service, error) {
ctx := context.Background()
return compute.NewService(ctx)
}
func GetInstance(computeService *compute.Service) (*compute.Instance, error) {
return computeService.Instances.Get(ProjectID, Zone, InstanceName).Do()
}
func StartInstance(computeService *compute.Service) (*compute.Operation, error) {
return computeService.Instances.Start(ProjectID, Zone, InstanceName).Do()
}
// CreateInstance creates a given instance with metadata that logs its information.
func CreateInstance(computeService *compute.Service) (*compute.Operation, error) {
instance := &compute.Instance{
Name: InstanceName,
MachineType: fmt.Sprintf("zones/%s/machineTypes/%s", Zone, InstanceType),
NetworkInterfaces: []*compute.NetworkInterface{
{
Name:       "default",
Subnetwork: fmt.Sprintf("projects/%s/regions/%s/subnetworks/default", ProjectID, Region),
AccessConfigs: []*compute.AccessConfig{
{
Name:        "External NAT",
Type:        "ONE_TO_ONE_NAT",
NetworkTier: "PREMIUM",
},
},
},
},
Scheduling: &compute.Scheduling{
Preemptible: true,
},
Disks: []*compute.AttachedDisk{
{
Boot:       true,         // The first disk must be a boot disk.
AutoDelete: true,         //Optional
Mode:       "READ_WRITE", //Mode should be READ_WRITE or READ_ONLY
Interface:  "SCSI",       //SCSI or NVME - NVME only for SSDs
InitializeParams: &compute.AttachedDiskInitializeParams{
DiskName: "worker-instance-boot-disk",
SourceImage: "projects/centos-cloud/global/images/family/centos-7",
DiskType:    fmt.Sprintf("projects/%s/zones/%s/diskTypes/pd-ssd", ProjectID, Zone),
DiskSizeGb:  200,
},
},
},
}
return computeService.Instances.Insert(ProjectID, Zone, instance).Do()
}
// startInstance is a wrapper function for the switch statement
func startInstance(cs *compute.Service, w http.ResponseWriter) {
operation, err := StartInstance(cs)
if err != nil {
w.WriteHeader(http.StatusInternalServerError)
log.Fatal(err)
}
w.WriteHeader(http.StatusOK)
data, _ := operation.MarshalJSON()
w.Write(data)
}

In above code, I want to create 7 instance with 7 difference setting, specific is instance type and instance name. I test this code in cloud function with DeployInstance is start function. But there is only one instance was created, with name is benchmark-e2-standard-2 and type is e2-standard-2. It output an error with message Error: Infrastructure cannot communicate with function. There was likely a crash or deadlock in the user-provided code. Additional troubleshooting documentation can be found at https://cloud.google.com/functions/docs/troubleshooting#logging

I visited website but I not find a solution to fix my code. Who can help me why my code not true, how can I fix it. Step by step if possible.
Thanks in advance.

I was found my answer. Root cause is each instance must have a disk partition, with different name.
So, I change my code with some change, you can see it bellow.

package cloudfunctions

import (
	"context"
	"fmt"
	"log"
	"net/http"
	"os"
	"google.golang.org/api/compute/v1"
	"time"
)

var ProjectID = ""
var Zone = ""
var Region = ""
var InstanceName = ""
var InstanceType = ""
var IDiskName = ""

func DeployInstance(w http.ResponseWriter, r *http.Request) {
	ProjectID = os.Getenv("PROJECT_ID")
	Zone = os.Getenv("ZONE")
	Region = os.Getenv("REGION")

	var listInstance = []string{"e2-standard-8","e2-standard-2",  "n2-standard-2", "n2-standard-8", "n1-custom-2-8192", "n1-custom-8-32768", "c2-standard-8"}
	for i:=0; i < len(listInstance); i++ {
		cs, err := compute.NewService(context.Background())
		if err != nil {
			w.WriteHeader(http.StatusInternalServerError)
			log.Fatal(err)
		}
		InstanceType = listInstance[i]
		InstanceName = "benchmark-"+InstanceType
		IDiskName = InstanceName+"-boot-disk"

		instance, err := GetInstance(cs)
		if err != nil {
			w.WriteHeader(http.StatusTemporaryRedirect)
			w.Write([]byte(err.Error() + " instance may not exist yet"))

			_, err = CreateInstance(cs)
			if err != nil {
				for {
					disk, derr := cs.Disks.Get(ProjectID, Zone, IDiskName).Context(context.Background()).Do()
					log.Print(IDiskName + " is " + disk.Status)
					time.Sleep(1 * time.Second)
					if derr != nil {
						startInstance(cs, w)
						break
					}
				}
				
			}
		} else {
			msg := "instance "+ InstanceName +" is in intermediate state: " + instance.Status
			w.WriteHeader(http.StatusAccepted)
			w.Write([]byte(msg))
			log.Println(msg)
		}
	}
}


func GetInstance(computeService *compute.Service) (*compute.Instance, error) {
	return computeService.Instances.Get(ProjectID, Zone, InstanceName).Do()
}


func StartInstance(computeService *compute.Service) (*compute.Operation, error) {
	return computeService.Instances.Start(ProjectID, Zone, InstanceName).Do()
}

// CreateInstance creates a given instance with metadata that logs its information.
func CreateInstance(computeService *compute.Service) (*compute.Operation, error) {
	instance := &compute.Instance{
		Name: InstanceName,
		MachineType: fmt.Sprintf("zones/%s/machineTypes/%s", Zone, InstanceType),
		NetworkInterfaces: []*compute.NetworkInterface{
			{
				Name:       "default",
				Subnetwork: fmt.Sprintf("projects/%s/regions/%s/subnetworks/default", ProjectID, Region),
				AccessConfigs: []*compute.AccessConfig{
					{
						Name:        "External NAT",
						Type:        "ONE_TO_ONE_NAT",
						NetworkTier: "PREMIUM",
					},
				},
			},
		},
		Scheduling: &compute.Scheduling{
			Preemptible: true,
		},
		Disks: []*compute.AttachedDisk{
			{
				Boot:       true,         // The first disk must be a boot disk.
				AutoDelete: true,         //Optional
				Mode:       "READ_WRITE", //Mode should be READ_WRITE or READ_ONLY
				Interface:  "SCSI",       //SCSI or NVME - NVME only for SSDs
				InitializeParams: &compute.AttachedDiskInitializeParams{
					DiskName: IDiskName,
					SourceImage: "projects/centos-cloud/global/images/family/centos-7",
					DiskType:    fmt.Sprintf("projects/%s/zones/%s/diskTypes/pd-ssd", ProjectID, Zone),
					DiskSizeGb:  100,
				},
			},
		},
	}
	return computeService.Instances.Insert(ProjectID, Zone, instance).Do()
}

// startInstance is a wrapper function for the switch statement
func startInstance(cs *compute.Service, w http.ResponseWriter) {
	operation, err := StartInstance(cs)
	if err != nil {
		w.WriteHeader(http.StatusInternalServerError)
		log.Fatal(err)
	}
	w.WriteHeader(http.StatusOK)
	data, _ := operation.MarshalJSON()
	w.Write(data)
}

If you have any question about this problem, drop your comment. I hope I can support for you.
Thanks all.