How to create instance from snapshot

Hi guys, I did not find discussion forum or group so I'm asking here.

I have an VM instance in google cloud and I need to create many clones of the instance. So I created snapshot of instance's disk in Google Cloud Console. The console allows to create new instance based on snapshot, but I need to do it via GCloud Java API, how can I do that?

Thanks

@ukman

Hi @ukman,

On StackOverflow you can use the gcloud-java tag.
In general to see usage examples for gcloud-java you can have a look at our gcloud-java-examples module.
A detailed example of gcloud-java-compute features can be found in ComputeExample.java.
In CreateAddressDiskAndInstance.java you have an example of how to create an Instance after creating an Address and a Disk. You can follow that example and change the way the disk is created to create it from your Snapshot:

DiskId diskId = DiskId.of("us-central1-a", "test-disk");
SnapshotId snapshotId = SnapshotId.of("your-snapshot-id");
SnapshotDiskConfiguration diskConfiguration = SnapshotDiskConfiguration.of(snapshotId);
DiskInfo disk = DiskInfo.of(diskId, diskConfiguration);
operation = compute.create(disk);
// Wait for operation to complete
while (!operation.isDone()) {
  Thread.sleep(1000L);
}
// Check operation errors
operation = operation.reload();
if (operation.errors() == null) {
  System.out.println("Disk " + diskId + " was successfully created");
} else {
  // inspect operation.errors()
  throw new RuntimeException("Disk creation failed");
}

If you are not interested in creating a static address for your instance you can skip that part and create the instance as follows (notice that I remove the code to set the access configurations for the NetworkInterface):

InstanceId instanceId = InstanceId.of("us-central1-a", "test-instance");
NetworkId networkId = NetworkId.of("default");
PersistentDiskConfiguration attachConfiguration =
  PersistentDiskConfiguration.builder(diskId).boot(true).build();
AttachedDisk attachedDisk = AttachedDisk.of("dev0", attachConfiguration);
NetworkInterface networkInterface = NetworkInterface.builder(networkId).build();
MachineTypeId machineTypeId = MachineTypeId.of("us-central1-a", "n1-standard-1");
InstanceInfo instance =
  InstanceInfo.of(instanceId, machineTypeId, attachedDisk, networkInterface);
operation = compute.create(instance);
// Wait for operation to complete
while (!operation.isDone()) {
  Thread.sleep(1000L);
}
// Check operation errors
operation = operation.reload();
if (operation.errors() == null) {
  System.out.println("Instance " + instanceId + " was successfully created");
} else {
  // inspect operation.errors()
  throw new RuntimeException("Instance creation failed");
}

Hope this helps.

Marco, thanks a lot, it works!

Glad to here this. Please do not hesitate to contact us if you need help. Bug reports are more than welcome :)

Marco, do you have example for access configuration? I need external ephemeral IP for my VM, but cannot do this.
I found the following example, but it does not work.

  AccessConfig accessConfig = AccessConfig.builder().name("external-nat").build();
  compute.addAccessConfig(instance.instanceId(), "nic-0", accessConfig);

@ukman

Hi @ukman,

I believe that the default network interface for an instance is called nic0 (notice the missing "-"). You can verify this by checking compute.getInstance(instanceId). The following code should work:

AccessConfig accessConfig = AccessConfig.builder().name("external-nat").build();
compute.addAccessConfig(instance.instanceId(), "nic0", accessConfig);

Notice that you can also assign an ephemeral address at creation time (to spare one extra RPC call) with something like:

Compute compute = ComputeOptions.defaultInstance().service();
ImageId imageId = ImageId.of("debian-cloud", "debian-8-jessie-v20160329");
NetworkId networkId = NetworkId.of("default");
AttachedDisk attachedDisk =
    AttachedDisk.of(CreateDiskConfiguration.builder(imageId).autoDelete(true).build());
NetworkInterface networkInterface = NetworkInterface.builder(networkId)
    .accessConfigurations(NetworkInterface.AccessConfig.builder().name("external-nat").build())
    .build();
InstanceId instanceId = InstanceId.of("us-central1-a", "instance-name");
MachineTypeId machineTypeId = MachineTypeId.of("us-central1-a", "n1-standard-1");
Operation operation =
    compute.create(InstanceInfo.of(instanceId, machineTypeId, attachedDisk, networkInterface));
while (!operation.isDone()) {
    Thread.sleep(1000L);
}