How the FelixConfiguration is being recreated and how to change its default values?

[PawelJablonski-Dynatrace]

Hello Team,

I would like to understand the behavior of recreating FelixConfiguration resource. I have reinstalled calico/tigera to version v3.28.1 on my k8s cluster. By default it created following FelixConfiguration resource:

% kubectl -n calico-system describe FelixConfiguration default
Name:         default
Namespace:    
Labels:       <none>
Annotations:  operator.tigera.io/bpfEnabled: false
              projectcalico.org/metadata:
                {"uid":"32bb45a5-ec0f-4916-babd-6f21fc89972b","generation":1,"creationTimestamp":"2024-08-09T10:09:35Z","managedFields":[{"manager":"opera...
API Version:  crd.projectcalico.org/v1
Kind:         FelixConfiguration
Metadata:
  Creation Timestamp:  2024-08-09T10:09:35Z
  Generation:          4
  Resource Version:    747891792
  UID:                 32bb45a5-ec0f-4916-babd-6f21fc89972b
Spec:
  Bpf Enabled:          false
  Bpf Log Level:        
  Floating I Ps:        Disabled
  Health Port:          9099
  Log Severity Screen:  Info
  Reporting Interval:   0s
  Route Table Range:
    Max:      99
    Min:      65
  Vxlan VNI:  4096
Events:       <none>

This configuration results in following log entry:

[UnknownClass] felix/config_params.go 1043 Proceeding with `RouteTableRange` config option This field has been deprecated in favor of `RouteTableRanges` 

I have modified the spec entry locally and reapplied it via calicoctl to following values:

spec:
  bpfEnabled: false
  bpfLogLevel: ""
  floatingIPs: Disabled
  healthPort: 9099
  logSeverityScreen: Info
  reportingInterval: 0s
  routeTableRanges:
  - max: 99
    min: 65
  vxlanVNI: 4096

This was accepted and after restart of calico-nodes the log was changed to:

felix/config_params.go 1083: Both `RouteTableRanges` and deprecated `RouteTableRange` options are set. `RouteTableRanges` value will be given precedence.

When I have tried to describe the FelixConfiguration once again, I found that both options were present, 'routeTableRanges' and my previous 'routeTableRange' which I tried to remove.

Then I tried to remove the FelixConfiguration manually and it was immediately recreated with its default values which I posted at the top of this post.

What is recommendation for configuring this part to be upgrade-safe when the previous field will be removed? How to get rid of the warning in the log?