import (
"context"
"fmt"
"io"
compute "cloud.google.com/go/compute/apiv1"
computepb "cloud.google.com/go/compute/apiv1/computepb"
"google.golang.org/protobuf/proto"
)
// createInstanceFromTemplate creates a Compute Engine VM instance from an instance template, but overrides the disk and machine type options in the template.
func createInstanceFromTemplateWithOverrides(w io.Writer, projectID, zone, instanceName, instanceTemplateName, machineType, newDiskSourceImage string) error {
// projectID := "your_project_id"
// zone := "europe-central2-b"
// instanceName := "your_instance_name"
// instanceTemplateName := "your_instance_template_name"
// machineType := "n1-standard-2"
// newDiskSourceImage := "projects/debian-cloud/global/images/family/debian-12"
ctx := context.Background()
instancesClient, err := compute.NewInstancesRESTClient(ctx)
if err != nil {
return fmt.Errorf("NewInstancesRESTClient: %w", err)
}
defer instancesClient.Close()
intanceTemplatesClient, err := compute.NewInstanceTemplatesRESTClient(ctx)
if err != nil {
return fmt.Errorf("NewInstanceTemplatesRESTClient: %w", err)
}
defer intanceTemplatesClient.Close()
// Retrieve an instance template by name.
reqGetTemplate := &computepb.GetInstanceTemplateRequest{
Project: projectID,
InstanceTemplate: instanceTemplateName,
}
instanceTemplate, err := intanceTemplatesClient.Get(ctx, reqGetTemplate)
if err != nil {
return fmt.Errorf("unable to get intance template: %w", err)
}
for _, disk := range instanceTemplate.Properties.Disks {
diskType := disk.InitializeParams.GetDiskType()
if diskType != "" {
disk.InitializeParams.DiskType = proto.String(fmt.Sprintf(`zones/%s/diskTypes/%s`, zone, diskType))
}
}
reqInsertInstance := &computepb.InsertInstanceRequest{
Project: projectID,
Zone: zone,
InstanceResource: &computepb.Instance{
Name: proto.String(instanceName),
MachineType: proto.String(fmt.Sprintf(`zones/%s/machineTypes/%s`, zone, machineType)),
Disks: append(
// If you override a repeated field, all repeated values
// for that property are replaced with the
// corresponding values provided in the request.
// When adding a new disk to existing disks,
// insert all existing disks as well.
instanceTemplate.Properties.Disks,
&computepb.AttachedDisk{
InitializeParams: &computepb.AttachedDiskInitializeParams{
DiskSizeGb: proto.Int64(10),
SourceImage: &newDiskSourceImage,
},
AutoDelete: proto.Bool(true),
Boot: proto.Bool(false),
Type: proto.String(computepb.AttachedDisk_PERSISTENT.String()),
},
),
},
SourceInstanceTemplate: instanceTemplate.SelfLink,
}
op, err := instancesClient.Insert(ctx, reqInsertInstance)
if err != nil {
return fmt.Errorf("unable to create instance: %w", err)
}
if err = op.Wait(ctx); err != nil {
return fmt.Errorf("unable to wait for the operation: %w", err)
}
fmt.Fprintf(w, "Instance created\n")
return nil
}
