I'm running a Docker container in the GAE Flexible Environment beta and have my auto-scaling configured like so:
automatic_scaling:
min_num_instances: 2
max_num_instances: 10
cool_down_period_sec: 60
cpu_utilization:
target_utilization: 0.75
My CPU utilization chart in the console for the corresponding Compute Engine VM instances looks like this:
And yet for the last 30+ minutes GAE has been running the maximum 10 instances. Looking at my application's logs, it doesn't appear to be inordinately busy either. Yet this situation happens regularly.
Why does GAE scale so aggressively? Is there a better place than the CPU utilization chart to find the data it uses to drive scaling decisions?