Configmaps and secrets shared between multiple canary deployments get deleted when one canary using them no longer exist

[zeot]

Describe the bug

"primary" config maps and secrets used by multiple canary deployments are when the latest updated canary no longer exists.

The ownerReferences for "primary" configmaps and secrets is set to the canary triggering the creation of it, and is overwritten when the "primary" configmap or secret already exists.

To Reproduce

1. Create a configmap or secrets
2. Create two deployments and canaries using the configmap or secret and wait for them to finish roll-out
3. Delete the last canary you created

Expected behavior

When a "primary" resource of a configmap or secret already exist for a canary, the ownerReferences should be preserved and the new canary should be appended to the list. This will make sure the configmap or secret is never deleted while still in use.

Additional context

• Flagger version: 1.15
• Kubernetes version: 1.20.9
• Service Mesh provider: Istio
• Ingress provider: Istio