google cloud Stackdriver Metrics to scale an Manage instance group - Regional

What are the Stackdriver Metrics we can use to autoscale Regional Manage instance groups ? When i check the docs it says Regional managed instance groups do not support filtering for per-instance metrics. Regional managed instance groups do not support autoscaling using per-group metrics.

Is that mean I can not use any Stackdriver Metrics other than CPU ?

Based on the documentation, you're right by saying that Regional Manage Instance Group have some limitations:

• You cannot autoscale based on Cloud Monitoring logs-based metrics.
• Regional managed instance groups do not support filtering for per-instance metrics.
• Regional managed instance groups do not support autoscaling using per-group metrics.

However, you can still using the autoscaler capability by using the standard form:

• Scaling based on CPU utilization
• Scaling based on load balancing serving capacity