I am trying to create Google Flexible Appengine using terraform script with automatic scaling enabled. Manually using “gcloud app deploy” command, below configuration (app.yaml) works and flexible appengnine gets deployed in google cloud.

min_num_instances: 1 <======
max_num_instances: 15 <======
cool_down_period_sec: 180
target_utilization: 0.85
target_concurrent_requests: 100
max_concurrent_requests: 50

I dont find equivalent configuration to use in terraform script for min_num_instances and max_num_instances.
Instead terraform documentation has min_idle_instances and max_idle_instances. But when i use this for Flexible Appengine, i get the below error,

Error: Error updating FlexibleAppVersion “apps/uday-msb-2/services/versa-rns/versions/v1”: googleapi: Error 400: VM-based automatic scaling should NOT have the following parameter(s): [min_idle_instances]

So, i need to implement min_num_instances and max_num_instances in terraform scripts for Google Flexible App Engine. Please help.

Terraform version used:
terraform --version
Terraform v0.15.3
on linux_amd64 (ubuntu 18.04)