CODEWITHSUNDEEP
node.jskernelgoogle-compute-enginestartupgcloud
Gabriel Petrovay
Gabriel Petrovay

Reputation: 21944

Is there a gcloud API to detect when a Compute Engine server is completely up?

I create an VM instance. I can connect to it as soon ad the SSH Daemon is started. But this is too early because kernel startup is only at approx. 30%. Is there a gcloud or other API to get the VM state when the kernel has finished startup?

Nov 18 10:58:51 image-name google: No startup script found in metadata.
Nov 18 10:58:53 image-name kernel: [   27.491829] aufs au_opts_verify:1570:docker[2414]: dirperm1 breaks the protection by the permission bits on the lower branch
Nov 18 10:58:53 image-name kernel: [   27.703142] aufs au_opts_verify:1570:docker[2414]: dirperm1 breaks the protection by the permission bits on the lower branch
Nov 18 10:58:53 image-name kernel: [   27.735867] aufs au_opts_verify:1570:docker[2414]: dirperm1 breaks the protection by the permission bits on the lower branch
Nov 18 10:58:53 image-name kernel: [   27.771732] aufs au_opts_verify:1570:docker[2260]: dirperm1 breaks the protection by the permission bits on the lower branch
Nov 18 10:58:53 image-name kernel: [   27.797540] device vethfa3ab85 entered promiscuous mode
Nov 18 10:58:53 image-name kernel: [   27.804420] IPv6: ADDRCONF(NETDEV_UP): vethfa3ab85: link is not ready
Nov 18 10:58:53 image-name kernel: [   28.028306] IPv6: ADDRCONF(NETDEV_CHANGE): vethfa3ab85: link becomes ready
Nov 18 10:58:53 image-name kernel: [   28.035505] docker0: port 1(vethfa3ab85) entered forwarding state
Nov 18 10:58:53 image-name kernel: [   28.041963] docker0: port 1(vethfa3ab85) entered forwarding state
Nov 18 10:58:53 image-name kernel: [   28.048532] IPv6: ADDRCONF(NETDEV_CHANGE): docker0: link becomes ready
Nov 18 10:58:54 image-name kernel: [   28.980082] IPv6: eth0: IPv6 duplicate address fe80::42:acff:fe11:1 detected!
->>> about here I can SSH to the server
Nov 18 10:59:08 image-name kernel: [   43.068094] docker0: port 1(vethfa3ab85) entered forwarding state
Nov 18 10:59:53 image-name kernel: [   87.944452] aufs au_opts_verify:1570:docker[2864]: dirperm1 breaks the protection by the permission bits on the lower branch
Nov 18 10:59:53 image-name kernel: [   88.001012] aufs au_opts_verify:1570:docker[2864]: dirperm1 breaks the protection by the permission bits on the lower branch
Nov 18 10:59:53 image-name kernel: [   88.049510] aufs au_opts_verify:1570:docker[2815]: dirperm1 breaks the protection by the permission bits on the lower branch
->>> I want to know about this point in the startup process

My problem is that I can connect to it using SSH when kernel progress is below 30% and some processes are not yet started. I want to detect somehow if the server has completed startup. Or is there a script that can push to the server (through the GCE APIs) to notify me when a server is completely up?

gcloud compute instances describe image-name does return the same output from the moment the instance is started till the kernel startup is complete.

(In my case I use the Node.js GCE API, but this should not make any difference.)

Upvotes: 1

Views: 195

Answers (2)

Tom
Tom

Reputation: 1291

Similar to Kamran, but here is how I get this done. It depends on using a google startup script and an image where gcloud is installed by default (though you could rework this to just use curl and API calls)

On instance creation/configuration, I set a custom metadata flag: serverready=False

At the end of my google startup script, I have this:

sudo gcloud compute instances add-metadata $(hostname) \ --metadata serverready=True \ --zone $(curl \ "http://metadata.google.internal/computeMetadata/v1/instance/zone" \ -H "Metadata-Flavor: Google"|cut -d/ -f4)

When I run the instance creation, I can just poll the metadata for the serverready key, and set my app to wait until it sees serverready=True

Upvotes: 0

Raghav
Raghav

Reputation: 521

Presently I am not aware of any such google native API that can provide a progress of instance start.

However this is a quick workaround check if this fits your requirement.

You can either use the Google Startup script or the native linux rc.local. The concept is the same, so explaining it for the case of rc.local [as it is generic and not tied to google]

We know that the last process in a bootup sequence that runs is rc.local. Any command or script or call that is in this rc.local [which is a sh or bash script by itself] will be executed at the end of boot process.

So the idea would be in the google image in case of rc.local, have a script or a call which send your a notification or writes a output to central system like KV or cloud storage the state that bootup is all done.

Upvotes: 1

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