Why is the google app engine not checking my health check interval?

I am using Google App Engine Agile Framework (Node.js)

I have my own healthcheck implementation, but it runs every second, not the 8 seconds I configured below.

Since my health check does some things that are not trivial, I would like to remove some load from my server by increasing the interval

health_check:
  enable_health_check: True
  check_interval_sec: 8
  unhealthy_threshold: 10
  healthy_threshold: 2
  timeout_sec: 8

      

        
        
        
      

    

Any idea why my spacing won't work?