I want to fetch the Uptime percentage from the above image to a third party application I am making. I have gone through various documentation but couldn't find anything!
Can anyone guide me through?
It's not possible for now to generate such metric / graph to show uptime percentage of the VM's.
You may try to extract that information using cloud trace API.
Another approach may be to use MQL query to create a custom metric to show total uptime agregated by hours/days etc.
fetch gce_instance
| metric 'compute.googleapis.com/instance/uptime'
| filter (metric.instance_name == 'instance-1')
| align delta(1d)
| every 1d
| group_by [], [value_uptime_mean: mean(value.uptime)]
Additionally you may find those answers helpful:
How to generate uptime reports through Google Cloud Stackdriver?
How to get uptime total and percentage of GCP compute vm instance through MQL?
Get google cloud uptime history to a third party application