feat!: Add validation of Autoscaler config against JSON schema

[nielm]

Fully Deprecate minNodes, maxNodes from configuration

Validate the config against a JSON schema.

Add command line config validator for JSON and GKE configMaps

BREAKING CHANGE: previous configs may fail due to stricter configuration validation.

[nielm]

Potential fix for #318

[alexlo03]

Hello, this looks good 1) can you please document what the behavior would be if the configuration is invalid? looks like "no-op plus error log" 2) maybe there should be a metric outcome in addition to the logs outcome

[nielm]

Hello, this looks good

1. can you please document what the behavior would be if the configuration is invalid? looks like "no-op plus error log"
2. maybe there should be a metric outcome in addition to the logs outcome

yes, the poller component will detect the invalid configuration and this will result in a no-op along with:

• An error log message from the poller
• incrementing the poller/requests-failed metric
• sending an error to Cloud Error Reporting in the cloud console.

This will happen every $polling_interval until the config is fixed.